Contents
Images
Upload your image
DSS Images Other Images
Related articles
Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
The Hipparcos satellite made measurements of over 9734 known doublestars, 3406 new double stars, and 11,687 unresolved but possible doublestars. The high angular resolution afforded by speckle interferometrymakes it an efficient means to confirm these systems from the ground,which were first discovered from space. Because of its coverage of adifferent region of angular separation-magnitude difference(ρ-Δm) space, speckle interferometry also holds promise toascertain the duplicity of the unresolved Hipparcos ``problem'' stars.Presented are observations of 116 new Hipparcos double stars and 469Hipparcos ``problem stars,'' as well as 238 measures of other doublestars and 246 other high-quality nondetections. Included in these areobservations of double stars listed in the Tycho-2 Catalogue andpossible grid stars for the Space Interferometry Mission.
| The Vienna-KPNO search for Doppler-imaging candidate stars. I. A catalog of stellar-activity indicators for 1058 late-type Hipparcos stars
We present the results from a spectroscopic Ca ii H&K survey of 1058late-type stars selected from a color-limited subsample of the Hipparcoscatalog. Out of these 1058 stars, 371 stars were found to showsignificant H&K emission, most of them previously unknown; 23% withstrong emission, 36% with moderate emission, and 41% with weak emission.These spectra are used to determine absolute H&K emission-linefluxes, radial velocities, and equivalent widths of theluminosity-sensitive Sr ii line at 4077 Ä. Red-wavelengthspectroscopic and Strömgren y photometric follow-up observations ofthe 371 stars with H&K emission are used to additionally determinethe absolute Hα -core flux, the lithium abundance from the Li i6708 Å equivalent width, the rotational velocity vsin i, theradial velocity, and the light variations and its periodicity. Thelatter is interpreted as the stellar rotation period due to aninhomogeneous surface brightness distribution. 156 stars were found withphotometric periods between 0.29 and 64 days, 11 additional systemsshowed quasi-periodic variations possibly in excess of ~50 days. Further54 stars had variations but no unique period was found, and four starswere essentially constant. Altogether, 170 new variable stars werediscovered. Additionally, we found 17 new SB1 (plus 16 new candidates)and 19 new SB2 systems, as well as one definite and two possible new SB3systems. Finally, we present a list of 21 stars that we think are mostsuitable candidates for a detailed study with the Doppler-imagingtechnique. Tables A1--A3 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Rapid follow-up ROSAT observation of GRB 940301.
The strong γ-ray burst of March 1, 1994 was imaged by COMPTEL andfound to have an identical location within the errors as a burst whichoccurred on July 4, 1993. This location coincidence had promptedspeculations on a possible single source origin for both bursts. We haveperformed a ROSAT PSPC mosaic observation within four weeks of GRB940301. The results of these observations and the comparison of theintensities of the detected sources with those detected during the ROSATall-sky-survey in September 1990 are presented. We neither find aflaring X-ray source in the April 1994 observation nor any variabilityof the X-ray sources detected in the all-sky-survey. We discuss theconsequences of our negative result on both, the possibility of thelocation coincidence being due to a repeating burst source as well asdue to two independent sources. In the former case the source couldeither be a Soft Gamma Repeater similar to SGR 1806-20 and SGR 0525-66,or a sofar unknown classical burst repeater. We conclude that aquiescent luminous X-ray source as is found for the above mentioned SoftGamma Repeaters is very unlikely to be present in the case of GRB 930704/ GRB 940301.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Girafe |
| Right ascension: | 06h58m39.30s |
| Declination: | +64°35'33.0" |
| Apparent magnitude: | 7.995 |
| Distance: | 285.714 parsecs |
| Proper motion RA: | 7.8 |
| Proper motion Dec: | -11.1 |
| B-T magnitude: | 9.12 |
| V-T magnitude: | 8.088 |
Catalogs and designations:
|
