1,311 research outputs found
Bright 22 m Excess Candidates from WISE All-Sky Catalog and Hipparcos Main Catalog
In this paper we present a catalog which includes 141 bright candidates
( mag, V band) showing the infrared (IR) excess at 22 m. Of
which, 38 stars are known IR excess stars or disk, 23 stars are double or
multiple stars and 4 are Be stars. While the remaining more than 70 stars are
identified as the 22 m excess candidates in our work. The criterion of
selecting candidates is . All these candidates are selected
from \emph{WISE} All-sky data cross-correlated with \emph{Hipparcos} Main
Catalog and the likelihood-ratio technique is employed. Considering the effect
of background, we introduce the \emph{IRAS} 100 m level to exclude the
high background. We also estimated the coincidence probability of these
sources. In addition, we presented the optical to mid-infrared SEDs and optical
images of all the candidates, and gave the observed optical spectra of 6 stars
with NAOC's 2.16-m telescope. To measure for the dust amount around each star,
the fractional luminosity is also provided. We also test whether our method of
selecting IR excess stars can be used to search for extra-solar planets, we
cross-matched our catalog with known IR-excess stars having planets but none is
matched. Finally, we give the fraction of stars showing IR-excess for different
spectral type of main-sequence stars.Comment: 45 pages, 16 figures, 4 tables. Accepted for publication in ApJ
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An Hα Imaging Survey of All (Ultra)luminous Infrared Galaxies at Decl. ≥ -30 in the GOALS Sample
This paper presents the result of Hα imaging for luminous and ultraluminous infrared galaxies. It is a complete subsample of the Great Observatories All-sky LIRG Survey (GOALS) with decl. ≥ -30 , and consists of 148 galaxies with log(L IR/L ) ≥ 11.0. All the Hα images were carried out using the 2.16 m telescope at the Xinglong Station of the National Astronomy Observatories, Chinese Academy of Sciences (NAOC), during the year from 2006 to 2009. We obtained the pure Hα luminosity for each galaxy and corrected the luminosity for [N ii] emission, filter transmission, and extinction. We also classified these galaxies based on their morphology and interaction. We found that the distribution of star-forming regions in these galaxies is related to this classification. As the merging process advanced, these galaxies tended to have a more compact distribution of star-forming regions, higher L IR, and warmer IR-color (f 60/f 100). These results imply that the degree of dynamical disturbance plays an important role in determining the distribution of a star-forming region
An H Imaging Survey of the Low-surface-brightness Galaxies Selected from the Fall Sky Region of the 40 ALFALFA \ion{H}{1} Survey
We present the observed H flux and derived star formation rates
(SFRs) for a fall sample of lowsurfacebrightness galaxies (LSBGs). The
sample is selected from the fall sky region of the 40 ALFALFA {\ion{H}{1}}
survey SDSS DR7 photometric data, and all the images were
obtained using the 2.16 m telescope, operated by the National Astronomy
Observatories, Chinese Academy of Sciences. A total of 111 LSBGs were observed
and flux was measured in 92 of them. Though almost all the LSBGs in
our sample are {\ion{H}{1}}rich, their SFRs derived from the extinction and
filtertransmissioncorrected flux, are less than
1M_{\sun}.
LSBGs and star forming galaxies have similar {\ion{H}{1}} surface densities,
but LSBGs have much lower SFRs and SFR surface densities than starforming
galaxies. Our results show that LSBGs deviate from the Kennicutt-Schmidt law
significantly, which indicate that they have low star formation efficiency. The
SFRs of LSBGs are close to average SFRs in Hubble time and support the previous
arguments that most of the LSBGs are stable systems and they tend to seldom
contain strong interactions or major mergers during their star formation
histories
An H Imaging Survey of the Low-surface-brightness Galaxies Selected from the Fall Sky Region of the 40 ALFALFA \ion{H}{1} Survey
We present the observed H flux and derived star formation rates
(SFRs) for a fall sample of lowsurfacebrightness galaxies (LSBGs). The
sample is selected from the fall sky region of the 40 ALFALFA {\ion{H}{1}}
survey SDSS DR7 photometric data, and all the images were
obtained using the 2.16 m telescope, operated by the National Astronomy
Observatories, Chinese Academy of Sciences. A total of 111 LSBGs were observed
and flux was measured in 92 of them. Though almost all the LSBGs in
our sample are {\ion{H}{1}}rich, their SFRs derived from the extinction and
filtertransmissioncorrected flux, are less than
1M_{\sun}.
LSBGs and star forming galaxies have similar {\ion{H}{1}} surface densities,
but LSBGs have much lower SFRs and SFR surface densities than starforming
galaxies. Our results show that LSBGs deviate from the Kennicutt-Schmidt law
significantly, which indicate that they have low star formation efficiency. The
SFRs of LSBGs are close to average SFRs in Hubble time and support the previous
arguments that most of the LSBGs are stable systems and they tend to seldom
contain strong interactions or major mergers during their star formation
histories
The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap I. The Spectroscopic Redshift Catalog
We present a spectroscopic redshift catalog from the LAMOST Complete
Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap
(SGC), which is designed to observe all sources (Galactic and extra-galactic)
by using repeating observations with a limiting magnitude of in
two fields. The project is mainly focusing on the completeness of
LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source
selection methods and the basic performance parameters of LAMOST telescope. In
both fields, more than 95% of galaxies have been observed. A post-processing
has been applied to LAMOST 1D spectrum to remove the majority of remaining sky
background residuals. More than 10,000 spectra have been visually inspected to
measure the redshift by using combinations of different emission/absorption
features with uncertainty of . In total, there are 1528
redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570
redshifts (569 absorption and 1001 emission line galaxies) in Field B have been
measured. The results show that it is possible to derive redshift from low SNR
galaxies with our post-processing and visual inspection. Our analysis also
indicates that up to 1/4 of the input targets for a typical extra-galactic
spectroscopic survey might be unreliable. The multi-wavelength data analysis
shows that the majority of mid-infrared-detected absorption (91.3%) and
emission line galaxies (93.3%) can be well separated by an empirical criterion
of . Meanwhile, a fainter sequence paralleled to the main population
of galaxies has been witnessed both in / and /
diagrams, which could be the population of luminous dwarf galaxies but
contaminated by the edge-on/highly inclined galaxies ().Comment: 19 pages, 14 figures, 2 MRT, accepted by ApJ
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