相关论文: HIPPARCOS results for ROSAT-discovered young stars

We study the kinematics of T Tauri stars (TTS) located in the cores of the Chamaeleon clouds as well as far off these clouds. Our sample comprises 2 early type stars known to be related to Cha I, 6 classical (CTTS) and 6 weak-line T Tauri…

In the SACY (Search for Associations Containing Young-stars) project we try to identify associations of stars younger than the Local Association among HIPPARCOS and/or TYCHO-2 stars later than G0 which are counterparts of the ROSAT X-ray…

Young stars in the solar neighborhood serve as nearby probes of stellar evolution and represent promising targets to directly image self-luminous giant planets. We have carried out an all-sky search for late-type ($\approx$K7$-$M5) stars…

We cross-correlate the Herbig & Bell and Hipparcos Catalogues in order to extract the results for young stellar objects (YSOs). We compare the distances of individual young stars and the distance of their presumably associated molecular…

Young nearby runaway stars are suitable to search for their place of origin and possibly associated objects, for example neutron stars. Tetzlaff, Neuh\"auser & Hohle (2011) selected young ($\le 50$ Myr) runaway star candidates from…

Upper Scorpius is a subgroup of the nearest OB association, Scorpius--Centaurus. Its young age makes it an important association to study star and planet formation. We present parallaxes to 52 low mass stars in Upper Scorpius, 28 of which…

We present new observations of the isolated young stars HD 98800 and CD-33_7795. Pointed ROSAT observations show that their X-ray properties, including X-ray luminosity and variability, are consistent with those of pre-main-sequence (PMS)…

We have identified 317 stars included in the Hipparcos astrometric catalogue which have parallaxes measured to a precision of better than 15%, and whose location in the (M_V, (B-V)_T) diagram implies a metallicity comparable to or less than…

We present results of intermediate resolution spectroscopy of 131 optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south of the Taurus-Auriga dark cloud complex. These objects have been selected as candidate young stars from a…

We have used new parallax measurements, obtained by the Hipparcos satellite, of fifteen nearby, metal-poor stars to re-define the subdwarf main-sequence. All of these stars have parallaxes determined to an accuracy of at least 12 %.…

We present results of a spectroscopic survey of X-ray- and proper motion-selected samples of late-type stars in the Lower Cen-Cru (LCC) and Upper Cen-Lup (UCL) subgroups of the nearest OB association: Sco-Cen. The primary goals of the…

We report on a multiplicity survey of a sample of X-ray selected young stars in the Chamaeleon association. We used speckle-interferometry and direct imaging to find companions in the separation range 0.13" to 6". After correction for…

I discuss results from the recent spectroscopic survey for solar-type pre-MS stars in the Lower Centaurus-Crux (LCC) and Upper Centaurus-Lupus (UCL) OB subgroups by Mamajek, Meyer, & Liebert (2002, AJ, 124, 1670). LCC and UCL are subgroups…

We present first results of a survey for companions among X-ray selected pre-main sequence stars, most of them being weak-line T Tauri stars (WTTS). These T Tauri stars have been identified in the course of optical follow-up observations of…

We present results of an investigation on a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises about 200 G, K, and M stars. Lithium abundances were determined for about…

We present basic observational data and association membership analysis for 45 young and active low-mass stellar systems from the ongoing RECONS photometry and astrometry program at the Cerro Tololo Inter-American Observatory. Most of these…

We present proper motions of 72 T Tauri stars located in the central region of Taurus-Auriga. These proper motions are taken from a new proper motion catalogue called STARNET. Our sample comprises 17 classical T Tauri stars and 55 weak-line…

We present a spectroscopic and kinematic analysis of 79 nearby M dwarfs in 77 systems. All are low-proper-motion southern hemisphere objects and were identified in a nearby star survey with a demonstrated sensitivity to young stars. Using…

Continuous photometric observations of five young stars obtained by the MOST satellite in 2009 and 2010 in the Taurus and Lupus star formation regions are presented. Using light curve modelling under the assumption of internal invariability…

A total of 28 young nearby stars (ages $\leq 60$,Myr) have been observed in the K$_{\rm s}$-band with the adaptive optics imager Naos-Conica of the Very Large Telescope at the Paranal Observatory in Chile. Among the targets are ten visual…