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The Pan-STARRS1 Photometric System
The Pan-STARRS1 survey is collecting multi-epoch, multi-colorobservations of the sky north of declination -30° tounprecedented depths. These data are being photometrically andastrometrically calibrated and will serve as a reference for many otherpurposes. In this paper, we present our determination of the Pan-STARRS1photometric system: g P1, r P1, i P1, zP1, y P1, and w P1. The Pan-STARRS1photometric system is fundamentally based on the Hubble Space TelescopeCalspec spectrophotometric observations, which in turn are fundamentallybased on models of white dwarf atmospheres. We define the Pan-STARRS1magnitude system and describe in detail our measurement of the systempassbands, including both the instrumental sensitivity and atmospherictransmission functions. By-products, including transformations to otherphotometric systems, Galactic extinction, and stellar locus, are alsoprovided. We close with a discussion of remaining systematic errors.
| The Spectroscopic Diversity of Type Ia Supernovae
We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia),including 2065 previously unpublished spectra, obtained during 1993-2008through the Center for Astrophysics Supernova Program. There are onaverage eight spectra for each of the 313 SNe Ia with at least twospectra. Most of the spectra were obtained with the FAST spectrograph atthe Fred Lawrence Whipple Observatory 1.5 m telescope and reduced in aconsistent manner, making this data set well suited for studies of SN Iaspectroscopic diversity. Using additional data from the literature, westudy the spectroscopic and photometric properties of SNe Ia as afunction of spectroscopic class using the classification schemes ofBranch et al. and Wang et al. The width-luminosity relation appears tobe steeper for SNe Ia with broader lines, although the result is notstatistically significant with the present sample. Based on theevolution of the characteristic Si II ?6355 line, we proposeimproved methods for measuring velocity gradients, revealing a largerrange than previously suspected, from ~0 to ~400 km s-1day-1 considering the instantaneous velocity declinerate at maximum light. We find a weaker and less significant correlationbetween Si II velocity and intrinsic B - V color at maximum lightthan reported by Foley et al., owing to a more comprehensive treatmentof uncertainties and host galaxy dust. We study the extent of nuclearburning and the presence of unburnt carbon in the outermost layers ofthe ejecta and report new detections of C II ?6580 in 23early-time SN Ia spectra. The frequency of C II detections is not higherin SNe Ia with bluer colors or narrower light curves, in conflict withthe recent results of Thomas et al. Based on nebular spectra of 27 SNeIa, we find no relation between the FWHM of the iron emission feature at~4700 Å and ?m 15(B) after removing the twolow-luminosity SN 1986G and SN 1991bg, suggesting that the peakluminosity is not strongly dependent on the kinetic energy of theexplosion for most SNe Ia. Finally, we confirm the correlation ofvelocity shifts in some nebular lines with the intrinsic B - Vcolor of SNe Ia at maximum light, although several outliers suggest apossible non-monotonic behavior for the largest blueshifts.Based in part on observations obtained at the F. L. Whipple Observatory,which is operated by the Smithsonian Astrophysical Observatory, the MMTObservatory, a joint facility of the Smithsonian Institution and theUniversity of Arizona, and with the 6.5 m Magellan Telescopeslocated at Las Campanas Observatory, Chile.
| A Mismatch in the Ultraviolet Spectra between Low-redshift and Intermediate-redshift Type Ia Supernovae as a Possible Systematic Uncertainty for Supernova Cosmology
We present Keck high-quality rest-frame ultraviolet (UV) through opticalspectra of 21 Type Ia supernovae (SNe Ia) in the redshift range 0.11<= z <= 0.37 and a mean redshift of 0.22 that were discoveredduring the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using thebroadband photometry of the SDSS survey, we are able to reconstruct theSN host-galaxy spectral energy distributions (SEDs), allowing for acorrection for the host-galaxy contamination in the SN Ia spectra.Comparison of composite spectra constructed from a subsample of 17high-quality spectra to those created from a low-redshift sample withotherwise similar properties shows that the Keck/SDSS SNe Ia have, onaverage, extremely similar rest-frame optical spectra but show a UV fluxexcess. This observation is confirmed by comparing synthesized broadbandcolors of the individual spectra, showing a difference in mean colors atthe 2.4?-4.4? level for various UV colors. We further see aslight difference in the UV spectral shape between SNe with low-mass andhigh-mass host galaxies. Additionally, we detect a relationship betweenthe flux ratio at 2770 and 2900 Å and peak luminosity that differsfrom that observed at low redshift. We find that changing the UV SED ofan SN Ia within the observed dispersion can change the inferred distancemoduli by ~0.1 mag. This effect only occurs when the data probe therest-frame UV. We suggest that this discrepancy could be due todifferences in the host-galaxy population of the two SN samples or tosmall-sample statistics.
| uvby-? photometry and kinematics of metal-poor stars: A search for moving groups in the Galactic Stellar Halo
The possible presence of moving groups in the local Galactic stellarhalo has been examined based on new uvby-? photometry for a sampleof 143 metal-poor stars joined to the photometry of 1553 stars from theprevious catalogues of Schuster & Nissen (1988), Schuster et al.(1993), and Schuster et al. (2006). This new set of photometric data,together with radial velocities and proper motions taken from theliterature, have allowed us to obtain Galactic space velocities U', V',and W' for nearly the entire sample. With this kinematic information,three diagrams: the [Fe/H] vs V_rot, the Bottlinger (V' vs U') and theToomre (V' vs (U'^2 + W'^2)^{1/2}) have been obtained and used toidentify probable groups of stars in common between them. Onceidentified, these groups were compared to moving groups reported in theliterature. In particular, probable members of the Kapteyn group and? Cen were identified.
| Age and Structure Parameters of the Remote M31 Globular Cluster B514 Based on HST, 2MASS, GALEX, and BATC Observations
B514 is a remote M31 globular cluster (GC) which is located at aprojected distance of Rp ~= 55 kpc. Deep observations withthe Advanced Camera for Surveys on the Hubble Space Telescope are usedto provide accurate integrated light and star counts of B514. Bycoupling the analysis of the distribution of the integrated light withstar counts, we are able to reliably follow the profile of the clusterout to ~40''. Based on the combined profile, we study in detail itssurface brightness distribution in the F606W and F814W filters anddetermine its structural parameters by fitting a single-mass isotropicKing model. The results showed that the surface brightness distributiondeparts from the best-fit King model for r > 10''. B514 is quite flatin the inner region and has a larger half-light radius than the majorityof normal GCs of the same luminosity. It is interesting that, in theMV versus log Rh plane, B514 lies nearly on thethreshold for ordinary GCs as defined by Mackey & van den Bergh. Inaddition, B514 was observed as part of theBeijing-Arizona-Taiwan-Connecticut (BATC) Multicolor Sky Survey, using13 intermediate-band filters covering a wavelength range of 3000-8500Å. Based on aperture photometry, we obtain its spectral energydistributions (SEDs) as defined by the 13 BATC filters. We determine thecluster's age and mass by comparing its SEDs (from 2267 to 20000Å, comprised of photometric data from the near-ultraviolet band ofthe Galaxy Evolution Explorer, 5 Sloan Digital Sky Survey bands, 13 BATCintermediate-band filters, and Two Micron All Sky Survey near-infraredJHK s filters) with theoretical stellar population synthesismodels, resulting in an age of 11.5 ± 3.5 Gyr. This age confirmsthe previous suggestion that B514 is an old GC in M31. B514 has a massof 0.96-1.08 × 106 M &sun; and is amedium-mass GC in M31.
| Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library
Context. The spectral predictions of stellar population models are notas accurate in the ultra-violet (UV) as in the optical wavelengthdomain. One of the reasons is the lack of high-quality stellarlibraries. The New Generation Stellar Library (NGSL), recently released,represents a significant step towards the improvement of this situation. Aims: To prepare NGSL for population synthesis, we determined theatmospheric parameters of its stars, we assessed the precision of thewavelength calibration and characterised its intrinsic resolution. Wealso measured the Galactic extinction for each of the NGSL stars. Methods: For our analyses we used ULySS, a full spectrum fittingpackage, fitting the NGSL spectra against the MILES interpolator. Results: We find that the wavelength calibration is precise up to 0.1px, after correcting a systematic effect in the optical range. Thespectral resolution varies from 3 Å in the UV to 10 Å in thenear-infrared (NIR), corresponding to a roughly constant reciprocalresolution R = ?/?? ? 1000 and an instrumentalvelocity dispersion ?ins ? 130 km s-1. Wederived the atmospheric parameters homogeneously. The precision for theFGK stars is 42 K, 0.24 and 0.09 dex for Teff, log g and[Fe/H], respectively. The corresponding mean errors are 29 K, 0.50 and0.48 dex for the M stars, and for the OBA stars they are 4.5 percent,0.44 and 0.18 dex. The comparison with the literature shows that ourresults are not biased.Table A1 is only available at CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/538/A143
| The GALEX Arecibo SDSS Survey. V. The Relation between the H I Content of Galaxies and Metal Enrichment at Their Outskirts
We have obtained long-slit spectra of 174 star-forming galaxies withstellar masses greater than 1010 M &sun; fromthe GALEX Arecibo Sloan Digital Sky Survey (GASS) survey. These galaxieshave both H I and H2 mass measurements. The averagemetallicity profile is strikingly flat out to R 90, theradius enclosing 90% of the r-band light. Metallicity profiles whichdecline steadily with radius are found primarily for galaxies in oursample with low stellar mass (log(M *) < 10.2),concentration, and/or mean stellar mass density. Beyond ~R90, however, around 10% of the galaxies in our sample exhibita sharp downturn in metallicity. Remarkably, we find that the magnitudeof the outer metallicity drop is well correlated with the total H Icontent of the galaxy (measured as f H I = M H I/M *). We examine the radial profiles of stellarpopulation ages and star formation rate densities, and conclude that thegalaxies with largest outer metallicity drops are actively growing theirstellar disks, with mass-doubling times across the whole disk onlyone-third as long as a typical GASS galaxy. We also describe acorrelation between local stellar mass density and metallicity, which isvalid across all galaxies in our sample. We argue that much of therecent stellar mass growth at the edges of these galaxies can be linkedto the accretion or radial transport of relatively pristine gas frombeyond the galaxies' stellar disks.
| First Results from Pan-STARRS1: Faint, High Proper Motion White Dwarfs in the Medium-Deep Fields
The Pan-STARRS1 survey has obtained multi-epoch imaging in five bands(Pan-STARRS1 g P1, r P1, i P1, zP1, and y P1) on 12 "Medium-Deep fields," each ofwhich spans a 3fdg3 circle. For the period between 2009 April and 2011April these fields were observed 50-200 times. Using a reduced propermotion diagram, we have extracted a list of 47 white dwarf (WD)candidates whose Pan-STARRS1 astrometry indicates a non-zero propermotion at the 6? level, with a typical 1? proper motionuncertainty of 10 mas yr-1. We also used astrometryfrom the Sloan Digital Sky Survey (when available) and USNO-B to assessour proper motion fits. None of the WD candidates exhibits evidence ofstatistically significant parallaxes, with a typical 1?uncertainty of 8 mas. Twelve of these candidates are known WDs,including the high proper motion (1farcs7 yr-1) WD LHS291. We confirm seven more objects as WDs through optical spectroscopy.Based on the Pan-STARRS1 colors, ten of the stars are likely to be coolWDs with 4170 K
| Beryllium and Alpha-element Abundances in a Large Sample of Metal-poor Stars
The light elements, Li, Be, and B, provide tracers for many aspects ofastronomy including stellar structure, Galactic evolution, andcosmology. We have made observations of Be in 117 metal-poor starsranging in metallicity from [Fe/H] = -0.5 to -3.5 with KeckI/HIRES. Our spectra are high resolution (~42,000) and high signal tonoise (the median is 106 per pixel). We have determined the stellarparameters spectroscopically from lines of Fe I, Fe II, Ti I, and Ti II.The abundances of Be and O were derived by spectrum synthesistechniques, while abundances of Fe, Ti, and Mg were found from manyspectral line measurements. There is a linear relationship between[Fe/H] and A(Be) with a slope of +0.88 ± 0.03 over three ordersof magnitude in [Fe/H]. We find that Be is enhanced relative to Fe;[Be/Fe] is +0.40 near [Fe/H] ~-3.3 and drops to 0.0 near [Fe/H]~-1.7. For the relationship between A(Be) and [O/H], we find agradual change in slope from 0.69 ± 0.13 for the Be-poor/O-poorstars to 1.13 ± 0.10 for the Be-rich/O-rich stars. Inasmuch asthe relationship between [Fe/H] and [O/H] seems robustly linear (slope =+0.75 ± 0.03), we conclude that the slope change in Be versus Ois due to the Be abundance. Much of the Be would have been formed in thevicinity of Type II supernova (SN II) in the early history of the Galaxyand by Galactic cosmic-ray (GCR) spallation in the later eras. AlthoughBe is a by-product of CNO, we have used Ti and Mg abundances asalpha-element surrogates for O in part because O abundances are rathersensitive to both stellar temperature and surface gravity. We find thatA(Be) tracks [Ti/H] very well with a slope of 1.00 ± 0.04. Italso tracks [Mg/H] very well with a slope of 0.88 ± 0.03. We havekinematic information on 114 stars in our sample and they divide equallyinto dissipative and accretive stars. Almost the full range of [Fe/H]and [O/H] is covered in each group. There are distinct differences inthe relationships of A(Be) and [Fe/H] and of A(Be) and [O/H] for thedissipative and the accretive stars. It is likely that the formation ofBe in the accretive stars was primarily in the vicinity of SN II, whilethe Be in the dissipative stars was primarily formed by GCR spallation.We find that Be is not as good a cosmochronometer as Fe. We have found aspread in A(Be) that is valid at the 4? level between [O/H] =-0.5 and -1.0, which corresponds to -0.9 and-1.6 in [Fe/H].
| X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
X-shooter is the first 2nd generation instrument of the ESO Very LargeTelescope (VLT). It is a very efficient, single-target,intermediate-resolution spectrograph that was installed at theCassegrain focus of UT2 in 2009. The instrument covers, in a singleexposure, the spectral range from 300 to 2500 nm. It is designed tomaximize the sensitivity in this spectral range through dichroicsplitting in three arms with optimized optics, coatings, dispersiveelements and detectors. It operates at intermediate spectral resolution(R ~ 4000-17 000, depending on wavelength and slit width) with fixedéchelle spectral format (prism cross-dispersers) in the threearms. It includes a 1.8? × 4? integral field unit asan alternative to the 11'' long slits. A dedicated data reductionpackage delivers fully calibrated two-dimensional and extracted spectraover the full wavelength range. We describe the main characteristics ofthe instrument and present its performance as measured duringcommissioning, science verification and the first months of scienceoperations.
| Photometric selection of Type Ia supernovae in the Supernova Legacy Survey
We present a sample of 485 photometrically identified Type Ia supernovacandidates mined from the first three years of data of the CFHTSuperNova Legacy Survey (SNLS). The images were submitted to a deferredprocessing independent of the SNLS real-time detection pipeline. Lightcurves of all transient events were reconstructed in the gM,rM, iM and zM filters and submitted toautomated sequential cuts in order to identify possible supernovae. Purenoise and long-term variable events were rejected by light curve shapecriteria. Type Ia supernova identification relied on eventcharacteristics fitted to their light curves assuming the events to benormal SNe Ia. The light curve fitter SALT2 was used for this purpose,assigning host galaxy photometric redshifts to the tested events. Theselected sample of 485 candidates is one magnitude deeper than thatallowed by the SNLS spectroscopic identification. The contamination bysupernovae of other types is estimated to be 4%. Testing Hubble diagramresiduals with this enlarged sample allows us to measure the Malmquistbias due to spectroscopic selections directly. The result is fullyconsistent with the precise Monte Carlo based estimate used to correctSN Ia distance moduli in the SNLS 3-year cosmological analyses. Thispaper demonstrates the feasibility of a photometric selection of highredshift supernovae with known host galaxy redshifts, openinginteresting prospects for cosmological analyses from future largephotometric SN Ia surveys.
| Galactic S Stars: Investigations of Color, Motion, and Spectral Features
Known bright S stars, recognized as such by their enhanced s-processabundances and C/O ratio, are typically members of the asymptotic giantbranch (AGB) or the red giant branch. Few modern digital spectra forthese objects have been published, from which intermediate resolutionspectral indices and classifications could be derived. For published Sstars, we find accurate positions using the Two-Micron All Sky Survey(2MASS), and use the FAST spectrograph of the Tillinghast reflector onMt. Hopkins to obtain the spectra of 57 objects. We make available adigital S star spectral atlas consisting of 14 spectra of S stars withdiverse spectral features. We define and derive basic spectral indicesthat can help distinguish S stars from late-type (M) giants and carbonstars. We convolve all our spectra with the Sloan Digital Sky Surveybandpasses, and employ the resulting gri magnitudes together with 2MASSJHKs mags to investigate S star colors. These objects havecolors similar to carbon and M stars, and are therefore difficult todistinguish by color alone. Using near- and mid-infrared colors fromIRAS and Akari, we identify some of the stars as intrinsic (AGB) orextrinsic (with abundances enhanced by past mass transfer). We also useV band and 2MASS magnitudes to calculate a temperature index for starsin the sample. We analyze the proper motions and parallaxes of oursample stars to determine upper and lower limit absolute magnitudes anddistances, and confirm that most are probably giants.
| Nebular and global properties of the gravitationally lensed galaxy "the 8 o'clock arc"
We present the analysis of new near-infrared, intermediate-resolutionspectra of the gravitationally lensed galaxy "the 8 o'clock arc" atzsys = 2.7350 obtained with the X-shooter spectrograph on theVery Large Telescope. These rest-frame optical data, combined withHubble and Spitzer Space Telescopes images, provide very valuableinformation, which nicely complement our previous detailed rest-frame UVspectral analysis, and make the 8 o'clock arc one of the betterunderstood "normal" star-forming galaxies at this early epoch of thehistory of the Universe. From high-resolution HST images, we reconstructthe morphology of the arc in the source plane, and identify that thesource is formed of two majors parts, the main galaxy component and asmaller blob separated by 1.2 kpc in projected distance. The blob, witha twice larger magnification factor, is resolved in the X-shooterspectra. The multi-Gaussian fitting of detected nebular emission linesand the spectral energy distribution modeling of the availablemulti-wavelength photometry provide the census of gaseous and stellardust extinctions, gas-phase metallicities, star-formation rates (SFRs),and stellar, gas, and dynamical masses for both the main galaxy and theblob. As a result, the 8 o'clock arc shows a marginal trend for a moreattenuated ionized gas than stars, and supports a dependence of the dustproperties on the SFR. With a high specific star-formation rate, SSFR =33 ± 19 Gyr-1, this lensed Lyman-break galaxy deviatesfrom the mass-SFR relation, and is characterized by a young age of40+25-20 Myr and a high gas fraction of about 72%.The 8 o'clock arc satisfies the fundamental mass, SFR, and metallicityrelation, and favors that it holds up beyond z ? 2.5. We believethat the blob, with a gas mass Mgas = (2.2 ± 0.9)× 109 M&sun; (one order of magnitude lowerthan the mass of the galaxy), a half-light radius r1/2 = 0.53± 0.05 kpc, a star-formation rate SFRH? = 33± 19 M&sun; yr-1, and in rotation aroundthe main core of the galaxy, is one of these star-forming clumpscommonly observed in z > 1 star-forming galaxies, because it ischaracterized by very similar physical properties. The knowledge ofdetailed physical properties of these clumps is a very useful input tomodels that aim to predict the formation and evolution of these clumpswithin high-redshift objects.Based on X-shooter observations made with the European SouthernObservatory VLT/Kueyen telescope, Paranal, Chile, collected under theprogramme ID No. 284.A-5006(A).Based on observations made with theNASA/ESA Hubble Space Telescope, obtained from the data archive at theSpace Telescope Science Institute.
| Properties of star-forming galaxies in a cluster and its surrounding structure at z=1.46
We conduct a wide-field narrow-band imaging survey of [O II] emitters inand around the XMMXCS J2215.9-1738 cluster at z= 1.46 withSubaru/Suprime-Cam. In a 32 × 23 arcmin2 area, weselect 380 [O II] emitting galaxies down to 1.4 × 10-17erg s-1 cm-2. Among them, 16 [O II] emitters inthe central region of the cluster are confirmed by near-infraredspectroscopy with Subaru/MOIRCS, suggesting that our photometricselection is valid for sample [O II] emitters at z= 1.46. We find that[O II] emitters are distributed along filamentary large-scale structuresaround the cluster, which are among the largest structures ofstar-forming galaxies ever identified at 1.3 ?z? 3.0. Wedefine several environments such as cluster core, outskirts, filamentand field in order to investigate the environment dependence ofstar-forming galaxies at z= 1.46. The colour-magnitude diagram of z'-Kversus K for the [O II] emitting galaxies shows that a significantlyhigher fraction of [O II] emitters with red z'-K colours is seen in thecluster core than in other environments. It seems that the environmentthat hosts such red star-forming galaxies shifts from the core region atz= 1.46 to the outskirts of clusters at lower redshifts. A multicolouranalysis of the red emitters indicates that these galaxies are more likenearly passively evolving galaxies which host [O II] emitting activegalactic nuclei (AGNs), rather than dust-reddened star-forming [O II]emitters. We argue therefore that AGN feedback may be one of thecritical processes to quench star formation in massive galaxies inhigh-density regions. The emission line ratios of [O III]/H? and [NII]/H? of the [O II] emitters in the cluster core support theinference that there is a moderate contribution of AGN to the emitters.We also find that the cluster has experienced high star formationactivities at rates comparable to that in the field at z= 1.46 incontrast to lower redshift clusters, and that star formation activity ingalaxy clusters on average increases with redshift up to z= 1.46. Inaddition, line ratios of [N II]/H? and [O III]/H? indicatethat a mass-metallicity relation exists in the cluster at z= 1.46, whichis similar to that of star-forming galaxies in the field at z˜ 2.These results all suggest that at z˜ 1.5 star formation activityin the cluster core becomes as high as those in low-density environmentsand that there is apparently not yet a strong environmental dependence,except for the red emitters.
| SNLS3: Constraints on Dark Energy Combining the Supernova Legacy Survey Three-year Data with Other Probes
We present observational constraints on the nature of dark energy usingthe Supernova Legacy Survey three-year sample (SNLS3) of Guy et al. andConley et al. We use the 472 Type Ia supernovae (SNe Ia) in this sample,accounting for recently discovered correlations between SN Ia luminosityand host galaxy properties, and include the effects of all identifiedsystematic uncertainties directly in the cosmological fits. Combiningthe SNLS3 data with the full WMAP7 power spectrum, the Sloan Digital SkySurvey luminous red galaxy power spectrum, and a prior on the Hubbleconstant H 0 from SHOES, in a flat universe we find? m = 0.269 ± 0.015 and w =-1.061+0.069 - 0.068 (where the uncertaintiesinclude all statistical and SN Ia systematic errors)—a 6.5%measure of the dark energy equation-of-state parameter w. Thestatistical and systematic uncertainties are approximately equal, withthe systematic uncertainties dominated by the photometric calibration ofthe SN Ia fluxes—without these calibration effects, systematicscontribute only a ~2% error in w. When relaxing the assumption offlatness, we find ? m = 0.271 ± 0.015,? k = -0.002 ± 0.006, and w =-1.069+0.091 - 0.092. Parameterizing the timeevolution of w as w(a) = w 0 + wa (1 - a) gives w0 = -0.905 ± 0.196, wa =-0.984+1.094 - 1.097 in a flat universe. All ofour results are consistent with a flat, w = -1 universe. The size of theSNLS3 sample allows various tests to be performed with the SNesegregated according to their light curve and host galaxy properties. Wefind that the cosmological constraints derived from these differentsubsamples are consistent. There is evidence that the coefficient,?, relating SN Ia luminosity and color, varies with host parametersat >4? significance (in addition to the known SNluminosity-host relation); however, this has only a small effect on thecosmological results and is currently a subdominant systematic.
| Multicolor Photometry of the Galaxies in Abell 1775: Substructures, Luminosity Functions, and Star-Formation Properties
An optical photometric observation in 15 bands was carried out for thenearby galaxy cluster Abell 1775 (A 1775) by theBeijing-Arizona-Taiwan-Connecticut (BATC) multi-color system. Over 5000sources' spectral energy distributions (SEDs) were obtained. Since thiscluster has also been observed by the Sloan Digital Sky Survey (SDSS),the BATC SEDs were combined with the SDSS five-band photometric data.Using the combined SEDs, 146 faint galaxies were selected as new membergalaxies by the photometric redshift technique. Based on the positions,redshifts, and 20-band SEDs of member galaxies, dynamical substructuresand luminosity functions (LFs) of A 1775 were investigated. The previousreported bimodal structure of A 1775 has been confirmed: a poorsubcluster with lower redshift, A 1775 A, is located ˜14'southeast to the main concentration, A 1775 B. After taking into accountthe new supplemented member galaxies, a new subcluster, A 1775 C, wasfound along the aligned direction of A 1775 A and A 1775 B. Thedifferent LF faint ends of the two subclusters indicate that A 1775 B isa more dynamically evolved system, while A 1775 A is still dynamicallyyoung. By using the STARLIGHT spectral synthesis code, thestar-formation histories of the member galaxies were studied. Thedependence of the mean stellar ages upon the Hubble type was confirmed,and the environmental effect on star-formation activities for galaxiesin A 1775 B has been explored.
| The Relation between Dynamics and Star Formation in Barred Galaxies
We analyze optical and near-infrared data of a sample of 11 barredspiral galaxies, in order to establish a connection between starformation and bar/spiral dynamics. We find that 22 regions located inthe bars and 20 regions in the spiral arms beyond the end of the barpresent azimuthal color/age gradients that may be attributed to starformation triggering. Assuming a circular motion dynamic model, wecompare the observed age gradient candidates with stellar populationsynthesis models. A link can then be established with the disk dynamicsthat allows us to obtain parameters like the pattern speed of the bar orspiral as well as the positions of resonance radii. We subsequentlycompare the derived pattern speeds with those expected from theoreticaland observational results in the literature (e.g., bars ending nearcorotation). We find a tendency to overestimate bar pattern speedsderived from color gradients in the bar at small radii, away fromcorotation; this trend can be attributed to non-circular motions of theyoung stars born in the bar region. In spiral regions, we find that ~50%of the color gradient candidates are "inverse," i.e., with the directionof stellar aging contrary to that of rotation. The other half of thegradients found in spiral arms have stellar ages that increase in thesame sense as rotation. Of the nine objects with gradients in both barsand spirals, six (67%) appear to have a bar and a spiral with similar? p , while three (33%) do not.
| A Multicolor Photometric Study of the Galaxy Cluster A2589: Dynamics, Luminosity Function, and Star Formation History
Smooth X-ray morphology and non-detection of a radio source at thecenter of A2589 indicate that it is a typical case of a well-relaxedregular galaxy cluster. In this paper, we present a multicolorphotometry for A2589 (z = 0.0414) with 15 intermediate bands in theBeijing-Arizona-Taiwan-Connecticut (BATC) system which covers an opticalwavelength range from 3000 Å to 10000 Å. The spectral energydistributions (SEDs) for more than 5000 sources are achieved down to V ~20 mag in about a 1 deg2 field. A2589 has also been coveredby the Sloan Digital Sky Survey (SDSS) in photometric mode only. Across-identification of the BATC-detected galaxies with the SDSSphotometric catalog yields 1199 galaxies brighter than i = 19.5 mag,among which 68 member galaxies with known spectroscopic redshifts arefound. After combining the SDSS five-band photometric data and the BATCSEDs, photometric redshift is applied to these galaxies to select faintmember galaxies. The color-magnitude relation is taken as a furtherrestriction of early-type cluster galaxies. As a result, 106 galaxiesare newly selected as member galaxies. Spatial distribution of membergalaxies shows a north-south elongation which agrees with the X-raybrightness profile and the orientation of central cD galaxy, NGC 7647.No substructures are detected on the basis of positions and radialvelocities of cluster galaxies, indicating that A2589 is a well-relaxedsystem. The luminosity function of A2589 exhibits a peak atMR ~ -20 mag and a dip at MR ~ -19 mag. Thelow-density outer regions are the preferred habitat of faint galaxies.With the evolutionary population synthesis model, PEGASE, theenvironmental effect on the star formation properties for 68spectroscopically confirmed member galaxies is studied. The outlierfaint galaxies tend to have longer timescales of star formation, shortermean stellar ages, and lower metallicities in the interstellar medium,which can be interpreted in the context of a hierarchical cosmologicalscenario.
| Age and Mass Constraints for a Young Massive Cluster in M31 Based on Spectral Energy Distribution Fitting
VDB0-B195D is a massive, blue star cluster in M31. It was observed aspart of the Beijing-Arizona-Taiwan-Connecticut (BATC) Multicolor SkySurvey using 15 intermediate-band filters covering a wavelength range of3000-10000 Å. Based on aperture photometry, we obtain its spectralenergy distribution (SED) as defined by the 15 BATC filters. We applypreviously established relations between the BATC intermediate-band andthe Johnson-Cousins UBVRI broadband systems to convert our BATCphotometry to the standard system. A detailed comparison shows that ournewly derived VRI magnitudes are fully consistent with previous results,while our new B magnitude agrees to within 2?. In addition, wedetermine the cluster's age and mass by comparing its SED (from 3000 to20000 Å, comprising photometric data in the 15 BATC intermediatebands, optical broadband BVRI, and Two Micron All Sky Surveynear-infrared JHK s data) with theoretical stellar populationsynthesis models, resulting in age and mass determinations of 60.0± 8.0 Myr and (1.1-1.6) × 105 M sun,respectively. This age and mass confirms previous suggestions thatVDB0-B195D is a young massive cluster in M31.
| Bridging model and observed stellar spectra
Accurate model stellar fluxes are key for the analysis of observationsof individual stars or stellar populations. Model spectra differ fromreal stellar spectra due to limitations of the input physical data andadopted simplifications, but can be empirically calibrated to maximizetheir resemblance to actual stellar spectra. We describe a least-squaresprocedure of general use and test it on the MILES library.
| Color Behavior of BL Lacertae Object OJ 287 during an Optical Outburst
This paper studies the color behavior of the BL Lac object OJ 287 duringan optical outburst. Upon revisiting the data from the OJ 94 monitoringproject, and from an analysis of the data obtained with the 60/90 cmSchmidt Telescope of NAOC, we found a bluer-when-brighter chromatism inthis object. The amplitude of variation tends to decrease withfrequency. These results are consistent with the shock-in-jet model. Weran some simulations and confirmed that both amplitude difference andtime delay between variations at different wavelengths can result in thebluer-when-brighter phenomenon. Our observations confirmed that OJ 287underwent a double-peaked outburst about 12 years after 1996, whichprovides further evidence for the binary black hole model in thisobject.
| Characterization of Sloan Digital Sky Survey Stellar Photometry
We study the photometric properties of stars in the data archive of theSloan Digital Sky Survey (SDSS), the prime aim being to understand thephotometric calibration over the entire data set. It is confirmed thatthe photometric calibration of point sources is accurately on the systemdefined by the SDSS standard stars. We have also confirmed that thephotometric synthesis of the SDSS spectrophotometric data givesbroadband fluxes that agree with the photometry with errors of no morethan 0.04 mag and little systematic tilt with wavelength. This verifiesthat the response functions of the 2.5 m telescope system are wellcharacterized. We locate stars in the SDSS photometric system, so thatstars can roughly be classified into spectral classes from the colorinformation. We show how metallicity and surface gravity affect colors,and that stars contained in the SDSS general catalog, plotted in colorspace, show a distribution that matches well with what is anticipatedfrom the variations of metallicity and surface gravity. The color-colorplots are perfectly consistent among the three samples—stars inthe SDSS general catalog, SDSS standard stars, and spectrophotometricstars of Gunn & Stryker—especially when some considerationsare taken into account of the differences (primarily metallicity) of thesamples. We show that the g - r-inverse temperature relation is tightand can be used as a good estimator of the effective temperature ofstars over a fairly wide range of effective temperatures. We alsoconfirm that the colors of G2V stars in the SDSS photometric systemmatch well with the Sun.
| Supernova Constraints and Systematic Uncertainties from the First Three Years of the Supernova Legacy Survey
We combine high-redshift Type Ia supernovae from the first three yearsof the Supernova Legacy Survey (SNLS) with other supernova (SN) samples,primarily at lower redshifts, to form a high-quality joint sample of 472SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SNdata alone require cosmic acceleration at >99.999% confidence,including systematic effects. For the dark energy equation of stateparameter (assumed constant out to at least z = 1.4) in a flat universe,we find w = -0.91+0.16 -0.20(stat)+0.07-0.14(sys) from SNe only, consistent with a cosmologicalconstant. Our fits include a correction for the recently discoveredrelationship between host-galaxy mass and SN absolute brightness. We payparticular attention to systematic uncertainties, characterizing themusing a systematic covariance matrix that incorporates the redshiftdependence of these effects, as well as the shape-luminosity andcolor-luminosity relationships. Unlike previous work, we include theeffects of systematic terms on the empirical light-curve models. Thetotal systematic uncertainty is dominated by calibration terms. Wedescribe how the systematic uncertainties can be reduced with soon to beavailable improved nearby and intermediate-redshift samples,particularly those calibrated onto USNO/SDSS-like systems.Based on observations obtained with MegaPrime/MegaCam, a joint projectof CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT)which is operated by the National Research Council (NRC) of Canada, theInstitut National des Sciences de l'Univers of the Centre National de laRecherche Scientifique (CNRS) of France, and the University of Hawaii.This work is based in part on data products produced at the CanadianAstronomy Data Centre as part of the Canada-France-Hawaii TelescopeLegacy Survey, a collaborative project of NRC and CNRS.
| Probing the Galactic thick disc vertical properties and interfaces
Aims: This work investigates the properties (metallicity andkinematics) and interfaces of the Galactic thick disc as a function ofheight above the Galactic plane. The main aim is to study the thick discin a place where it is the main component of the sample. Methods:We take advantage of former astrometric work in two fields of severalsquare degrees in which accurate proper motions were measured down toV-magnitudes of 18.5 in two directions, one near the north galactic poleand the other at a galactic latitude of 46° and galactic longitudenear 0°. Spectroscopic observations have been acquired in these twofields for a total of about 400 stars down to magnitude 18.0, atspectral resolutions of 3.5 to 6.25 Å. The spectra have beenanalysed with the code ETOILE, comparing the target stellar spectra witha grid of 1400 reference stellar spectra. This comparison allowed us toderive the parameters effective temperature, gravity, [Fe/H] andabsolute magnitude for each target star. Results: The MetallicityDistribution Function (MDF) of the thin-thick-disc-halo system isderived for several height intervals between 0 and 5 kpc above theGalactic plane. The MDFs show a decrease of the ratio of the thin tothick disc stars between the first and second kilo-parsec. This isconsistent with the classical modelling of the vertical density profileof the disc with 2 populations with different scale heights. A verticalmetallicity gradient, ?[Fe/H]/?z = -0.068 ± 0.009 dexkpc-1, is observed in the thick disc. It is discussed interms of scenarios of formation of the thick disc.Based on observations obtained at the Canada-France-Hawaii Telescope(CFHT) which is operated by the National Research Council of Canada, theInstitut National des Sciences de l'Univers of the Centre National de laRecherche Scientifique of France, and the University of Hawaii and atthe T193cm telescope, Observatoire de Haute-Provence, France.Full TablesA.1-A.3, B.1-B.3 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/525/A90
| Coudé-feed stellar spectral library - atmospheric parameters
Context. Empirical libraries of stellar spectra play an important rolein different fields. For example, they are used as reference for theautomatic determination of atmospheric parameters, or for buildingsynthetic stellar populations to study galaxies. The CFLIB(Coudé-feed library, Indo-US) database is at present one of themost complete libraries, in terms of its coverage of the atmosphericparameters space (T{eff}, log g and [Fe/H]) and wavelengthcoverage 3460-9464 Å at a resolution of 1 Å FWHM. Althoughthe atmospheric parameters of most of the stars were determined fromdetailed analyses of high-resolution spectra, for nearly 300 of the 1273stars of the library at least one of the three parameters is missing.For the others, the measurements, compiled from the literature, areinhomogeneous. Aims: In this paper, we re-determine theatmospheric parameters, directly using the CFLIB spectra, and comparethem to the previous studies. Methods: We use the ULySS programto derive the atmospheric parameters, using the ELODIE library as areference. Results: Based on comparisons with several previousstudies we conclude that our determinations are unbiased. For the 958 F,G, and K type stars the precision on T{eff}, log g, and[Fe/H] is respectively 43 K, 0.13 dex and 0.05 dex. For the 53 M starsthey are 82 K, 0.22 dex and 0.28 dex. And for the 260 OBA type stars therelative precision on T{eff} is 5.1%, and on log g, and[Fe/H] the precision is respectively 0.19 dex and 0.16 dex. Theseparameters will be used to re-calibrate the CFLIB fluxes and to producesynthetic spectra of stellar populations.Tables 2 and 3 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/525/A71
| The Ubiquity of the Rapid Neutron-capture Process
To better characterize the abundance patterns produced by the r-process,we have derived new abundances or upper limits for the heavy elementszinc (Zn, Z= 30), yttrium (Y, Z= 39), lanthanum (La, Z= 57), europium(Eu, Z= 63), and lead (Pb, Z= 82). Our sample of 161 metal-poor starsincludes new measurements from 88 high-resolution and highsignal-to-noise spectra obtained with the Tull Spectrograph on the 2.7 mSmith Telescope at the McDonald Observatory, and other abundances areadopted from the literature. We use models of the s-process inasymptotic giant branch stars to characterize the high Pb/Eu ratiosproduced in the s-process at low metallicity, and our new observationsthen allow us to identify a sample of stars with no detectable s-processmaterial. In these stars, we find no significant increase in the Pb/Euratios with increasing metallicity. This suggests that s-processmaterial was not widely dispersed until the overall Galactic metallicitygrew considerably, perhaps even as high as [Fe/H] =-1.4, in contrastwith earlier studies that suggested a much lower mean metallicity. Weidentify a dispersion of at least 0.5 dex in [La/Eu] in metal-poor starswith [Eu/Fe] <+0.6 attributable to the r-process, suggesting thatthere is no unique "pure" r-process elemental ratio among pairs of rareearth elements. We confirm earlier detections of an anti-correlationbetween Y/Eu and Eu/Fe bookended by stars strongly enriched in ther-process (e.g., CS 22892-052) and those with deficiencies of the heavyelements (e.g., HD 122563). We can reproduce the range of Y/Eu ratiosusing simulations of high-entropy neutrino winds of core-collapsesupernovae that include charged-particle and neutron-capture componentsof r-process nucleosynthesis. The heavy element abundance patterns inmost metal-poor stars do not resemble that of CS 22892-052, but thepresence of heavy elements such as Ba in nearly all metal-poor starswithout s-process enrichment suggests that the r-process is a commonphenomenon.This paper includes data taken at The McDonald Observatory of TheUniversity of Texas at Austin.
| Galaxy counterparts of metal-rich damped Ly? absorbers - I. The case of the z = 2.35 DLA towards Q2222-0946
We have initiated a survey using the newly commissioned X-shooterspectrograph to target candidate relatively metal-rich damped Ly?absorbers (DLAs). Our rationale is that high-metallicity DLAs due to theluminosity-metallicity relation likely will have the most luminousgalaxy counterparts. In addition, the spectral coverage of X-shooterallows us to search for not only Ly? emission, but also rest-frameoptical emission lines. We have chosen DLAs where the strongestrest-frame optical lines ([OII], [OIII], H? and H?) fall inthe near-infrared atmospheric transmission bands. In this first paperresulting from the survey, we report on the discovery of the galaxycounterpart of the zabs = 2.354 DLA towards the z = 2.926quasar Q2222-0946. This DLA is amongst the most metal-rich z > 2 DLAsstudied so far at comparable redshifts and there is evidence forsubstantial depletion of refractory elements on to dust grains. Wemeasure metallicities from ZnII, SiII, NiII, MnII and FeII of -0.46 +/-0.07, - 0.51 +/- 0.06, - 0.85 +/- 0.06, - 1.23 +/- 0.06 and -0.99 +/-0.06, respectively. The galaxy is detected in the Ly?, [OIII]??4959, 5007 and H? emission lines at an impactparameter of about 0.8 arcsec (6 kpc at zabs = 2.354). Basedon the H? line, we infer a star formation rate of10Msolaryr-1, which is a lower limit due to thepossibility of slit loss. Compared to the recently determined H?luminosity function for z = 2.2 galaxies, the DLA-galaxy counterpart hasa luminosity of L ~ 0.1L*H?. The emission-line ratiosare 4.0 (Ly?/H?) and 1.2 ([OIII]/H?). In particular,the Ly? line shows clear evidence for resonant scattering effects,namely an asymmetric, redshifted (relative to the systemic redshift)component and a much weaker blueshifted component. The fact that theblueshifted component is relatively weak indicates the presence of agalactic wind.The properties of the galaxy counterpart of this DLA are consistent withthe prediction that metal-rich DLAs are associated with the mostluminous of the DLA-galaxy counterparts.Based on observations carried out at the European Organization forAstronomical Research in the Southern Hemisphere, Chile, under ESOprogramme 084.A-0303(A).E-mail: jfynbo@dark-cosmology.dk
| The Supernova Legacy Survey 3-year sample: Type Ia supernovae photometric distances and cosmological constraints
Aims: We present photometric properties and distance measurementsof 252 high redshift Type Ia supernovae (0.15 < z < 1.1)discovered during the first three years of the Supernova Legacy Survey(SNLS). These events were detected and their multi-colour light curvesmeasured using the MegaPrime/MegaCam instrument at theCanada-France-Hawaii Telescope (CFHT), by repeatedly imaging fourone-square degree fields in four bands. Follow-up spectroscopy wasperformed at the VLT, Gemini and Keck telescopes to confirm the natureof the supernovae and to measure their redshifts. Methods:Systematic uncertainties arising from light curve modeling are studied,making use of two techniques to derive the peak magnitude, shape andcolour of the supernovae, and taking advantage of a precise calibrationof the SNLS fields. Results: A flat ?CDM cosmological fitto 231 SNLS high redshift type Ia supernovae alone gives ?_M =0.211 ± 0.034(stat) ± 0.069(sys). The dominant systematicuncertainty comes from uncertainties in the photometric calibration.Systematic uncertainties from light curve fitters come next with a totalcontribution of ±0.026 on ?_M. No clear evidence is foundfor a possible evolution of the slope (?) of the colour-luminosityrelation with redshift.Based on observations obtained with MegaPrime/MegaCam, a joint projectof CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT)which is operated by the National Research Council (NRC) of Canada, theInstitut National des Sciences de l'Univers of the Centre National de laRecherche Scientifique (CNRS) of France, and the University of Hawaii.This work is based in part on data products produced at the CanadianAstronomy Data Centre as part of the Canada-France-Hawaii TelescopeLegacy Survey, a collaborative project of NRC and CNRS. Based onobservations obtained at the European Southern Observatory using theVery Large Telescope on the Cerro Paranal (ESO Large Programme171.A-0486 & 176.A-0589). Based on observations (programsGS-2003B-Q-8, GN-2003B-Q-9, GS-2004A-Q-11, GN-2004A-Q-19, GS-2004B-Q-31,GN-2004B-Q-16, GS-2005A-Q-11, GN-2005A-Q-11, GS-2005B-Q-6, GN-2005B-Q-7,GN-2006A-Q-7, GN-2006B-Q-10) obtained at the Gemini Observatory, whichis operated by the Association of Universities for Research inAstronomy, Inc., under a cooperative agreement with the NSF on behalf ofthe Gemini partnership: the National Science Foundation (United States),the Particle Physics and Astronomy Research Council (United Kingdom),the National Research Council (Canada), CONICYT (Chile), the AustralianResearch Council (Australia), CNPq (Brazil) and CONICET (Argentina).Based on observations obtained at the W.M. Keck Observatory, which isoperated as a scientific partnership among the California Institute ofTechnology, the University of California and the National Aeronauticsand Space Administration. The Observatory was made possible by thegenerous financial support of the W.M. Keck Foundation. Mark Sullivanacknowledges support from the Royal Society.Table 9 is available inelectronic form at http://aanda.org andat the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/523/A7.Tables 10 and 11 are only available in electronic form at the CDS
| UGC8802: A Massive Disk Galaxy in Formation
We report new observations of the galaxy UGC8802 obtained through theGALEX Arecibo SDSS Survey (GASS), which show this galaxy to be in aremarkable evolutionary state. UGC8802 (GASS35981) is a disk galaxy withstellar mass M * = 2 × 1010 Msun, which appears to contain an additional 2.1 ×1010 M sun of H I gas. New millimeter observationswith the IRAM 30 m telescope indicate a molecular gas mass only a tenththis large. Using deep long-slit spectroscopy, we examine the spatiallyresolved star formation rate (SFR) and metallicity profiles of GASS35981for clues to its history. We find that the star formation surfacedensity in this galaxy is low (?SFR = 0.003 Msun yr-1 kpc-2) and that the starformation is spread remarkably evenly across the galaxy. The lowmolecular gas masses measured in our three IRAM pointings are largelyconsistent with the total star formation measured within the sameapertures. Our MMT long-slit spectrum reveals a sharp drop inmetallicity in the outer disk of GASS35981. The ratio of current SFR toexisting stellar mass surface density in the outer disk is extremelyhigh, implying that all the stars must have formed within the past ~1Gyr. At current SFRs, however, GASS35981 will not consume its H Ireservoir for another 5-7 Gyr. Despite its exceptionally large gasfraction for a galaxy this massive, GASS35981 has a regular rotationcurve and exhibits no sign of a recent interaction or merger. Wespeculate that GASS35981 may have acquired its gas directly from theintergalactic medium, and that GASS35981 and other similar galaxiesidentified in the GASS survey may provide rare local glimpses of gasaccretion processes that were more common during the prime epoch of diskgalaxy formation at z ~ 1.
| Spectra and Hubble Space Telescope Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
We report on work to increase the number of well-measured Type Iasupernovae (SNe Ia) at high redshifts. Light curves, including highsignal-to-noise Hubble Space Telescope data, and spectra of six SNe Iathat were discovered during 2001, are presented. Additionally, for thetwo SNe with z > 1, we present ground-based J-band photometry fromGemini and the Very Large Telescope. These are among the most distantSNe Ia for which ground-based near-IR observations have been obtained.We add these six SNe Ia together with other data sets that have recentlybecome available in the literature to the Union compilation. We havemade a number of refinements to the Union analysis chain, the mostimportant ones being the refitting of all light curves with the SALT2fitter and an improved handling of systematic errors. We call this newcompilation, consisting of 557 SNe, the Union2 compilation. The flatconcordance ?CDM model remains an excellent fit to the Union2data with the best-fit constant equation-of-state parameter w =-0.997+0.050 -0.054(stat)+0.077-0.082(stat + sys together) for a flat universe, or w =-1.038+0.056 -0.059(stat)+0.093-0.097(stat + sys together) with curvature. We also presentimproved constraints on w(z). While no significant change in w withredshift is detected, there is still considerable room for evolution inw. The strength of the constraints depends strongly on redshift. Inparticular, at z >~ 1, the existence and nature of dark energy areonly weakly constrained by the data.Based in part on observations made with the NASA/ESA Hubble SpaceTelescope, obtained from the data archive at the Space Telescope ScienceInstitute (STScI). STScI is operated by the Association of Universitiesfor Research in Astronomy (AURA), Inc. under the NASA contract NAS5-26555. The observations are associated with programs HST-GO-08585 andHST-GO-09075. Based, in part, on observations obtained at the ESO LaSilla Paranal Observatory (ESO programs 67.A-0361 and 169.A-0382).Based, in part, on observations obtained at the Cerro-TololoInter-American Observatory (CTIO), National Optical AstronomyObservatory (NOAO). Based on observations obtained at theCanada-France-Hawaii Telescope (CFHT). Based, in part, on observationsobtained at the Gemini Observatory (Gemini programs GN-2001A-SV-19 andGN-2002A-Q-31). Based, in part on observations obtained at the SubaruTelescope. Based, in part, on data that were obtained at the W. M. KeckObservatory.
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Observation and Astrometry data
| Constellation: | Pégase |
| Right ascension: | 22h11m31.37s |
| Declination: | +18°05'34.1" |
| Apparent magnitude: | 9.463 |
| Proper motion RA: | 507.2 |
| Proper motion Dec: | 57.6 |
| B-T magnitude: | 9.969 |
| V-T magnitude: | 9.505 |
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