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Pre-main sequence star Proper Motion Catalogue
We measured the proper motions of 1250 pre-main sequence (PMS) stars andof 104 PMS candidates spread over all-sky major star-forming regions.This work is the continuation of a previous effort where we obtainedproper motions for 213 PMS stars located in the major southernstar-forming regions. These stars are now included in this present workwith refined astrometry. The major upgrade presented here is theextension of proper motion measurements to other northern and southernstar-forming regions including the well-studied Orion and Taurus-Aurigaregions for objects as faint as V≤16.5. We improve the precision ofthe proper motions which benefited from the inclusion of newobservational material. In the PMS proper motion catalogue presentedhere, we provide for each star the mean position and proper motion aswell as important photometric information when available. We providealso the most common identifier. The rms of proper motions vary from 2to 5 mas/yr depending on the available sources of ancient positions anddepending also on the embedding and binarity of the source. With thiswork, we present the first all-sky catalogue of proper motions of PMSstars.
| Spectroscopic Binaries in a Sample of ROSAT X-Ray Sources South of the Taurus Molecular Clouds
We report the results of our radial velocity monitoring of spectroscopicbinary systems in a sample of X-ray sources from the ROSAT All SkySurvey south of the Taurus-Auriga star-forming region. The originalsample of ~120 sources by Neuhäuser et al. was selected on thebasis of their X-ray properties and the visual magnitude of the nearestoptical counterpart, in such a way as to promote the inclusion of youngobjects. Roughly 20% of those sources have previously been confirmed tobe very young. We focus here on the subset of the original sample thatshows variable radial velocities (43 objects), a few of which have alsobeen flagged previously as being young. New spectroscopic orbits arepresented for 42 of those systems. Two of the binaries, RX J0528.9+1046and RX J0529.3+1210, are indeed weak-lined T Tauri stars likely to beassociated with the λ Ori region. Most of the other binaries areactive objects of the RS Canum Venaticorum type, including several WUrsae Majoris and Algol systems. We detect a strong excess ofshort-period binaries compared with the field and an unusually largefraction of double-lined systems. This, along with the overall highfrequency of binaries out of the original sample of ~120 sources, can beunderstood as a selection effect, since all these properties tend tofavor the inclusion of the objects in a flux-limited X-ray survey suchas this by making them brighter in X-rays. A short description of thephysical properties of each binary is provided, and a comparison withevolutionary tracks is made using the stellar density as adistance-independent measure of evolution. We rely for this on our newdeterminations of the effective temperature and projected rotationalvelocities of all visible components of the binaries. A number of thesystems merit follow-up observations, including at least four confirmedor probable eclipsing binaries. One of these, RX J0239.1-1028, consistsof a pair of detached K dwarfs and may provide for a potentiallyimportant test of stellar evolution models once the absolute dimensionsof the components are determined. Some of the observations reported herewere obtained with the Multiple Mirror Telescope, a joint facility ofthe Smithsonian Institution and the University of Arizona.
| Binary Search Among X-ray Active Stars South of the Taurus Molecular Cloud.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.1555S&db_key=AST
| Search for young low-mass stars in a ROSAT selected sample south of the Taurus-Auriga molecular clouds
We present results of intermediate resolution spectroscopy of 131optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south ofthe Taurus-Auriga dark cloud complex. These objects have been selectedas candidate young stars from a total of 1084 ROSAT sources in a ~300square degree area. We identify 30 objects as low-mass PMS stars on thebasis of the Li i, lambda 6708 Angstroms doublet in their spectrum, asignature of their young age. All these stars have a spectral type laterthan F7 and show spectral characteristics typical of weak-line andpost-T Tauri stars. The presence of young objects several parsecs awayfrom the regions of ongoing star formation is discussed in the light ofthe current models of T Tauri dispersal. Based on observations made withthe Isaac Newton Telescope operated on the island of La Palma by theRoyal Greenwich Observatory in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofisica de Canarias and with the ESO1.52m telescope on La Silla, Chile, operated by the European SouthernObservatory. Tables 1,2,3,4 are also 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
| Optical high-resolution spectroscopy of ROSAT detected late-type stars south of the Taurus molecular clouds.
We study 111 late-type stars found with optical follow-up observationsof ROSAT All-Sky Survey sources south of the Taurus molecular clouds.Some 30 of them have been claimed to be weak-line T Tauri stars,low-mass pre-main sequence (PMS) stars, based mainly on the presence ofstrong lithium 6708Å absorption in intermediate-resolution(~1Å) spectra. We obtained single-order echelle spectra at bluewavelengths for 106 of these stars, in order to measure their radial androtational velocities, and investigate their angular momentum evolutionand kinematic membership to the Taurus clouds. In addition, we obtainedechelle spectra with high (~0.25Å) resolution for seven stars tomeasure precisely the lithium equivalent width Wlambda_(Li).We find that ~1Å resolution is sufficient in order not tooverestimate Wlambda_(Li), e.g. due to blending. Of our 111stars, 19 are located on the λ Ori cloud, nine of which areK-type stars with lithium in excess of the zero-age-main-sequence (ZAMS)level, i.e. are PMS stars. At least 40 of the remaining 92 off-cloudstars display detectable lithium, 24 of which are lithium-excess stars,i.e. show lithium at least as strong as IC 2602 stars with the samespectral types. Of those 24 stars, nine (25% of the off-cloud stars withdetectable lithium) are PMS stars isolated from cloud material; all havespectral type K, and three of them are spectroscopic binaries. 15off-cloud stars have spectral type G and lithium comparable to IC 2602stars, i.e. may have already arrived on the ZAMS just like G-type IC2602 stars. However, all these 24 off-cloud lithium-excess stars areprobably not older than IC 2602 (~3x10^7^yrs). We discuss possible sitesand modes of origin of the isolated PMS stars south of Taurus.
| New proper motions of pre-main sequence stars in Taurus-Auriga
We present proper motions of 72 T Tauri stars located in the centralregion of Taurus-Auriga (Tau-Aur). These proper motions are taken from anew proper motion catalogue called STARNET. Our sample comprises 17classical T Tauri stars (CTTS) and 55 weak-line T Tauri stars (WTTS),most of the latter discovered by ROSAT. 53 stars had no proper motionmeasurement before. Kinematically, 62 of these stars are members of theassociation. A velocity dispersion of less than 2-3km/s is found whichis dominated by the errors of the proper motions. This velocitydispersion correlates with a spread in distances. Furthermore we presentproper motions of 58 stars located in a region just south of the Taurusmolecular clouds and compare the kinematics of the youngest stars inthis sample (younger than 3.5x10^7^yrs) with the kinematics of thepre-main sequence stars (PMS) in the Taurus-Auriga association. From acomparison of the space velocities we find that the stars in the centralregion of Tau-Aur are kinematically different from the stars in thesouthern part. Among the stars with large proper motions far off theTaurus mean motion we find 2 Pleiades candidates and 7 possible Pleiadesrunaway stars.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| A list of stars with common proper motions.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958AJ.....63..246V&db_key=AST
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Observation and Astrometry data
| Constellation: | Orion |
| Right ascension: | 04h44m20.43s |
| Declination: | +09°41'03.6" |
| Apparent magnitude: | 9.353 |
| Proper motion RA: | 51.3 |
| Proper motion Dec: | -65 |
| B-T magnitude: | 9.985 |
| V-T magnitude: | 9.406 |
Catalogs and designations:
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