Ýçindekiler
Görüntüler
Resim Yükleyin
DSS Images Other Images
Ýlgili Makaleler
Search for associations containing young stars (SACY). I. Sample and searching method
We report results from a high-resolution optical spectroscopic surveyaimed to search for nearby young associations and young stars amongoptical counterparts of ROSAT All-Sky Survey X-ray sources in theSouthern Hemisphere. We selected 1953 late-type (B-V~≥~0.6),potentially young, optical counterparts out of a total of 9574 1RXSsources for follow-up observations. At least one high-resolutionspectrum was obtained for each of 1511 targets. This paper is the firstin a series presenting the results of the SACY survey. Here we describeour sample and our observations. We describe a convergence method in the(UVW) velocity space to find associations. As an example, we discuss thevalidity of this method in the framework of the β Pic Association.
| The Solar Neighborhood. VII. Discovery and Characterization of Nearby Multiples in the CTIO Parallax Investigation
We report the discovery of eight new multiple star systems among 191stellar systems targeted for parallax determinations in the RECONS(Research Consortium on Nearby Stars) southern parallax program, CTIOPI(Cerro Tololo Inter-American Observatory Parallax Investigation). Theeight new companions have separations of 1.42" to 14.90" andinstrumental magnitude differences at VRI of 0.06-6.07 mag. Orbitalmotion has not been detected in any of these systems. These newcompanions increase the multiplicity fraction of this sample, made upprimarily of nearby (less than 25 pc) M dwarfs, to 15%. Comparison withsamples that have been more completely scrutinized for companionsindicates that probably only half of all multiples have so far beendiscovered. Given the large number of frames acquired for theastrometric series, the eight new systems and 16 known multiples havebeen searched for variability at VRI during the 3 year duration ofCTIOPI. A flare has been detected in the secondary of the RX J1132-264system, while at least one component in the GJ 2006 system is a probablelong-term variable. Variables were detected in only 9% of the systemssearched, primarily as a result of the restrictive 0.05 mag thresholdrequired for variability confirmation.
| Hipparcos astrometry for 257 stars using Tycho-2 data
We present improved Hipparcos astrometry for 257 Hipparcos stars,resolved into 342 components. For 64 of the stars no astrometry wasobtained in the Hipparcos Catalogue, while for the remaining starsadditional components have been added by this solution or the positionshave been revised considerably. We have used the published Hipparcostransit data for the new solutions, together with results from thesecond reduction of the Tycho data for defining better initial values.Based on observations made with the ESA Hipparcos astrometry satellite.Table 3 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Spectroscopic observations of interesting southern stars noted on southern objective-prism plates.
Abstract image available at:http://adsabs.harvard.edu/abs/1974ApJ...191..685S
|
Yeni bir Makale Öner
Ýlgili Baðlantýlar
Yeni Bir Baðlantý Öner
sonraki gruplarýn üyesi:
|
Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Akrep |
| Sað Açýklýk: | 16h45m16.97s |
| Yükselim: | -38°48'33.2" |
| Görünürdeki Parlaklýk: | 9.924 |
| özdevim Sað Açýklýk: | -18.6 |
| özdevim Yükselim: | -56.3 |
| B-T magnitude: | 11.562 |
| V-T magnitude: | 10.06 |
Kataloglar ve belirtme:
|
