Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age
Aims: We present a compilation of spectroscopic data from asurvey of 144 chromospherically active young stars in the solarneighborhood, which may be used to investigate different aspects of itsformation and evolution in terms of kinematics and stellar formationhistory. The data have already been used by us in several studies. Withthis paper, we make all these data accessible to the scientificcommunity for future studies on different topics. Methods: Weperformed spectroscopic observations with echelle spectrographs to coverthe entirety of the optical spectral range simultaneously. Standard datareduction was performed with the IRAF echelle package. We applied thespectral subtraction technique to reveal chromospheric emission in thestars of the sample. The equivalent width of chromospheric emissionlines was measured in the subtracted spectra and then converted tofluxes using equivalent width-flux relationships. Radial and rotationalvelocities were determined by the cross-correlation technique.Kinematics, equivalent widths of the lithium line ?6707.8 Åand spectral types were also determined. Results: A catalog ofspectroscopic data is compiled: radial and rotational velocities, spacemotion, equivalent widths of optical chromospheric activity indicatorsfrom Ca II H & K to the calcium infrared triplet and the lithiumline in ?6708 Å. Fluxes in the chromospheric emission linesand R'_HK are also determined for each observation of a star in thesample. We used these data to investigate the emission levels of ourstars. The study of the H? emission line revealed two differentpopulations of chromospheric emitters in the sample, clearly separatedin the logFH?/Fbol - (V-J) diagram. Thedichotomy may be associated with the age of the stars.Based on observations made with the 2.2 m telescope of theGerman-Spanish Astronomical Centre, Calar Alto (Almería, Spain),operated jointly by the Max-Planck-Institute for Astronomy, Heidelberg,and the Spanish National Commission for Astronomy; the Nordic OpticalTelescope (NOT), operated on the island of La Palma jointly by Denmark,Finland, Iceland, Norway and Sweden, in the Spanish Observatorio delRoque de Los Muchachos of the Instituto de Astrofísica deCanarias; the Isaac Newton Telescope (INT) operated on the island of LaPalma by the Isaac Newton Group in the Spanish Observatorio del Roque deLos Muchachos of the Instituto de Astrofísica de Canarias; withthe Italian Telescopio Nazionale Galileo (TNG) operated on the island ofLa Palma by the Centro Galileo Galilei of the INAF (Istituto Nazionaledi Astrofisica) at the Spanish Observatorio del Roque de Los Muchachosof the Instituto de Astrofísica de Canarias; and with theHobby-Eberly Telescope (HET) operated by McDonald Observatory on behalfof The University of Texas at Austin, the Pennsylvania State University,Stanford University, Ludwig-Maximilians-Universität München,and Georg-August-Universität Göttingen. This research has madeuse of the SIMBAD database and VizieR catalog access tool, operated atCDS, Strasbourg, France.Tables A.1-A.4 and reduced spectra are alsoavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A97
| Spectroscopic study of the Herbig Be star HD 100546
We present new results of a spectroscopic investigation performed forthe ~10 Myr old Herbig Be star HD 100546. The data were collected duringthe period from 1992 to 1995 and consist of 80 high resolution spectrafor H? , H? , He I 5876 Angstroms, and Na I D lines. The lineprofiles show rather significant variability on time scales from lessthan a day to months. The analysis of these data gave arguments infavour of a circumstellar disk in an active mass exchange with HD100546. In addition, the data also show that accretion and stellar windmay be two independent sources of activities on HD 100546, and thecoexistence of them can result in the formation of an additionalenvelope at the sides of the equatorial disk. Two episodes of fastdiscrete accretion were noted during the observed period. In the firstone, a red-shifted absorption was developed for the Balmer lines duringtwo nights in 1992 June. A detailed analysis of this event allowed us topropose a geometrical model for the circumstellar disk responsible forthe observed phenomenon. The second event was observed when the objectwas in state of photometric minimum in 1994 March. During this season, anumber of variable features positionally moving toward higher velocitiescould be identified on the H? profiles. A study of the kinematicalcharacteristics of this moving features leads to the conclusion that astar-grazing comet-like body may be the source of this fast discreteaccretion. In addition, an analysis of the distribution of theinterstellar medium toward the region of the sky containing HD 100546gives strong evidence for the physical association between this star andthe dark cloud DC296.2-7.9. Based on observations collected at theAstrophysical National Laboratory (LNA - Brazil) and the EuropeanSouthern Observatory (ESO)
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
| Csillagkép: | Légy |
| Rektaszcenzió: | 11h46m39.68s |
| Deklináció: | -70°07'25.5" |
| Vizuális fényesség: | 9.014 |
| RA sajátmozgás: | -6.4 |
| Dec sajátmozgás: | 10.2 |
| B-T magnitude: | 9.763 |
| V-T magnitude: | 9.076 |
Katalógusok és elnevezések:
|
