10 research outputs found
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
Optical and HI properties of isolated galaxies in the 2MIG catalog. I. General relationships
We analyze empirical relationships between the optical, near infrared, and HI
characteristics of isolated galaxies from the 2MIG Catalog covering the entire
sky. Data on morphological types, K_S-, and B-magnitudes, linear diameters, HI
masses, and rotational velocities are examined. The regression parameters,
dispersions, and correlation coefficients are calculated for pairs of these
characteristics. The resulting relationships can be used to test the
hierarchical theory of galaxy formation through numerous mergers of cold dark
matter.Comment: 18 pages, 11 figures, 5 table
Survey of H-alpha emission from thirty nearby dwarf galaxies
Measurements of the H-alpha flux from 30 neighboring dwarf galaxies are
presented. After correction for absorption, these fluxes are used to estimate
the star formation rate (SFR). The SFR for 18 of the galaxies according to the
H-alpha emission are compared with estimates of the SFR from FUV magnitudes
obtained with the GALEX telescope. These are in good agreement over the range
log[SFR] = [-3,0]M sun/yr.Comment: 18 pages, 10 figures, 3 table
On the kinematics of the Local cosmic void
We collected the existing data on the distances and radial velocities of
galaxies around the Local Void in the Aquila/Hercules to examine the peculiar
velocity field induced by its underdensity. A sample of 1056 galaxies with
distances measured from the Tip of the Red Giant Branch, the Cepheid
luminosity, the SNIa luminosity, the surface brightness fluctuation method, and
the Tully-Fisher relation has been used for this purpose. The amplitude of
outflow is found to be ~300 km/s. The galaxies located within the void produce
the mean intra-void number density about 1/5 of the mean external number
density of galaxies. The void's population has a lower luminosity and a later
morphological type with the medians: M_B = -15.7^m and T = 8 (Sdm),
respectively.Comment: Version 1. 14 pages, 8 figures, 2 tables. Accepted to Astrophysics,
Volume 54, Issue
Infrared composition of the Large Magellanic Cloud
The evolution of galaxies and the history of star formation in the Universe
are among the most important topics in today's astrophysics. Especially, the
role of small, irregular galaxies in the star-formation history of the Universe
is not yet clear. Using the data from the AKARI IRC survey of the Large
Magellanic Cloud at 3.2, 7, 11, 15, and 24 {\mu}m wavelengths, i.e., at the
mid- and near-infrared, we have constructed a multiwavelength catalog
containing data from a cross-correlation with a number of other databases at
different wavelengths. We present the separation of different classes of stars
in the LMC in color-color, and color-magnitude, diagrams, and analyze their
contribution to the total LMC flux, related to point sources at different
infrared wavelengths
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
Dwarf Galaxies of the Local Group
The Local Group (LG) dwarf galaxies offer a unique window to the detailed
properties of the most common type of galaxy in the Universe. In this review, I
update the census of LG dwarfs based on the most recent distance and radial
velocity determinations. I then discuss the detailed properties of this sample,
including (a) the integrated photometric parameters and optical structures of
these galaxies, (b) the content, nature and distribution of their ISM, (c)
their heavy-element abundances derived from both stars and nebulae, (d) the
complex and varied star-formation histories of these dwarfs, (e) their internal
kinematics, stressing the relevance of these galaxies to the dark-matter
problem and to alternative interpretations, and (f) evidence for past, ongoing
and future interactions of these dwarfs with other galaxies in the Local Group
and beyond. To complement the discussion and to serve as a foundation for
future work, I present an extensive set of basic observational data in tables
that summarize much of what we know, and what we still do not know, about these
nearby dwarfs. Our understanding of these galaxies has grown impressively in
the past decade, but fundamental puzzles remain that will keep the Local Group
at the forefront of galaxy evolution studies for some time.Comment: 66 pages; 9 figures; 8 table