6 research outputs found
Low-Surface-Brightness Galaxies in the Sloan Digital Sky Survey. I. Search Method and Test Sample
In this paper we present results of a pilot study to use imaging data from
the Sloan Digital Sky Survey (SDSS) to search for low-surface-brightness (LSB)
galaxies. For our pilot study we use a test sample of 92 galaxies from the
catalog of Impey et al. (1996) distributed over 93 SDSS fields of the Early
Data Release (EDR). Many galaxies from the test sample are either LSB or dwarf
galaxies. To deal with the SDSS data most effectively a new photometry software
was created, which is described in this paper. We present the results of the
selection algorithms applied to these 93 EDR fields. Two galaxies from the
Impey et al. test sample are very likely artifacts, as confirmed by follow-up
imaging. With our algorithms, we were able to recover 87 of the 90 remaining
test sample galaxies, implying a detection rate of 96.5%. The three
missed galaxies fall too close to very bright stars or galaxies. In addition,
42 new galaxies with parameters similar to the test sample objects were found
in these EDR fields (i.e., 47% additional galaxies). We present the main
photometric parameters of all identified galaxies and carry out first
statistical comparisons. We tested the quality of our photometry by comparing
the magnitudes for our test sample galaxies and other bright galaxies with
values from the literature. All these tests yielded consistent results. We
briefly discuss a few unusual galaxies found in our pilot study, including an
LSB galaxy with a two-component disk and ten new giant LSB galaxies.Comment: 36 pages, 16 figures, accepted for publication by AJ, some figures
were bitmapped to reduce the siz
Strong emission line H II galaxies in the Sloan Digital Sky Survey. I. Catalog of DR1 objects with oxygen abundances from Te measurements measurements
We present the first edition of the SDSS H II
galaxies with Oxygen abundances Catalog (SHOC),
which is a listing of strong emission-line
galaxies (ELGs) from the Sloan Digital Sky Survey
(SDSS). Oxygen abundances have been obtained
with the classic Te method. We
describe the method exploiting the SDSS database
to construct this sample. The selection
procedures are described and discussed in detail,
as well as some problems encountered in the
process of deriving reliable emission line
parameters. The method was applied to the SDSS
Data Release 1 (DR1). We present 612 SDSS
emission-line galaxies (624 separate SDSS
targets in total), for which the oxygen
abundances 12+log(O/H) have rms uncertainties
‚‚lt;=0.20 dex. The subsample of 263 ELGs (272
separate SDSS targets) have an uncertainty
‚‚lt;=0.10 dex, while 459 ELGs (470 separate
SDSS targets) have an uncertainty ‚‚lt;=0.15
dex. The catalog includes the main parameters of
all selected ELGs, the intensities and
equivalent widths of hydrogen and oxygen emission
lines, as well as oxygen abundances with their
uncertainties. The information on the presence
of Wolf-Rayet blue and/or red bumps in 109
galaxies is also included. With the use of
combined g, r, i SDSS images we performed visual
morphological classification of all SHOC
galaxies. Four hundred sixty-one galaxies (~75%)
are classified as confident or probable blue
compact galaxies (BCG/BCG?), 78 as irregular
ones, 20 as low surface brightness galaxies
(LSBG), 10 as obviously interacting, and 43 as
spiral galaxies. In creating the catalog, 30
narrow-line active galactic nuclei and 69 LINERs
were also identified; these are also presented
apart of the main catalog. We outline briefly the
content of the catalog, and the prospects of its
use for statistical studies of the star
formation and chemical evolution issues. Some of
these studies will be presented in the
forthcoming paper. Finally, we show that the
method presented by Kniazev et al. for
calculating O+/H+ using
intensities of the [O II] ‚‚lambda;‚‚lambda;7320,
7330 lines for SDSS emission-line spectra in the
absence of [O II] ‚‚lambda;3727 line appears to
yield reliable results over a wide range of
studied oxygen abundances:
7.10‚‚lt;12+log(O/H)‚‚lt;8.5