目录
图像
上传图像
DSS Images Other Images
相关文章
Kinematics of Metal-poor Stars in the Galaxy. II. Proper Motions for a Large Nonkinematically Selected Sample
We present a revised catalog of 2106 Galactic stars, selected withoutkinematic bias and with available radial velocities, distance estimates,and metal abundances in the range -4.0<=[Fe/H]<=0.0. This updateof the 1995 Beers & Sommer-Larsen catalog includes newly derivedhomogeneous photometric distance estimates, revised radial velocitiesfor a number of stars with recently obtained high-resolution spectra,and refined metallicities for stars originally identified in the HKobjective-prism survey (which account for nearly half of the catalog)based on a recent recalibration. A subset of 1258 stars in this cataloghave available proper motions based on measurements obtained with theHipparcos astrometry satellite or taken from the updated AstrographicCatalogue (second epoch positions from either the Hubble Space TelescopeGuide Star Catalog or the Tycho Catalogue), the Yale/San Juan SouthernProper Motion Catalog 2.0, and the Lick Northern Proper Motion Catalog.Our present catalog includes 388 RR Lyrae variables (182 of which arenewly added), 38 variables of other types, and 1680 nonvariables, withdistances in the range 0.1 to 40 kpc.
| Kinematics of metal-poor stars in the galaxy
We discuss the kinematic properties of a sample of 1936 Galactic stars,selected without kinematic bias, and with abundances (Fe/H) is less thanor equal to -0.6. The stars selected for this study all have measuredradial velocities, and the majority have abundances determined fromspectroscopic or narrow-/intermediate-band photometric techniques. Incontrast to previous examinations of the kinematics of the metal-poorstars in the Galaxy, our sample contains large numbers of stars that arelocated at distances in excess of 1 kpc from the Galactic plane. Thus, amuch clearer picture of the nature of the metal-deficient populations inthe Galaxy can now be drawn.
| NGC 5266 - an elliptical galaxy with a dust ring
Results of an inquiry into the nature of the southern galaxy NGC 5266are presented. New surface photometry indicates that it is an E4 classelliptical with a narrow and slightly warped dust ring wrapping itsstellar body in the plane containing its short axis. The extensivespectroscopic observations reveal a very fast cylindrical rotation ofthe stellar component (Vmax = 212±7 km s-1)around the short axis and smaller rotation (Vmax =43±16 km s-1) around the long axis. The gas associatedwith dust rotates around the major axis of the galaxy with a velocity of260±10 km s-1. It is shown that the true shape of thestellar component in this galaxy is probably triaxial (nearly oblate).Results from dynamical modeling of the dissipative evolution of gasdisks embedded in triaxial potentials are also reported.
|
提交文章
相关链接
提交链接
下列团体成员
|
观测天体数据
目录:
|
