Search

Start Over Subject photometry Capability Type Simple Cone Search
4351. SDSS Luminous Red Galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/377/787
Title:
SDSS Luminous Red Galaxies
Short Name:
J/MNRAS/377/787
Date:
21 Oct 2021
Publisher:
CDS
Description:
The data are taken from the Luminous Red Galaxy sample of the Sloan Digital Sky Survey Data Release 4. From the SDSS spectra we compute the five indices Hbeta, Hgamma_F_, Dn(4000), [MgFe]', [Mg1Fe]'. These are matched indices from a synthetic library of spectra containing 31000 different star formation scenarios. From this we can infer probability distributions for a number of properties, such as age, metallicity, etc. The results are presented here as the 5th, 16th, 50th (median), 86th and 95th percentiles of the relevant distribution. The 4391 LRG properties presented here are chosen from the redshift range 0.15<z<0.4 and require all 5 of the above indices to have well-measured values (i.e. no contamination from skylines, bad pixels) Also given are a number of properties that come directly from the SDSS database, such as redshift, velocity dispersion etc. For the luminosity distance calculation (and subsequent mass estimates), we assume a FRW metric, with omega_m_=0.25, omega_lambda_=0.75 and H_0_=73km/s/Mpc.
4352. SDSS M, L, and T dwarfs
ID:
ivo://CDS.VizieR/J/AJ/123/3409
Title:
SDSS M, L, and T dwarfs
Short Name:
J/AJ/123/3409
Date:
21 Oct 2021
Publisher:
CDS
Description:
An extensive sample of M, L, and T dwarfs identified in the Sloan Digital Sky Survey (SDSS) has been compiled. The sample of 718 dwarfs includes 677 new objects (629 M dwarfs and 48 L dwarfs), together with 41 that have been previously published. All new objects and some of the previously published ones have new optical spectra obtained either with the SDSS spectrographs or with the Apache Point Observatory 3.5 m ARC telescope. Spectral types and SDSS colors are available for all objects; approximately 35% also have near-infrared magnitudes measured by 2MASS (Two Micron All Sky Survey) or on the Mauna Kea system. We use this sample to characterize the color-spectral type and color-color relations of late-type dwarfs in the SDSS filters and to derive spectroscopic and photometric parallax relations for use in future studies of the luminosity and mass functions based on SDSS data. We find that the i*-z* and i*-J colors provide good spectral type and absolute magnitude (Mi*) estimates for M and L dwarfs. Our distance estimates for the current sample indicate that SDSS is finding early M dwarfs out to ~1.5kpc, L dwarfs to ~100pc, and T dwarfs to ~20pc. The T dwarf photometric data show large scatter and are therefore less reliable for spectral type and distance estimation.
4353. SDSS & MMT obs. of extremely massive QSOs & gal.
ID:
ivo://CDS.VizieR/J/ApJ/871/57
Title:
SDSS & MMT obs. of extremely massive QSOs & gal.
Short Name:
J/ApJ/871/57
Date:
21 Oct 2021
Publisher:
CDS
Description:
Black hole mass scaling relations suggest that extremely massive black holes (EMBHs) with M_BH_>~10^9.4^M_{sun}_ are found in the most massive galaxies with M_star_>~10^11.6^M_{sun}_, which are commonly found in dense environments, like galaxy clusters. Therefore, one can expect that there is a close connection between active EMBHs and dense environments. Here, we study the environments of 9461 galaxies and 2943 quasars at 0.24<~z<~0.40, among which 52 are extremely massive quasars with log(M_BH_/M_{sun}_)>=~9.4, using Sloan Digital Sky Survey and MMT Hectospec data. We find that, on average, both massive quasars and massive galaxies reside in environments more than ~2 times as dense as those of their less massive counterparts with log(M_BH_/M_{sun}_)<~9.0. However, massive quasars reside in environments about ~2 times less dense than inactive galaxies with log(M_BH_/M_{sun}_)>=9.4, and only about one third of massive quasars are found in galaxy clusters, while about two thirds of massive galaxies reside in such clusters. This indicates that massive galaxies are a much better signpost for galaxy clusters than massive quasars. The prevalence of massive quasars in moderate to low density environments is puzzling, considering that several simulation results show that these quasars appear to prefer dense environments. Several possible reasons for this discrepancy are discussed, although further investigation is needed to obtain a definite explanation.
4354. SDSS nearby galaxies morphologies
ID:
ivo://CDS.VizieR/J/MNRAS/446/3749
Title:
SDSS nearby galaxies morphologies
Short Name:
J/MNRAS/446/3749
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate box/peanut and bar structures in image data of edge-on and face-on nearby galaxies taken from the Sloan Digital Sky Survey (SDSS) to present catalogues containing the surface brightness parameters and the morphology classification. About 1700 edge-on galaxies and 2600 face-on galaxies are selected from SDSS DR7 in the g, r and i-bands. The images of each galaxy are fitted with the model of two-dimensional surface brightness of the Sersic bulge and exponential disk. After removing some irregular data, the box/peanut, bar and other structures are easily distinguished by eye using residual (observed minus model) images. We find 292 box/peanut structures in the 1329 edge-on samples and 630 bar structures in 1890 face-on samples in the i-band, after removing some irregular data. The fraction of box/peanut galaxies is about 22 per cent against the edge-on samples, and that of bar galaxies is about 33 per cent (about 50 per cent if 629 elliptical galaxies are removed) against the face-on samples. Furthermore the strengths of the box/peanuts and bars are evaluated as strong, standard or weak. We find that the strength increases slightly with increasing B/T (bulge-to-total flux ratio), and that the fraction of box/peanuts is generally about a half of that of bars, irrespective of the strength and B/T. Our result supports the idea that a box/peanut is a bar seen edge-on.
4355. SDSS new variables
ID:
ivo://CDS.VizieR/J/AJ/115/296
Title:
SDSS new variables
Short Name:
J/AJ/115/296
Date:
21 Oct 2021
Publisher:
CDS
Description:
The US Naval Observatory 0.2m Flagstaff Astrometric Scanning Transit Telescope (FASTT) was used to obtain astrometric information in 16 equatorial fields in support of the Sloan Digital Sky Survey (SDSS). Each field is approximately 7.6{deg}x3.2{deg} in size and was scanned ~10 times with overlapping CCD strip scans; star positions accurate to +/-50mas in each coordinate and magnitudes good to +/-0.011mag were determined. As an ancillary project, this database was searched for new variables, and the results of that search are presented here. Approximately 1500 new variables have been discovered, and accurate coordinates for ~100 previously identified variables and suspected variables are given.
4356. SDSS observations of Kuiper belt objects
ID:
ivo://CDS.VizieR/J/ApJ/749/10
Title:
SDSS observations of Kuiper belt objects
Short Name:
J/ApJ/749/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Colors of trans-Neptunian objects (TNOs) are used to study the evolutionary processes of bodies in the outskirts of the solar system and to test theories regarding their origin. Here I describe a search for serendipitous Sloan Digital Sky Survey (SDSS) observations of known TNOs and Centaurs. I present a catalog of SDSS photometry, colors, and astrometry of 388 measurements of 42 outer solar system objects. I find weak evidence, at the {approx} 2{sigma} level (per trial), for a correlation between the g - r color and inclination of scattered disk objects and hot classical Kuiper Belt objects. I find a correlation between the g - r color and the angular momentum in the z direction of all the objects in this sample. These findings should be verified using larger samples of TNOs. Light curves as a function of phase angle are constructed for 13 objects. The steepness of the slopes of these light curves suggests that the coherent backscatter mechanism plays a major role in the reflectivity of outer solar system small objects at small phase angles. I find weak evidence for an anticorrelation, significant at the 2{sigma} confidence level (per trial), between the g-band phase-angle slope parameter and the semimajor axis, as well as the aphelion distance, of these objects (i.e., they show a more prominent "opposition effect" at smaller distances from the Sun). However, this plausible correlation should be verified using a larger sample. I discuss the origin of this possible correlation and argue that if this correlation is real it probably indicates that "Sedna"-like objects have a different origin than other classes of TNOs. Finally, I identify several objects with large variability amplitudes.
4357. SDSS photometry in the field of L1457
ID:
ivo://CDS.VizieR/J/AJ/124/2164
Title:
SDSS photometry in the field of L1457
Short Name:
J/AJ/124/2164
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopic and photometric survey of a sample of field stars in the region of the molecular cloud L1457. High-quality coude feed spectra, together with five-band photometry in the Sloan Digital Sky Survey system and near-infrared archival data from the Two Micron All Sky Survey, are used to derive color excesses and distances for the stars. Based on these data, a new distance estimate of 360+/-30pc is derived for the cloud, supporting recent results by K.L. Luhman, 2001ApJ...560..287L. The data further indicate that the north-south velocity gradient seen in the millimeter-wave CO data is mirrored in a distance gradient, with the northern part of the cloud being closer to us. A second, less opaque, layer of extinction is detected at ~80pc. This distance is consistent with the earlier distance estimates to the cloud, based on Na I absorption. We identify this layer with the wall of the hot Local Bubble. Hence, the dense cloud is not, as previously thought, associated with the Local Bubble.
4358. SDSS photometry of HI-selected galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/394/340
Title:
SDSS photometry of HI-selected galaxies
Short Name:
J/MNRAS/394/340
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Parkes Multibeam system and the Sloan Digital Sky Survey to assemble a sample of 195 galaxies selected originally from their HI signature to avoid biases against unevolved or low surface brightness objects. For each source nine intrinsic properties are measured homogeneously, as well as inclination and an optical spectrum. The sample, which should be almost entirely free of either misidentification or confusion, includes a wide diversity of galaxies ranging from inchoate, low surface brightness dwarfs to giant spirals. Despite this diversity there are five clear correlations among their properties. They include a common dynamical mass-to-light ratio within their optical radii, a correlation between surface brightness and luminosity and a common HI surface density. Such correlation should provide strong constrains on models of galaxy formation and evolution.
4359. SDSS photometry of interacting galaxies
ID:
ivo://CDS.VizieR/J/AJ/139/1212
Title:
SDSS photometry of interacting galaxies
Short Name:
J/AJ/139/1212
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Galaxy Evolution Explorer (GALEX) ultraviolet telescope to study stellar populations and star formation morphology in a well-defined sample of 42 nearby optically selected pre-merger interacting galaxy pairs. Galaxy interactions were likely far more common in the early universe than in the present; thus our study provides a nearby well-resolved comparison sample for high-redshift studies. We have combined the GALEX near-ultraviolet (NUV) and far-ultraviolet images with broadband optical maps from the Sloan Digitized Sky Survey to investigate the ages and extinctions of the tidal features and the disks.
4360. SDSS photometry of LMC cluster SL 529
ID:
ivo://CDS.VizieR/J/MNRAS/430/2358
Title:
SDSS photometry of LMC cluster SL 529
Short Name:
J/MNRAS/430/2358
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results on the age and metallicity estimates of the poorly studied Large Magellanic Cloud (LMC) cluster SL 529, from CCD SDSS gr photometry obtained at the Gemini South telescope with the GMOS attached. The cluster main-sequence turnoffs (MSTO) region possesses an extended structure, with an age spread (~0.5Gyr) bigger than the mean age width of known extended MSTO (EMSTO) LMC clusters. We report for the first time a mean cluster age of 2.25Gyr and a mean cluster metallicity of Z=0.004, which place it as the most metal-poor and oldest cluster in the EMSTO LMC cluster group. In addition, the cluster red clump appears to be formed by two concentrations of stars - although it is not clear whether this feature can be caused, in part, by binary interactions and mergers - whereas the cluster core radius of 4.2pc is in excellent agreement with those determined for the previously 12 known EMSTO LMC clusters.