- ID:
- ivo://CDS.VizieR/J/PAZh/38/15
- Title:
- Total-to-selective extinction ratio within 700pc
- Short Name:
- J/PAZh/38/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multicolor photometry from the Tycho-2 and 2MASS catalogues for 11990 OB (2008AstL...34....7G; 2012AstL...38..694G) and 30671 K-type red giant branch stars (2011AstL...37..707G) is used to detect systematic large-scale variations of the interstellar extinction law within the nearest kiloparsec. The characteristic of the extinction law, the total-to-selective extinction ratio Rv, which also characterizes the size and other properties of interstellar dust grains, has been calculated for various regions of space by the extinction law extrapolation method. The results for the two classes of stars agree: the standard deviation of the "red giants minus OB" Rv differences within 500pc of the Sun is 0.2. The detected Rv variations between 2.2 and 4.4 not only manifest themselves in individual clouds but also span the entire space near the Sun, following Galactic structures. In the Local Bubble within about 100 pc of the Sun, Rv has a minimum. In the inner part of the Gould Belt and at high Galactic latitudes, at a distance of about 150 pc from the Sun, Rv reaches a maximum and then decreases to its minimum in the outer part of the Belt and other directions at a distance of about 500 pc from the Sun, returning to its mean values far from the Sun. The detected maximum of Rv at high Galactic latitudes is important when allowance is made for the interstellar extinction toward extragalactic objects. In addition, a monotonic increase in Rv by 0.3 per kpc toward the Galactic center has been found near the Galactic equator. It is consistent with the result obtained by Zasowski et al. (2009ApJ...707..510Z) for much of the Galaxy. Ignoring the Rv variations and traditionally using a single value for the entire space must lead to systematic errors in the calculated distances reaching 10%.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/157/212
- Title:
- Ultra-diffuse galaxies at ultraviolet wavelengths
- Short Name:
- J/AJ/157/212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure near-ultraviolet (NUV) aperture magnitudes from Galaxy Evolution Explorer images for 258 ultra-diffuse galaxy (UDG) candidates drawn from the initial Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes) survey of ~300 square degrees surrounding, and including, the Coma galaxy cluster. For the vast majority, 242 of them, we present flux upper limits due either to a lack of significant flux in the aperture or confusion with other objects projected within the aperture. These limits often place interesting constraints on the UDG candidates, indicating that they are non-star-forming or quiescent. In particular, we identify field, quiescent UDG candidates, which are a challenge for formation models and are, therefore, compelling prospects for spectroscopic follow-up and distance determinations. We present far-ultraviolet (FUV) and NUV magnitudes for 16 detected UDG candidates and compare those galaxies to the local population of galaxies on color-magnitude and specific star formation rate diagrams. The NUV-detected UDG candidates form mostly an extension toward lower stellar masses of the star-forming galaxy sequence, and none of these lie within regions of high local galaxy density. UDG candidates span a range of properties, although almost all are consistent with being quiescent, low surface brightness galaxies, regardless of environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/153
- Title:
- Ultraviolet Extinction in the GALEX Bands. UVEXT
- Short Name:
- J/ApJ/861/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interstellar extinction in ultraviolet is the most severe in comparison with optical and infrared wavebands and a precise determination plays an important role in correctly recovering the ultraviolet brightness and colors of objects. By finding the observed bluest colors at the given effective temperature and metallicity range of dwarf stars, stellar intrinsic colors, C_B,V_^0^, C_NUV,B_^0^, C_FUV,B_^0^, and C_FUV,NUV_^0^, are derived according to the stellar parameters from the LAMOST spectroscopic survey and photometric results from the GALEX and APASS surveys. With the derived intrinsic colors, the ultraviolet color excesses are calculated for about 25,000 A- and F-type dwarf stars. Analysis of the color excess ratios yields the extinction law related to the GALEX UV bands: E_NUV,B_/E_B,V_=3.77, E_FUV,B_/E_B,V_=3.39, and E_FUV,NUV_/E_B,V_=-0.38. The results agree very well with previous works in the NUV band and in general with the extinction curve derived by Fitzpatrick (1999PASP..111...63F) for R_V_=3.35.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/34
- Title:
- 24um excesses in clusters & membership of NGC2244
- Short Name:
- J/ApJ/836/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterize the first 40 Myr of evolution of circumstellar disks through a unified study of the infrared properties of members of young clusters and associations with ages from 2Myr up to ~40Myr: NGC1333, NGC1960, NGC2232, NGC2244, NGC2362, NGC2547, IC348, IC2395, IC4665, ChamaeleonI, OrionOB1a and OB1b, Taurus, the {beta} Pictoris Moving Group, {rho} Ophiuchi, and the associations of Argus, Carina, Columba, Scorpius-Centaurus, and Tucana-Horologium. Our work features: (1) a filtering technique to flag noisy backgrounds; (2) a method based on the probability distribution of deflections, P(D), to obtain statistically valid photometry for faint sources; and (3) use of the evolutionary trend of transitional disks to constrain the overall behavior of bright disks. We find that the fraction of disks three or more times brighter than the stellar photospheres at 24{mu}m decays relatively slowly initially and then much more rapidly by ~10Myr. However, there is a continuing component until ~35Myr, probably due primarily to massive clouds of debris generated in giant impacts during the oligarchic/chaotic growth phases of terrestrial planets. If the contribution from primordial disks is excluded, the evolution of the incidence of these oligarchic/chaotic debris disks can be described empirically by a log-normal function with the peak at 12-20Myr, including ~13% of the original population, and with a post-peak mean duration of 10-20Myr.
- ID:
- ivo://CDS.VizieR/J/AJ/145/101
- Title:
- Updated nearby galaxy catalog
- Short Name:
- J/AJ/145/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an all-sky catalog of 869 nearby galaxies having individual distance estimates within 11Mpc or corrected radial velocities V_LG_<600km/s. The catalog is a renewed and expanded version of the Catalog of Neighboring Galaxies by Karachentsev et al (2004, cat. J/AJ/127/2031). It collects data on the following galaxy observables: angular diameters, apparent magnitudes in far-UV, B, and K_s_bands, H{alpha} and HI fluxes, morphological types, HI-line widths, radial velocities, and distance estimates. In this Local Volume (LV) sample, 108 dwarf galaxies still remain without measured radial velocities. The catalog yields also calculated global galaxy parameters: linear Holmberg diameter, absolute B magnitude, surface brightness, HI mass, stellar mass estimated via K-band luminosity, HI rotational velocity corrected for galaxy inclination, indicative mass within the Holmberg radius, and three kinds of "tidal index," which quantify the local density environment. The catalog is supplemented with data based on the local galaxies, which presents their optical and available H{alpha} images, as well as other services. We briefly discuss the Hubble flow within the LV and different scaling relations that characterize galaxy structure and global star formation in them. We also trace the behavior of the mean stellar mass density, HI-mass density, and star formation rate density within the volume considered.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/16
- Title:
- UV emission of stars in LAMOST. I. Catalogs
- Short Name:
- J/ApJS/235/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the ultraviolet magnitudes for over three million stars in the LAMOST survey, in which 2,202,116 stars are detected by GALEX. For 889,235 undetected stars, we develop a method to estimate their upper limit magnitudes. The distribution of (FUV-NUV) shows that the color declines with increasing effective temperature for stars hotter than 7000K in our sample, while the trend disappears for the cooler stars due to upper atmosphere emission from the regions higher than their photospheres. For stars with valid stellar parameters, we calculate the UV excesses with synthetic model spectra, and find that the (FUV - NUV) versus R'_FUV_ can be fitted with a linear relation and late-type dwarfs tend to have high UV excesses. There are 87,178 and 1,498,103 stars detected more than once in the visit exposures of GALEX in the FUV and NUV, respectively. We make use of the quantified photometric errors to determine statistical properties of the UV variation, including intrinsic variability and the structure function on the timescale of days. The overall occurrence of possible false positives is below 1.3% in our sample. UV absolute magnitudes are calculated for stars with valid parallaxes, which could serve as a possible reference frame in the NUV. We conclude that the colors related to UV provide good criteria to distinguish between M giants and M dwarfs, and the variability of RR Lyrae stars in our sample is stronger than that of other A and F stars.
- ID:
- ivo://CDS.VizieR/II/114
- Title:
- UV Interstellar Extinction
- Short Name:
- II/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The documentation is mostly adapted from the "Documentation for the Machine-Readable Version of A catalog of Ultraviolet Interstellar Extinction Excesses for 1415 Stars" by Wayne H. Warren Jr., May 1986, National Space Science Data Center NSSDC/WDC-A-R&S 86-05 This document describes the machine-readable version of the catalog as it is currently being distributed from the Astronomical Data Centers. It is intended to enable users to read and process the data without problems and guesswork, but it is not intended to replace the original published paper, which users should study before processing the data. The format described below is very similar to that given on page 431 of the source reference, but some modifications were made at the ADC (with the consent of the authors) to effect uniformity.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/40
- Title:
- Variable stars in M31 and M33. V. HR diagram
- Short Name:
- J/ApJ/844/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HR diagrams for the massive star populations in M31 and M33, including several different types of emission-line stars: the confirmed luminous blue variables (LBVs), candidate LBVs, B[e] supergiants, and the warm hypergiants. We estimate their apparent temperatures and luminosities for comparison with their respective massive star populations and evaluate the possible relationships of these different classes of evolved, massive stars, and their evolutionary state. Several of the LBV candidates lie near the LBV/S Dor instability strip that supports their classification. Most of the B[e] supergiants, however, are less luminous than the LBVs. Many are very dusty with the infrared flux contributing one-third or more to their total flux. They are also relatively isolated from other luminous OB stars. Overall, their spatial distribution suggests a more evolved state. Some may be post-RSGs (red supergiants) like the warm hypergiants, and there may be more than one path to becoming a B[e] star. There are sufficient differences in the spectra, luminosities, spatial distribution, and the presence or lack of dust between the LBVs and B[e] supergiants to conclude that one group does not evolve into the other.
- ID:
- ivo://CDS.VizieR/J/ApJ/825/50
- Title:
- Variable stars in M31 & M33. III. YSGs & RSGs
- Short Name:
- J/ApJ/825/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent supernova (SN) and transient surveys have revealed an increasing number of non-terminal stellar eruptions. Though the progenitor class of these eruptions includes the most luminous stars, little is known of the pre-SN mechanics of massive stars in their most evolved state, thus motivating a census of possible progenitors. From surveys of evolved and unstable luminous star populations in nearby galaxies, we select a sample of yellow and red supergiant (RSG) candidates in M31 and M33 for review of their spectral characteristics and spectral energy distributions (SEDs). Since the position of intermediate- and late-type supergiants on the color-magnitude diagram can be heavily contaminated by foreground dwarfs, we employ spectral classification and multi-band photometry from optical and near-infrared surveys to confirm membership. Based on spectroscopic evidence for mass loss and the presence of circumstellar (CS) dust in their SEDs, we find that 30%-40% of the yellow supergiants are likely in a post-RSG state. Comparison with evolutionary tracks shows that these mass-losing, post-RSGs have initial masses between 20 and 40M_{sun}_. More than half of the observed RSGs in M31 and M33 are producing dusty CS ejecta. We also identify two new warm hypergiants in M31, J004621.05+421308.06 and J004051.59+403303.00, both of which are likely in a post-RSG state.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/89
- Title:
- Variation of mid-IR extinction
- Short Name:
- J/ApJ/707/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the data obtained from the Spitzer/Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIPMSE) Legacy Program and the Two Micron All Sky Survey (2MASS) project, we derive the extinction in the four IRAC bands, [3.6], [4.5], [5.8], and [8.0]um, relative to the 2MASS Ks band (at 2.16um) for 131 GLIPMSE fields along the Galactic plane within |l|<=65{deg}, using red giants and red clump giants as tracers. As a whole, the mean extinction in the IRAC bands (normalized to the 2MASS Ks band), A_[3.6]_/A_Ks_~0.63+/-0.01, A_[4.5]_/A_Ks_~0.57+/-0.03, A_[5.8]/A_Ks_~0.49+/-0.03, A_[8.0]_/A_Ks_~0.55+/-0.03, exhibits little variation with wavelength (i.e., the extinction is somewhat flat or gray). As far as individual sightline is concerned, however, the wavelength dependence of the mid-infrared interstellar extinction A_{lambda}_/A_Ks_ varies from one sightline to another, suggesting that there may not exist a "universal" IR extinction law.
