Ýçindekiler
Görüntüler
Resim Yükleyin
DSS Images Other Images
Ýlgili Makaleler
The Brown Dwarf Kinematics Project. II. Details on Nine Wide Common Proper Motion Very Low Mass Companions to Nearby Stars
We report on nine wide common proper motion systems containing late-typeM, L, or T companions. We confirm six previously reported companions,and identify three new systems. The ages of these systems are determinedusing diagnostics for both stellar primaries and low-mass secondariesand masses for the secondaries are inferred using evolutionary models.Of our three new discoveries, the M3+T6.5 pair G 204-39 and SDSSJ1758+4633 has an age constrained to 0.5-1.5 Gyr making the secondary apotentially useful brown dwarf benchmark. The G5+L4 pair G 200-28 andSDSS J1416+5006 has a projected separation of ~25,000 AU making it oneof the widest and lowest binding energy systems known to date. Thesystem containing NLTT 2274 and SDSS J0041+1341 is an older M4+L0(>4.5 Gyr) pair which shows H? activity in the secondary butnot the primary making it a useful tracer of age/mass/activity trends.Two of the nine systems have discrepant component ages that emerge fromstellar or ultracool diagnostics indicating possible shortcomings in ourunderstanding of the age diagnostics of stars and brown dwarfs. We finda resolved binary frequency for widely separated (>100 AU) low-masscompanions (i.e., at least a triple system) which is at least twice thefrequency found for the field ultracool dwarf population. The ratio oftriples to binaries and quadruples to binaries is also high for thissample: 3:5 and 1:4, respectively, compared to 8 pc sample values of 1:4and 1:26. The additional components in these wide companion systemsindicates a formation mechanism that requires a third or fourthcomponent to maintain gravitational stability or facilitate the exchangeof angular momentum. The binding energies for the nine multiplesdiscussed in this text are among the lowest known for wide low-masssystems, suggesting that weakly bound, low-to-intermediate mass (0.2 Msun < M tot< 1.0 M sun) multiplescan form and survive to exist in the field (1-8 Gyr).This paper includes data gathered with the 6.5 meter Magellan Telescopeslocated at Las Campanas Observatory, Chile.This paper makes use of data obtained with the telescopes operated bythe SMARTS consortium.
| Visual multiples. VIII - 1000 MK types
A total of 1000 new classifications are given for stars brighter than B= 8.0 mag in the Aitken double star catalog. The classificationssupplement 865 classifications obtained in 1981 and 1984. Among thenewly discovered stars are 12 new Ap stars, eight Lambda Bootis stars,one Ba II star, and 60 Am stars. A detailed list of the newclassifications is given.
| Four-colour and H beta photometry of southern B stars at high galactic latitudes
Four-color and H beta photometry has been obtained for 105 early-type HDstars with galactic latitudes less than -45 deg. They are mostly late Bstars of luminosity class V to III. Two new Am stars and several Ap orBp stars are detected photometrically. Absolute magnitudes aredetermined from the photometry and from MK types where available. Theinterstellar reddening of many of the more distant stars is very small,suggesting either the existence of undetected peculiar stars in thesample or that there are areas of effectively zero reddening at highsouthern galactic latitudes.
| A finding list of stars of spectral type A7 and earlier in regions at high galactic latitudes. VI. Near South Galactic Pole.
Not Available
| Faint blue stars in the region near the South Galactic Pole.
Not Available
|
Yeni bir Makale Öner
Ýlgili Baðlantýlar
Yeni Bir Baðlantý Öner
sonraki gruplarýn üyesi:
|
Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 23h24m01.59s |
| Yükselim: | -27°16'51.1" |
| Görünürdeki Parlaklýk: | 7.768 |
| Uzaklýk: | 181.488 parsek |
| özdevim Sað Açýklýk: | 20.7 |
| özdevim Yükselim: | 7.7 |
| B-T magnitude: | 7.752 |
| V-T magnitude: | 7.767 |
Kataloglar ve belirtme:
|
