目录
图像
上传图像
DSS Images Other Images
相关文章
Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
| Spectroscopic and photometric investigations of MAIA candidate stars
Including our own observational material and the Hipparcos photometrydata, we investigate the radial velocity and brightness of suspectedMaia variable stars which are classified also in some examples aspeculiar stars, mainly for the existence of periodic variations withtime-scales of hours. The results lead to the following conclusions: (1)Short-term radial velocity variations have been unambiguously proved forthe A0 V star gamma CrB and the A2 III star gamma UMi. The stars pulsatein an irregular manner. Moreover, gamma CrB shows a multiperiodstructure quite similar to some of the best-studied neighbouring deltaScu stars. (2) In the Hipparcos photometry as well as in our photometricruns we find significant short- and long-term variations in the stars HD8441, 2 Lyn, theta Vir, gamma UMi, and gamma CrB. For ET And theHipparcos data confirm a short-period variation found already earlier.Furthermore, we find changes of the colour index in theta Vir and gammaCrB on a time-scale of days. (3) No proofs for the existence of aseparate class of variables, designated as Maia variables, are found. Ifthe irregular behaviour of our two best-investigated stars gamma CrB andgamma UMi is typical for pulsations in this region of theHertzsprung-Russell diagram, our observational runs are too short andthe accuracy of the measurements too low to exclude such pulsations inthe other stars, however. (4) The radial velocities of the binariesalpha Dra and ET And have been further used for a recalculation of theorbital elements. For HD 8441 and 2 Lyn we estimated the orbitalelements for the first time. (5) Zeeman observations of the stars gammaGem, theta Vir, alpha Dra, 4 Lac, and ET And give no evidence of thepresence of longitudinal magnetic field strengths larger than about 150gauss. Based on spectroscopic observations taken with the 2\,m telescopeat the Th{ü
|
提交文章
相关链接
提交链接
下列团体成员
|
观测天体数据
目录:
|
