Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
New GCVS Versions for Three Southern Constellations
We are currently working on a version of the General Catalogue ofVariable Stars (GCVS) revised taking into account the new dataaccumulated since the 4th GCVS edition. A draft new version will bereleased for each constellation as soon as the work for theconstellation is finished. It will contain all stars of the 4th GCVSedition plus a complete catalogue of the stars added to the GCVS in theName Lists of Variable Stars Nos. 67 - 78. Now we are ready for thefirst release, containing more than 1300 variable stars in theconstellations of Antlia, Ara, and Telescopium. When preparing therelease, we actively used modern data-mining possibilities to improvevariability types and light elements. This paper introduces the firstrelease of the new GCVS version and presents new results (types, lightelements), based mainly on data mining, for 213 stars.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Radio star catalogue observed in San Juan (RSSJ95)
Using the data observed in San Juan with the photoelectric AstrolabeMark II of the Beijing Astronomical Observatory from February, 1992 toMarch, 1997, the radio star catalogue in San Juan(RSSJ95) has beencompiled. There are 69 radio stars in this catalogue. The positions ofthe radio stars are for the epoch of observation and the equinox J2000.0and a system close to that of the system FK5. The mean precisions are+/-2.2 ms and +/-0.035'' in right ascensions and declinations,respectively. The magnitudes of stars are from 0.9 to 10.7. Thedeclinations are from -2fdg 5 to -60(deg) . The mean epoch is 1995.1.Finally, the comparison results between the Hipparcos catalogue andRSSJ95 are given.
| San Juan radio star catalogue and comparison with HIPPARCOS catalogue.
Not Available
| Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| The chromospheres of late-type stars. II - an atlas of chromospheric lines for selected early-K stars
High-resolution spectra of the chromospheric Na I D lines, Ca I 4227, MgI 4571, 5167, and 5172, the Ca II H and K resonance and IR 8542.144 and8662.170 lines, and H-alpha and H-beta, all observed simultaneously atthe AAT, are presented. These data are presented as the observationalbasis for the self-consistent, semiempirical modeling of the outerphotospheres and chromospheres of the target stars. Stellar activity isfound in the low-chromosphere lines as core-filling and, in some stars,as line-broadening. Integrated fluxes are derived from the differencespectra, formed by subtracting quiet from active spectra, in the Ca II Hand K resonance and IR 8542 and 8662 lines and in H-alpha, which arepresented as chromospheric activity indicators. All the activity indicesexhibit strong correlations, with the exception of the equivalent widthsof H-alpha and H-beta, which are found to be relatively poor activitydiscriminators.
| Optical positions of radiostars. III
Precise optical positions, relative to either the Perth 70 or the AGK3Rcatalog have been obtained for 44 radiostars proposed to the Hipparcosobserving list. Precision levels between 0.17 and 0.28 arcsec wereobtained.
| An astrometric catalogue of radio stars
The first part is presented of a radio star catalog encompassing 186objects whose selection was guided by the priority criteria of theHipparchos Input Catalogue Consortium. Since these criteria are wellsuited to the need for linkage of ground-based optical systems to radioreference frames, this first selection is also considered a suitablebase for the catalog. Seventeen categories of stellar parameters arefurnished for each of the stars, including optical and radio positions,optical and radio parallax, radial velocity, type of variability, andoptical structure.
| The 69th Name-List of Variable Stars
Not Available
| Stellar radio luminosity and stellar rotation
Two measurements of the microwave surface brightness of 63 activechromospheric stars, one related to surface flux and one related to fluxratio, are correlated with rotational parameters. Although both methodsare found to provide similar results, the surface flux method accountsfor more of the variance in the regression. The consistency of theobserved surface brightnesses of the sun and three BY-Dra-type flarestars with the present rotational relationships is considered.
| Microwave spectra and polarization of active stars
Almost-simultaneous observations of 24 active-chromosphere stars withthe VLA and the Parkes 64-m telescope at 4.9, 8.4 and 15 GHz over a 24-hinterval on September 14, 1985 are reported. In all, 14 stars weredetected. There is a striking difference in the power outputs andbrightness temperatures of the higher-optical-luminosity stars (RS CVn,Algol-like and CAII emitters) and the low-luminosity dMe stars; this canbe explained by differences in the surface areas and rotation velocitiesof the two groups of stars. Two three-point spectra show a broad peak inthe region near 8.4 GHz, indicating a transition from optically thick tooptically thin radio sources. For another three stars, two-pointspectral indices are negative, indicating that their spectra peakprobably well below 15 GHz; two stars with two-point positive spectralindices have higher-frequency turnovers, although perhaps below 15 GHz.
| A relation between radio luminosity and rotation for late-type stars
A relation is found between peak radio luminosities measured at 8 GHzand the rotational velocity of 51 late-type F, G, and K stars (includingthe sun). The sample includes both single stars and active components ofclose binary systems, with equatorial surface velocities ranging from 1to 100 km/s. A gyrosynchrotron source model originally developed toexplain solar microwave bursts could explain the relation. The mainparameter depending on rotation rate is the filling factor, i.e., thefraction of the stellar surface and corona occupied by intense magneticfields. As the rotation speed increases, the scale size of the coronalstructures emitting microwave gyrosynchrotron radiation increases, andthere is a corresponding increase in the area of the surface covered byintense starspot magnetic fields. However, the peak magnetic field ofthe starspots probably does not increase significantly above observedsunspot values.
| A microwave survey of southern active stars
The results of a survey of 153 active-chromosphere stars made with theParkes 64-m telescope at 5.0/8.4 GHz from 1981 to 1987 are reported.Microwave emission was detected from 70 stars on at least one occasion,with the highest detection rate of 68 percent from the RS CVn group. TheCa II stars and Algol-type binaries yielded detection rates of 44 and 30percent, respectively. The maximum powers emitted by the stars at5.0/8.4 GHz ranged over five orders of magnitude, with a median of 2.5 x10 to the 10th W/Hz. The maximum brightness temperatures had a smallerrange of three orders of magnitude, with a median of 3.6 x 10 to the 9thK.
| UBV(RI)c photometry for CaII emission stars. I - Observations at Sutherland
Extensive photometry in the UBV(RI)c system is given for 55 stars withstrong Ca II H and K emission. The UBV observations were made relativeto the standard stars of Lloyd Evans et al. (1983) while the (RI)cobservations were made relative to E-region standards over greaterangular distances. The data are plotted in phase diagrams.
| Radial velocities of calcium emission stars. I - Observations at Sutherland
Radial velocities are presented for 53 bright late-type stars withemission in the H and K lines of Ca II, which is indicative of a highlevel of chromospheric activity. Most of the stars are spectroscopicbinaries, for which orbital elements are presented.
| Results of a Southern Radio Survey of Active Chromosphere Stars
Not Available
| An H-alpha survey of southern hemisphere active chromosphere stars
Because of the variety of extraordinary phenomena exhibited by activechromosphere objects, discovery of new, bright surface-active stars isof considerable importance. Ca II emission is a well-known signature ofchromospheric activity, serving even as one of the points of definitionof the class of RS CVn binary stars. In connection with the presentinvestigation, spectroscopic observations of 27 Ca II emission starshave been conducted. The observations make it possible to identifyunambiguously the most chromospherically active stars in the sample. Byobserving the H-alpha line, rather than H and K, it is possible todistinguish nine of these stars which are likely to be observationaltargets as interesting as the extremely surface active objects V711 Tauor FK Com. Of the 27 stars surveyed, two (HD 86005, HD 204128) showedH-alpha as an emission feature above continuum, with estimatedequivalent width 1-2 A.
| Local photometric standards for CaII emission stars
UBV data are given for 108 stars which are suitable local standards for52 stars with strong Ca2 emissions. An additional eight stars wererejected as possible standards because of suspected variability.
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
| Csillagkép: | Légszivattyú |
| Rektaszcenzió: | 10h53m14.87s |
| Deklináció: | -32°59'18.9" |
| Vizuális fényesség: | 8.408 |
| Távolság: | 763.359 parszek |
| RA sajátmozgás: | -23.2 |
| Dec sajátmozgás: | 12.4 |
| B-T magnitude: | 9.954 |
| V-T magnitude: | 8.536 |
Katalógusok és elnevezések:
|
