- ID:
- ivo://CDS.VizieR/J/ApJ/775/129
- Title:
- gri photometry in compact groups of galaxies
- Short Name:
- J/ApJ/775/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact groups of galaxies provide conditions similar to those experienced by galaxies in the earlier universe. Recent work on compact groups has led to the discovery of a dearth of mid-infrared transition galaxies (MIRTGs) in Infrared Array Camera (3.6-8.0{mu}m) color space as well as at intermediate specific star formation rates. However, we find that in compact groups these MIRTGs have already transitioned to the optical ([g-r]) red sequence. We investigate the optical color-magnitude diagram (CMD) of 99 compact groups containing 348 galaxies and compare the optical CMD with mid-infrared (mid-IR) color space for compact group galaxies. Utilizing redshifts available from Sloan Digital Sky Survey, we identified new galaxy members for four groups. By combining optical and mid-IR data, we obtain information on both the dust and the stellar populations in compact group galaxies. We also compare with more isolated galaxies and galaxies in the Coma Cluster, which reveals that, similar to clusters, compact groups are dominated by optically red galaxies. While we find that compact group transition galaxies lie on the optical red sequence, LVL+SINGS mid-IR transition galaxies span the range of optical colors. The dearth of mid-IR transition galaxies in compact groups may be due to a lack of moderately star-forming low mass galaxies; the relative lack of these galaxies could be due to their relatively small gravitational potential wells. This makes them more susceptible to this dynamic environment, thus causing them to more easily lose gas or be accreted by larger members.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/1405
- Title:
- griz and CT1 photometry in M87
- Short Name:
- J/MNRAS/431/1405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Gemini griz' photometry for 521 globular cluster (GC) candidates in a 5.5x5.5arcmin^2^ field centred 3.8-arcmin to the south and 0.9-arcmin to the west of the centre of the giant elliptical galaxy NGC 4486. All these objects have previously published (C-T1) photometry. We also present new (C-T1) photometry for 338 globulars, within 1.7-arcmin in galactocentric radius, which have (g-z) colours in the photometric system adopted by the Virgo Cluster Survey of the Advanced Camera for Surveys of the Hubble Space Telescope (HST). These photometric data are used to define a self-consistent multicolour grid (avoiding polynomial fits) and preliminarily calibrated in terms of two chemical abundance scales. The resulting multicolour colour-chemical abundance relations are used to test GC chemical abundance distributions. This is accomplished by modelling the 10 GC colour histograms that can be defined in terms of the Cgriz' bands. Our results suggest that the best fit to the GC observed colour histograms is consistent with a genuinely bimodal chemical abundance distribution N_GC_(Z). On the other side, each ('blue' and 'red') GC subpopulation follows a distinct colour-colour relation.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A39
- Title:
- g'r'i'z'JHKs light curves of GRB 081029
- Short Name:
- J/A+A/531/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- GROND multi-colour follow-up of GRB 081029 is used to study the nature of the late-time extremely fast rebrightening that appears in the optical-NIR light-curve of the afterglow of GRB 081029.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/L4
- Title:
- GV galaxies UV-optical radial color profiles
- Short Name:
- J/ApJ/792/L4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Letter, we analyze the radial ultraviolet-optical color distributions in a sample of low redshift green valley galaxies, with the Galaxy Evolution Explorer (GALEX)+Sloan Digital Sky Survey (SDSS) images, to investigate how the residual recent star formation is distributed in these galaxies. We find that the dust-corrected u-r colors of early-type galaxies (ETGs) are flat out to R_90_, while the colors monotonously turn blue when r>0.5 R_50_ for late-type galaxies (LTGs). More than half of the ETGs are blue-cored and have remarkable positive NUV-r color gradients, suggesting that their star formations are centrally concentrated. The rest have flat color distributions out to R_90_. The centrally concentrated star formation activity in a large portion of ETGs is confirmed by the SDSS spectroscopy, showing that ~50% of the ETGs have EW(H{alpha})>6.0 {AA}. Of the LTGs, 95% show uniform radial color profiles, which can be interpreted as a red bulge plus an extended blue disk. The links between the two kinds of ETGs, e.g., those objects having remarkable "blue-cores" and those having flat color gradients, are less known and require future investigations. It is suggested that the LTGs follow a general model by which quenching first occurs in the core regions, and then finally extend to the rest of the galaxy. Our results can be re-examined and have important implications for the IFU surveys, such as MaNGA and SAMI.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A28
- Title:
- Halo metal-poor stars chemical data
- Short Name:
- J/A+A/593/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an analysis of 107 extremely metal-poor (EMP) stars with metallicities lower than [Fe/H]=-3.0, identified in medium-resolution spectra in the Sloan Digital Sky Survey (SDSS). Our analysis provides estimates of the stellar effective temperatures and surface gravities, as well as iron, calcium, and magnesium abundances. We followed the same method as in previous papers of this series. The method is based on comparisons of the observed spectra with synthetic spectra. The abundances of Fe, Ca, and Mg were determined by fitting spectral regions that are dominated by lines of each element. In addition, we present a technique to determine upper limits for elements whose features are not detected in a given spectrum. We also analyzed our sample with the SEGUE stellar parameter pipeline to obtain additional determinations of the atmospheric parameters and iron and alpha-element abundances, which we then compare with ours. In addition, we used these parameters to infer [C/Fe] ratios. Ca is typically the only element in these spectra with a moderate to low signal-to-noise ratio and medium resolution in this metallicity regime with lines that are sufficiently strong to reliably measure its abundance. Fe and Mg exhibit weaker features that in most cases only provide upper limits. We measured [Ca/Fe] and [Mg/Fe] for EMP stars in the SDSS spectra and conclude that most of the stars exhibit the typical enhancement level for alpha-elements, ~+0.4, although some stars for which only [Fe/H] upper limits could be estimated indicate higher [alpha/Fe] ratios. We also find that 26% of the stars in our sample can be classified as carbon-enhanced metal-poor (CEMP) stars and that the frequency of CEMP stars also increases with decreasing metallicity, as has been reported for previous samples. We identify a rare, bright (g=11.90) EMP star, SDSS J134144.61+474128.6, with [Fe/H]=-3.27, [C/Fe]=+0.95, and elevated magnesium ([Mg/Fe]=+0.62), an abundance pattern typical of CEMP-no stars.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A136
- Title:
- Halo red giants from the SEGUE survey
- Short Name:
- J/A+A/534/A136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic search for halo field stars that originally formed in globular clusters. Using moderate-resolution SDSS-III/SEGUE-2 spectra of 561 red giants with typical halo metallicities (-1.8<=[Fe/H]<=-1.0), we identify 16 stars, 3% of the sample, with CN and CH bandstrength behavior indicating depleted carbon and enhanced nitrogen abundances relative to the rest of the data set. Since globular clusters are the only environment known in which stars form with this pattern of atypical light-element abundances, we claim that these stars are second-generation globular cluster stars that have been lost to the halo field via normal cluster mass-loss processes.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/865
- Title:
- Halo streams in the SDSS-DR7
- Short Name:
- J/ApJ/698/865
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected stellar halo streams in the solar neighborhood using data from the seventh public data release of the Sloan Digital Sky Survey (SDSS), which includes the directed stellar program Sloan Extension For Galactic Understanding and Exploration (SEGUE). In order to derive distances to each star, we used the metallicity-dependent photometric parallax relation from Ivezic et al. (2008ApJ...684..287I). Our final sample consists of 22321 nearby (d<=2kpc), metal-poor ([Fe/H]<=-0.5) main-sequence stars with six-dimensional estimates of position and space velocity (r{vec},{nu}{vec}). We characterize the orbits of these stars through suitable kinematic proxies for their "effective" integrals of motion, angular momentum, eccentricity, and orbital polar angle and compare the observed distribution to expectations from a smooth distribution in four [Fe/H] bins. The metallicities provide an additional dimension in parameter space that is well suited to distinguish tidal streams from those of dynamical origin. On this basis, we identify at least five significant "phase-space overdensities" of stars on very similar orbits in the solar neighborhood to which we can assign unambiguously peaked [Fe/H] distributions. Three of them have been identified previously, including the halo stream discovered by Helmi et al. (1999MNRAS.307..495H) at a significance level of {sigma}=12.0. In addition, we find at least two new genuine halo streams, judged by their kinematics and [Fe/H], at {sigma}=2.9 and 4.8, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/128
- Title:
- H{alpha} emitting galaxies in COSMOS-2 field
- Short Name:
- J/ApJS/175/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To derive a new H{alpha} luminosity function and to understand the clustering properties of star-forming galaxies at z~0.24, we have made a narrowband imaging survey for H{alpha}-emitting galaxies in the Hubble Space Telescope (HST) COSMOS 2 square degree field. We used the narrowband filter NB816 ({lambda}_c_=8150{AA}, {Delta}{lambda}=120{AA}) and sampled H{alpha} emitters with EW_obs_(H{alpha}+[NII])>12{AA} in a redshift range between z=0.233 and 0.251 corresponding to a depth of 70Mpc. We obtained 980 H{alpha}-emitting galaxies in a sky area of 5540arcmin^2^, corresponding to a survey volume of 3.1x10^4^Mpc^3^.
- ID:
- ivo://CDS.VizieR/J/ApJS/242/11
- Title:
- H{alpha} imaging survey of the 40% ALFALFA HI LSBGs
- Short Name:
- J/ApJS/242/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a narrow H{alpha}-band imaging survey of 357 low surface brightness galaxies (LSBGs) that are selected from the spring sky region of the 40% Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI Survey. All the H{alpha} images are obtained from the 2.16m telescope, operated by the Xinglong Observatory of the National Astronomical Observatories, Chinese Academy of Sciences. We provide the H{alpha} fluxes and derive the global star formation rates (SFRs) of LSBGs after the Galactic extinction, internal extinction, and [NII] contamination correction. Compared to normal star-forming galaxies, LSBGs have a similar distribution in the HI surface density ({Sigma}HI), but their SFRs and star formation surface density ({Sigma}SFR) are much lower. Our results show that the gas-rich LSBGs selected from the ALFALFA survey obviously deviate from the Kennicutt-Schmidt law, in the relation between the star formation surface density ({Sigma}SFR) and the gas surface density ({Sigma}gas). However, they follow the extended Schmidt law well when taking the stellar mass of the galaxy into consideration.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A16
- Title:
- H{alpha}3 V. Coma cluster
- Short Name:
- J/A+A/576/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Neutral hydrogen represents the major observable baryonic constituent of galaxies that fuels the formation of stars through transformation of molecular hydrogen. The emission of the hydrogen recombination line H{alpha} is the most direct tracer of the process that transforms gas (fuel) into stars. We continue to present H{alpha}3 (acronym for H{alpha}-{alpha}{alpha}), an extensive H{alpha}+[NII] narrow-band imaging campaign of galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA), using the instrumentation available at the San Pedro Martir (SPM) observatory (Mexico). In 48 nights since 2011 we were able to carry out the H{alpha} imaging observations of 724 galaxies in the region of the Coma supercluster 10h<RA<16h ; 24{deg}<Dec<28{deg} and 3900<cz<9000km/s. Of these, 603 are selected from the ALFALFA and constitute a 97% complete sample. They provide for the first time a complete census of the massive star formation properties of local gas-rich galaxies belonging to different environments (cluster vs. filaments), morphological types (spirals vs. dwarf Irr), over a wide range of stellar mass (~10^8^-10^11.5^M_{sun}_) in the Coma supercluster. The present Paper V provides H{alpha} data and derived star formation rates for the observed galaxies.
