- ID:
- ivo://CDS.VizieR/J/A+A/478/701
- Title:
- Color excess of SDSS quasars with DLA systems
- Short Name:
- J/A+A/478/701
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed the spectroscopic and photometric database of the 5th data release of the Sloan Digital Sky Survey (SDSS) to search for evidence of the quasar reddening produced by dust embedded in intervening damped Ly{alpha} (DLA) systems. From a list of 5164 quasars in the interval of emission redshift 2.25<=z_e_<=3.5 and SDSS spectra with signal-to-noise ratio SNR>~4, we built up an "absorption sample" of 248 QSOs with a single DLA system in the interval of absorption redshift 2.2<z_a_<=3.5 and a "pool" of 1959 control QSOs without DLA systems or strong metal systems. For each QSO of the absorption sample we extracted from the pool a subset of control QSOs that are closest in redshift and magnitude.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/423/755
- Title:
- Color-Induced Displacement double stars in SDSS
- Short Name:
- J/A+A/423/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first successful application of the astrometric color-induced displacement technique (CID, the displacement of the photocenter between different band-passes dur to a varying contribution of differently colored components to the total light), originally proposed by Wielen (1996A&A...314..679W) for discovering unresolved binary stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/500/714
- Title:
- Color-magnitude relation in CL 1358+62
- Short Name:
- J/ApJ/500/714
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a large, multicolor mosaic of HST WFPC2 images to measure the colors and morphologies of 194 spectroscopically confirmed members of the rich galaxy cluster CL 1358+62 at z=0.33. We study the color-magnitude (CM) relation as a function of radius in the cluster to a limit of 4.6' from the center, equivalent to 1.6h^-1^_50_Mpc. The intrinsic scatter in the rest-frame B-V CM relation of the elliptical galaxies is very small, ~0.022mag. The CM relation of the ellipticals does not depend significantly on the distance from the cluster center. In contrast, the CM relation for the S0 galaxies does depend on radius: the S0's in the core follow a CM relation similar to that of the ellipticals, but at large radii (R>0.7h^-1^_50_Mpc) the S0's are systematically bluer and the scatter in the CM relation approximately doubles, to ~0.043mag. The blueing of the S0's at large radii is significant at the 95% confidence level. These results imply that the S0 galaxies in the outer parts of the cluster have formed stars more recently than the S0's in the inner parts.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/368
- Title:
- Color-magnitude relations of galaxies in CDFs
- Short Name:
- J/ApJ/720/368
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We extend color-magnitude relations for moderate-luminosity X-ray active galactic nucleus (AGN) hosts and non-AGN galaxies through the galaxy formation epoch (z~1-4) in the Chandra Deep Field-North and Chandra Deep Field-South (CDF-N and CDF-S, respectively; jointly CDFs) surveys. This study was enabled by the deepest available X-ray data from the 2Ms CDF surveys as well as complementary ultradeep multiwavelength data in these regions. We utilized analyses of color-magnitude diagrams (CMDs) to assess the role of moderate-luminosity AGNs in galaxy evolution.
- ID:
- ivo://CDS.VizieR/J/A+AS/109/487
- Title:
- Color-magnitude study of M 22
- Short Name:
- J/A+AS/109/487
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new photographic C-M diagram for the globular cluster M 22 based on automatic plate measurements has been obtained. It reaches the main sequence turn-off at V=~17.1mag, (B-V)=~0.75.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/149
- Title:
- Color-metallicity relations. II. M87 GCs
- Short Name:
- J/ApJ/743/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We here propose a new photometric technique to probe the possible nonlinear nature of globular clusters (GCs) color-metallicity relations (CMRs). In essence, a color distribution of GCs is a "projected" distribution of their metallicities. Since the form of CMRs hinges on which color is used, the shape of color distributions varies depending significantly on the colors. Among other optical colors, the u-band related colors (e.g., u-g and u-z) are theoretically predicted to exhibit significantly less inflected CMRs than other preferred CMRs (e.g., for g-z). As a case study, we performed the Hubble Space Telescope (HST)/WFPC2 archival u-band photometry for the M87 (NGC 4486) GC system with confirmed color bimodality. We show that the u-band color distributions are significantly different from that of g-z and consistent with our model predictions. With more u-band measurements, this method will support or rule out the nonlinear CMR scenario for the origin of GC color bimodality with high confidence.
- ID:
- ivo://CDS.VizieR/J/ApJS/256/29
- Title:
- Color-metallicity relations of GCs. X. M87 spec.
- Short Name:
- J/ApJS/256/29
- Date:
- 02 Mar 2022 00:28:26
- Publisher:
- CDS
- Description:
- We obtained spectra of some 140 globular clusters (GCs) associated with the Virgo central cD galaxy M87 with the Subaru/FOCAS MOS mode. The fundamental properties of GCs such as age, metallicity, and {alpha}-element abundance are investigated by using simple stellar population models. It is confirmed that the majority of M87 GCs are as old as, more metal-rich than, and more enhanced in {alpha}-elements than the Milky Way GCs. Our high-quality, homogeneous data set enables us to test the theoretical prediction of inflected color-metallicity relations (CMRs). The nonlinear-CMR hypothesis entails an alternative explanation for the widely observed GC color bimodality, in which even a unimodal metallicity spread yields a bimodal color distribution by virtue of nonlinear metallicity-to-color conversion. The newly derived CMRs of old, high-signal-to-noise-ratio GCs in M87 (the V-I CMR of 83 GCs and the M-T2 CMR of 78 GCs) corroborate the presence of the significant inflection. Furthermore, from a combined catalog with the previous study on M87 GC spectroscopy, we find that a total of 185 old GCs exhibit a broad, unimodal metallicity distribution. The results corroborate the nonlinear-CMR interpretation of the GC color bimodality, shedding further light on theories of galaxy formation.
3658. Color of Bright Galaxies
- ID:
- ivo://CDS.VizieR/J/AJ/109/543
- Title:
- Color of Bright Galaxies
- Short Name:
- J/AJ/109/543
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Total color indices (V-R)tot, (V-I)tot and effective color indices (V-R)eff, (V-I)eff in the Cousins VRI photometric system are presented for 501 mostly normal galaxies. The colors are computed using a procedure outlined in the Third Reference Catalogue of Bright Galaxies (RC3) whereby standard color curves approximated by Laplace-Gauss integrals are fitted to observed photoelectric multiaperture photometry. 11 sources of such photometry were used for our analysis, each source being assigned an appropriate weight according to a rigorous analysis of residuals of the data from the best-fitting standard color curves. Together with the integrated B-V and U-B colors provided in RC3, our analysis widens the range of wavelength of homogeneously defined colors of normal galaxies of all Hubble types. We present color-color and color-type relations that can be modeled to understand the star formation history of galaxies.
- ID:
- ivo://CDS.VizieR/J/PASP/121/1180
- Title:
- Color panorama image of the Milky Way
- Short Name:
- J/PASP/121/1180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This article describes the assembly of an optical (RGB) all-sky mosaic image with an image scale of 36"/pix, a limiting magnitude of approximately 14mag, and an 18 bit dynamic range. Using a portable low-cost CCD camera system, 70 fields (each covering 40{deg}x27{deg}) were imaged over a time span of 22 months from dark-sky locations in South Africa, Texas, and Michigan. The fields were photometrically calibrated against standard catalog stars. Using sky background data from the Pioneer 10 and 11 space probes, gradients resulting from artificial light pollution, airglow, and zodiacal light were eliminated, while the large-scale galactic and extragalactic background resulting from unresolved sources was preserved. The 648 megapixel image is a valuable educational tool, being able to fully utilize the resolution and dynamic range of modern full-dome planetarium projection systems.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A73
- Title:
- Color-period diagram for M48 (NGC2548)
- Short Name:
- J/A+A/583/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation periods are increasingly being used to derive ages for cool single field stars. Such ages are based on an empirical understanding of how cool stars spin down, acquired by constructing color-period diagrams (CPDs) for a series of open clusters. Our main aims here are to construct a CPD for M48, to compare this with other clusters of similar age to check for consistency, and to derive a rotational age for M48 using gyrochronology. We monitored M48 photometrically for over 2months with AIP's STELLA.I 1.2m telescope and the WiFSIP 4K imager in Tenerife. Light curves with 3mmag precision for bright (V~14mag) stars were produced and then analysed to provide rotation periods. A cluster CPD has then been constructed. We report 62 rotation periods for cool stars in M48. The CPD displays a clear slow/I-sequence of rotating stars, similar to those seen in the 625Myr-old Hyades and 590Myr-old Praesepe clusters, and below both, confirming that M48 is younger. A similar comparison with the 250Myr-old M34 cluster shows that M48 is older and does not possess any fast/C-sequence G or early K stars like those in M34, although relatively fast rotators do seem to be present among the late-K and M stars. A more detailed comparison of the CPD with rotational evolution models shows that the cluster stars have a mean age of 450Myr, and its (rotating) stars can be individually dated to +/-117Myr (26%). Much of this uncertainty stems from intrinsic astrophysical spread in initial periods, and almost all stars are consistent with a single age of 450Myr. The gyro-age of M48 as a whole is 450+/-50Myr, in agreement with the previously determined isochrone age of 400+/-100Myr.