Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The impact of IUE observations on our knowledge about galaxies and quasars
Observations of extragalactic objects with IUE are discussed. Ellipticalgalaxies show the presence of very hot stars which are probably highlyevolved horizontal branch objects, although the observations are notadequate to rule out young OB stars. Spiral and irregular galaxies oftenshow evidence of young OB stars although the nucleus of M31 is verysimilar to elliptical galaxies. Several narrow emission line galaxiesappear to have nonthermal continua. Observations of Seyfert galaxiespermit detailed studies of the continua and line ratios such as L alphato H beta to be made. Unlike quasars, there is evidence for dust basedon the 2175 A feature. The problem of understanding Seyfert galaxyspectra is no easier than that for quasars although observed variabilityin the broad lines may present useful clues. Observations of highredshift quasars with IUE allow spectra to be obtained down to restwavelengths of a few hundred Angstroms and provide information about theamount of ionizing flux. Observations of low redshift quasars can beused to test whether the myriads of absorption lines seen below L alphain high redshift quasars are indeed produced by intergalactic clouds andhalos of intervening galaxies.
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
Каталоги и обозначения:
|
