In this paper we present and analyze new CCD UBVRI photometry down to V~21 in the region of the young open cluster Collinder 232, located in the Carina spiral arm, and discuss its relationship to Trumpler 14 and Trumpler 16, the two most prominent young open clusters located in the core of NGC 3372 (the Carina Nebula).
This is the first paper of a series devoted to the {lambda} Orionis star-forming region, Orion's Head, from the X-ray perspective. Our final aim is to provide a comprehensive view of this complex region, which includes several distinct associations and dark clouds. We aim to uncover the population of the central, young star cluster Collinder 69, and in particular those diskless Class III objects not identified by previous surveys based on near- and mid-infrared searches, and to establish the X-ray luminosity function for the association.
In order to understand the past merging history of elliptical galaxies, we studied the optical-near-infrared (NIR) color gradients of 204 elliptical galaxies. These galaxies are selected from the overlap region of the Sloan Digital Sky Survey (SDSS) Stripe 82 and the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The use of optical and NIR data (g, r, and K) provides large wavelength baselines, and breaks the age-metallicity degeneracy, allowing us to derive age and metallicity gradients. The use of the deep SDSS Stripe 82 images makes it possible for us to examine how the color/age/metallicity gradients are related to merging features. We find that the optical-NIR color and the age/metallicity gradients of elliptical galaxies with tidal features are consistent with those of relaxed ellipticals, suggesting that the two populations underwent a similar merging history on average and that mixing of stars was more or less completed before the tidal features disappeared. Elliptical galaxies with dust features have steeper color gradients than the other two types, even after masking out dust features during the analysis, which can be due to a process involving wet merging. More importantly, we find that the scatter in the color/age/metallicity gradients of the relaxed and merging feature types decreases as their luminosities (or masses) increase at M>10^11.4^M_{sun}_ but stays large at lower luminosities. Mean metallicity gradients appear nearly constant over the explored mass range, but a possible flattening is observed at the massive end.
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.
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.
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.
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.
The catalogue contains observations of essentially all stars brighter than fifth visual magnitude north of declination -20 degrees and brighter than fourth visual magnitude south of declination -20 degrees, in the 13-color medium-narrow-band photometric system.
We present a sample of 484 L dwarfs, 210 of which are newly discovered from the Sloan Digital Sky Survey (SDSS) Data Release 7 spectroscopic database. We combine this sample with known L dwarfs to investigate their izJHKS colors. We present photometric distance relations based on i-z and i-J colors and derive distances to our L dwarf sample. We combine the distances with SDSS/2MASS proper motions in order to examine the tangential velocities.
We present a compilation of all available colors for 104 Minor Bodies in the Outer Solar System (MBOSSes); for each object, the original references are listed. The measurements were combined in a way that does not introduce rotational color artifacts. We then derive the slope, or reddening gradient, of the low resolution reflectance spectra obtained from the broad-band color for each object. A set of color-color diagrams, histograms and cumulative probability functions are presented as a reference for further studies, and are discussed.
