314 research outputs found
SDSSJ124155.33+114003.7 -- a Missing Link Between Compact Elliptical and Ultracompact Dwarf Galaxies
We report the discovery of a compact object (R_e = 32 pc, M_B = -12.34 mag)
at a projected distance of 9 kpc from Messier 59, a giant elliptical in the
Virgo cluster. Using HST imaging and SDSS spectroscopy, both available in the
Virtual Observatory, we find that this object has a blue core containing
one-quarter of the light, and a redder n=1 Sersic envelope, as well as
luminosity-weighted age of 9.3 +/- 1.4 Gyr, a metallicity of -0.03 +/- 0.04 dex
and a velocity dispersion of 48 +/- 5 km/s. While ultra-compact dwarfs (UCDs)
in the face-on view of the Fundamental Plane are found to form a sequence
connecting the highest-luminosity globular clusters with the lowest-luminosity
dwarf ellipticals, the compact object near M59 lies in between this UCD
sequence and the positions of compact ellipticals. Its stellar age,
metallicity, and effective surface brightness are similar to low-luminosity
ellipticals and lenticulars, suggesting that SDSSJ124155.33+114003.7 is a
result of the tidal stripping of such an object.Comment: 5 pages, 4 figures, accepted to MNRAS Letter
A complex stellar line-of-sight velocity distribution in the lenticular galaxy NGC 524
We present the detailed study of the stellar and gaseous kinematics of the
luminous early-type galaxy NGC 524 derived from the long-slit spectroscopic
observations obtained with the Russian 6-m telescope and the IFU data from the
SAURON survey. The stellar line-of-sight velocity distribution (LOSVD) of NGC
524 exhibits strong asymmetry. We performed the comprehensive analysis of the
LOSVD using two complementary approaches implemented on top of the nbursts full
spectral fitting technique, (a) a nonparametric LOSVD recovery and (b) a
parametric recovery of two Gaussian kinematical components having different
stellar populations. We discuss the origin of the complex stellar LOSVD of NGC
524.Comment: 6 pages, 4 figures, proceedings of 8th SCSLSA, to appear in Baltic
Astronom
Search For Companions Of Nearby Isolated Galaxies
The radial velocities are measured for 45 galaxies located in the
neighborhoods of 29 likely isolated galaxies in a new catalog. We find that
about 85% of these galaxies actually are well isolated objects. 4% of nearby
galaxies with V_LG<3500 km/s are this kind of cosmic "orphan".Comment: 7 pages, 2 figure
A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory
Compact elliptical galaxies are characterized by small sizes and high stellar
densities. They are thought to form through tidal stripping of massive
progenitors. However, only a handful of them were known, preventing us from
understanding the role played by this mechanism in galaxy evolution. We present
a population of 21 compact elliptical galaxies gathered with the Virtual
Observatory. Follow-up spectroscopy and data mining, using high-resolution
images and large databases, show that all the galaxies exhibit old metal-rich
stellar populations different from those of dwarf elliptical galaxies of
similar masses but similar to those of more massive early-type galaxies,
supporting the tidal stripping scenario. Their internal properties are
reproduced by numerical simulations, which result in compact dynamically hot
remnants resembling the galaxies in our sample.Comment: 26 pages, 5 figures, 2 tables. Science in press, published in Science
Express on 1/Oct/2009. Full resolution figures in the supplementary online
material are available from the Science Magazine web-sit
Star Formation History at the Centers of Lenticular Galaxies with Bars and Purely Exponential Outer Disks from SAURON Data
We have investigated the stellar population properties in the central regions
of a sample of lenticular galaxies with bars and single-exponential outer
stellar disks using the data from the SAURON integral-field spectrograph
retrieved from the open Isaac Newton Group Archive. We have detected chemically
decoupled compact stellar nuclei with a metallicity twice that of the stellar
population in the bulges in seven of the eight galaxies. A starburst is
currently going on at the center of the eighth galaxy and we have failed to
determine the stellar population properties from its spectrum. The mean stellar
ages in the chemically decoupled nuclei found range from 1 to 11 Gyr. The
scenarios for the origin of both decoupled nuclei and lenticular galaxies as a
whole are discussed.Comment: 10 pages, 4 figures, a slightly edited version of the paper published
by Astronomy Letters, v. 37, no.1, 201
On the angular distribution of extensive air showers
Angular distributions of extensive air showers with different number of
charged particles in the range 2.5x10^5--4x10^7 are derived using the
experimental data obtained with the EAS MSU array. Possible approximations of
the obtained distributions with different empiric functions available in
literature, are analysed. It is shown that the exponential function provides
the best approximation of the angular distributions in the sense of the
chi-squared criterion.Comment: 5 pages including 1 figur
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