اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدLenticular galaxies at the outskirts of the Leo II group: NGC 3599 and NGC 3626
190
0
0.0
(
0
)
تأليف
O. K. Silchenko
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We have studied unbarred S0 galaxies, NGC 3599 and NGC 3626, the members of the X-ray bright group Leo II, by means of 3D spectroscopy, long-slit spectroscopy, and imaging, with the aim to identify epoch and mechanismsof their transformation from spirals. Both galaxies have appeared to bear a complex of features resulting obviously from minor merging: decoupled gas kinematics, nuclear starforming rings, and multi-tiered oval large-scale stellar disks. The weak-emission line nucleus of NGC 3599 bears all signs of the Seyfert activity, according to the line-ratio diagnostics of the gas excitation mechanism. After all, we conclude that the transformation of these lenticular galaxies has had place about 1-2 Gyr ago, through the gravitational mechanisms not related to hot intragroup medium of Leo II.
قيم البحث
اقرأ أيضاً
The kinematics, structure, and stellar population properties in the centers of two brightest early-type galaxies of the Leo II group, NGC 3607 and NGC 3608, are studied by means of integral-field spectroscopy. The kinematically distinct areas in the
centers of these galaxies, with radii of 6 and 5 respectively, are found also to be chemically distinct. These stellar structures are characterized by enhanced magnesium-line strength in the integrated spectra. However, we have not found any mean stellar age differences between the decoupled cores and their outskirts. Analysis of the two-dimensional line-of-sight velocity fields reveals systematic turns of the kinematical major axes near the nuclei of both galaxies; in NGC 3608 the ionized gas rotates in the orthogonal plane with respect to the stellar component rotation. By taking into account some morphological features, we conclude that both NGC 3607 and NGC 3608 have large triaxial stellar spheroids. We argue that the magnesium-enhanced cores are not circumnuclear disks; instead they resemble rather compact triaxial structures which may be a cause of formation of polar disks around them - a gaseous one in NGC 3608 and a stellar-gaseous one in NGC 3607. In the latter galaxy the star formation is perhaps still proceeding over the polar disk.
We present a compilation of galaxies in the NGC 1023 Group, an accumulation of late-type galaxies at a distance of 10 Mpc. Members at high and intermediate luminosities were identified from their spectroscopic velocities. Members at low luminosities
were identified from their morphologies on wide-field CCD images. The faint-end slope is in the range -1.27 < alpha < -1.12. There is evidence for two dwarf galaxy populations: one in the halo of NGC 1023 that is dominated by dwarf elliptical galaxies, and one in the infall region surrounding NGC 1023 that contains mainly dwarf irregular galaxies. Similar distinctive populations are observed in the Local Group.
By means of panoramic spectroscopy at the SAO RAS BTA telescope, we investigated the properties of stellar populations in the central regions of five early-type galaxies -- the NGC 524 group members. The evolution of the central regions of galaxies l
ooks synchronized: the average age of stars in the bulges of all the five galaxies lies in the range of 3--6 Gyr. Four of the five galaxies revealed synchronized bursts of star formation in the nuclei 1--2 Gyr ago. The only galaxy, in which the ages of stellar population in the nucleus and in the bulge coincide (i.e. the nuclear burst of star formation did not take place) is NGC 502, the farthest from the center of the group of all the galaxies studied.
Stellar archeology of nearby LINER galaxies may reveal if there is a stellar young population that may be responsible for the LINER phenomenon. We show results for the classical LINER galaxies NGC 4579 and NGC 4736 and find no evidence of such populations.
Members of the NGC 524 group of galaxies are studied using data obtained on the 6m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, with the SCORPIO reducer in an imaging mode. Surface photometry has been carried
out and parameters of the large-scale galactic components - disks and bulges - have been determined for the six largest galaxies of the group. A lower than expected percentage of bars and high percentage of ring structures were found. Integrated B-V colours for a hundred of dwarf galaxies in the vicinity (within 30 kpc) of the six largest galaxies of the group have been measured. A considerable number of blue irregular galaxies with ongoing star formation is found among dwarf satellites of the lenticular galaxies of the group. The luminosity function for the dwarf galaxies of the group suggests that the total mass of the group is not very high, and that the X-ray emitting gas observed around NGC 524 relates to the central galaxy and not to the group as a whole.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
