Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
Southern Sky Redshift Survey - The catalog
The catalog of radial velocities for galaxies which comprise thediameter-limited sample of the Southern Sky Redshift Survey ispresented. It consolidates the data of observations carried out at theLas Campanas Observatory, Observatorio Nacional, and South AfricanAstronomical Observatory. The criteria used for the sample selection aredescribed, as well as the observational procedures and the techniqueutilized to obtain the final radial velocities. The intercomparisonbetween radial velocity measurements from different telescopes indicatesthat the final data base is fairly homogeneous with a typical error ofabout 40 km/s. The sample is at present 90 percent complete, and themissing galaxies are predominantly objects with very low surfacebrightness for which it is very difficult to obtain optical redshifts.
| The optical spectra of central galaxies in southern clusters Evidence for star formation
A collection of 21 elliptical galaxies is observed, of which nine are atthe center of clusters with cooling flows, and it is found that 12 haveextended optical line emission. The spectra show line ratios indicatinglow ionization and are qualitatively similar to those observed in othercooling flows. A problem with the production of the large observed lineluminosities is highlighted and explained by some ongoing star formationwith the initial mass function of a disk galaxy. The rate of such starformation is as high as 100 solar masses/yr in the case of PKS 0745 -191, and in all the galaxies there is quantitative agreement between theH-beta line flux and the 4000-A break measured from the blue spectra.Most of the gas (more than 90 percent) must cool from X-ray temperaturesand form low-mass objects without producing any detectable optical lineradiation or hot young stars.
| Southern Galaxy Catalogue.
Not Available
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
Katalógusok és elnevezések:
|
