- ID:
- ivo://CDS.VizieR/J/A+A/611/A76
- Title:
- DLAS dust-corrected metallicity
- Short Name:
- J/A+A/611/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Interpreting abundances of damped Ly-{alpha} absorbers (DLAs) from absorption-line spectroscopy has typically been a challenge because of the presence of dust. Nevertheless, because DLAs trace distant gas-rich galaxies regardless of their luminosity, they provide an attractive way of measuring the evolution of the metallicity of the neutral gas with cosmic time. This has been done extensively so far, but typically not taking proper dust corrections into account. The aims of this paper are to: (i) provide a simplified way of calculating dust corrections, based on a single observed [X/Fe], (ii) assess the importance of dust corrections for DLA metallicities and their evolution, and (iii) investigate the cosmic evolution of iron for a large DLA sample. We have derived dust corrections based on the observed [Zn/Fe], [Si/Fe], or [S/Fe], and confirmed their robustness. We present dust-corrected metallicities in a scale of [Fe/H]tot for 236 DLAs over a broad range of z, and assess the extent of dust corrections for different metals at different metallicities. Dust corrections in DLAs are important even for Zn (typically of 0.1-0.2, and up to 0.5dex), which is often neglected. Finally, we study the evolution of the dust-corrected metallicity with z. The DLA metallicities decrease with redshift, by a factor of 50-100 from today to ~12.6 billion years ago (z=5). When including dust corrections, the average DLA metallicities are 0.4-0.5dex higher than without corrections. The upper envelope of the relation between metallicity and z reaches solar metallicity at z<~0.5, although some systems can have solar metallicity already out to z~3.
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- ID:
- ivo://CDS.VizieR/J/AJ/157/78
- Title:
- Double & multiple star systems from GaiaDR2
- Short Name:
- J/AJ/157/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary and multiple stars have long provided an effective empirical method of testing stellar formation and evolution theories. In particular, the existence of wide binary systems (separations >20000 au) is particularly challenging to binary formation models as their physical separations are beyond the typical size of a collapsing cloud core (~5000-10000 au). We mined the recently published Gaia-DR2 catalog (Cat. I/345) to identify bright comoving systems in the five-dimensional space (sky position, parallax, and proper motion). We identified 3741 comoving binary and multiple stellar candidate systems, out of which 575 have compatible radial velocities for all the members of the system. The candidate systems have separations between ~400 and 500000 au. We used the analysis tools of the Virtual Observatory to characterize the comoving system members and to assess their reliability. The comparison with previous comoving systems catalogs obtained from TGAS showed that these catalogs contain a large number of false systems. In addition, we were not able to confirm the ultra-wide binary population presented in these catalogs. The robustness of our methodology is demonstrated by the identification of well known comoving star clusters and by the low contamination rate for comoving binary systems with projected physical separations <50000 au. These last constitute a reliable sample for further studies. The catalog is available online at the Spanish Virtual Observatory portal (http://svo2.cab.inta-csic.es/vocats/v2/comovingGaiaDR2/).
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/1412
- Title:
- Dust and SSP-stellar parameters of M82
- Short Name:
- J/MNRAS/452/1412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use near ultraviolet and optical photometry to investigate the dust properties in the nearby starburst galaxy M82. By combining imaging from the Swift/UVOT instrument and optical data from the Sloan Digital Sky Survey, we derive the extinction curve parametrized by the standard R_V_ factor, and the strength of the NUV 2175 {AA} feature - quantified by a parameter B - out to projected galactocentric distances of 4 kpc. Our analysis is robust against possible degeneracies from the properties of the underlying stellar populations. Both B and R_V_ correlate with galactocentric distance, revealing a systematic trend of the dust properties. Our results confirm previous findings that dust in M82 is better fitted by a Milky Way standard extinction curve, in contrast to a Calzetti law. We find a strong correlation between R_V_ and B, towards a stronger NUV bump in regions with higher R_V_, possibly reflecting a distribution with larger dust grain sizes. The data we use were taken before SN2014J, and therefore can be used to probe the properties of the interstellar medium before the event. Our R_V_ values around the position of the supernova are significantly higher than recent measurements post-SN2014J (R_V_~1.4). This result is consistent with a significant change in the dust properties after the supernova event, either from disruption of large grains or from the contribution by an intrinsic circumstellar component. Intrinsic variations among supernovae not accounted for could also give rise to this mismatch.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A78
- Title:
- Dust extinction map of the Nessie filament
- Short Name:
- J/A+A/616/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An increasing number of hundred-parsec scale, high line-mass filaments have been detected in the Galaxy. Their evolutionary path, including fragmentation towards star formation, is virtually unknown. We characterize the fragmentation within the Nessie filament, covering size-scales between 0.1-100pc. We also connect the small-scale fragments to the star-forming potential of the cloud. We combine near-infrared data from the VVV survey with mid-infrared GLIMPSE data to derive a high-resolution dust extinction map and apply a wavelet decomposition technique on it to analyze the fragmentation characteristics of the cloud, which are compared with predictions from fragmentation models. We compare the detected objects to those identified in 10 times coarser resolution from ATLASGAL data. We present a high-resolution extinction map of Nessie. We estimate the mean line-mass of Nessie to be 627M_{sun}_/pc and the distance to be 3.5kpc. We find that Nessie shows fragmentation at multiple size scales. The nearest-neighbour separations of the fragments at all scales are within a factor of 2 of the Jeans' length at that scale. However, the relationship between the mean densities of the fragments and their separations is significantly shallower than expected for Jeans' fragmentation. The relationship is similar to the one predicted for a filament that exhibits a Larson-like scaling between size-scale and velocity dispersion; such a scaling may result from turbulent support. Based on the number of YSOs in Nessie, we estimate that the star formation rate is 371M_{sun}_/Myr; similar values result if using the number of dense cores, or the amount of dense gas, as the proxy of star formation. The star formation efficiency is 0.017. These numbers indicate that Nessie's star-forming content is comparable to the Solar neighborhood giant molecular clouds like Orion A.
- ID:
- ivo://CDS.VizieR/J/ApJ/711/1236
- Title:
- Equivalent width of H_2_ from FUSE
- Short Name:
- J/ApJ/711/1236
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Far Ultraviolet Spectroscopic Explorer (FUSE) has allowed precise determinations of the column densities of molecular hydrogen (H_2_) in Galactic lines of sight with a wide range of pathlengths and extinction properties. However, survey studies of lines of sight with greater extinction have been mostly restricted to the low-J states (lower total angular momentum) in which most molecular hydrogen is observed. This paper presents a survey of column densities for the molecular hydrogen in states of greater rotational excitation (J>=2) in Galactic lines of sight with log N(H_2_)>~20. This study is comprehensive through the highest excited state detectable in each line of sight. J=5 is observed in every line of sight, and we detect J=7 in four lines of sight, J=8 in one line of sight, and vibrationally excited H_2_ in two lines of sight.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/23
- Title:
- E(V-I) reddening map of MCs from OGLE-IV RC stars
- Short Name:
- J/ApJS/252/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most extensive and detailed reddening maps of the Magellanic Clouds (MCs) derived from the color properties of Red Clump (RC) stars. The analysis is based on the deep photometric maps from the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV), covering approximately 670deg^2^ of the sky in the Magellanic System region. The resulting maps provide reddening information for 180deg^2^ in the Large Magellanic Cloud (LMC) and 75deg^2^ in the Small Magellanic Cloud (SMC), with a resolution of 1.7'x1.7' in the central parts of the MCs, decreasing to approximately 27'x27' in the outskirts. The mean reddening is E(V-I)=0.100+/-0.043mag in the LMC and E(V-I)=0.047+/-0.025mag in the SMC. We refine methods of calculating the RC color to obtain the highest possible accuracy of reddening maps based on RC stars. Using spectroscopy of red giants, we find the metallicity gradient in both MCs, which causes a slight decrease of the intrinsic RC color with distance from the galaxy center of ~0.002mag/deg in the LMC and between 0.003 and 0.009mag/deg in the SMC. The central values of the intrinsic RC color are 0.886 and 0.877mag in the LMC and SMC, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A94
- Title:
- Exoplanetary parameters for 18 bright stars
- Short Name:
- J/A+A/586/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the interferometric angular diameters of 18 bright stars: HD3651 , HD9826, HD19994, HD75732, HD167042, HD170693, HD173416, HD185395, HD190360, HD217014, HD221345, HD1367, HD1671, HD154633, HD161178, HD161151, HD209369, HD218560. The first 11 host exoplanets (except HD185395). We combined these angular diameters {theta}_LD_ with the stellar distances to estimate the stellar radii. We perform SED fitting of the photometry to derive the stars bolometric flux Fbol with and without stellar extinction Av. We then give the effective temperature Teff_SED_ and angular diameter {theta}_SED_ from this SED fit, considering fixed Av, metallicity [Fe/H] and gravity log(g). Then, taking into account the stellar extinction, we derived from the bolometric flux and the measured angular diameters the effective temperature and luminosity to place the stars on the H-R diagram. We then used the PARSEC models to derive the best fit ages and masses of the stars, with error bars derived from Monte Carlo calculations. Typically, for main sequence stars, two distinct sets of solutions appear (an old and a young age). For stars that host known exoplanets, we also derive the exoplanets parameters considering the two different solutions (old and young): semi-major axis, planetary minimum mass and habitable zone of the host stars. Finally, we give the true mass, radius and density of the transiting exoplanet 55 Cnc e using the inteferometric radius and photometry.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/11
- Title:
- Exploring 6 AGN dusty torus models. II.
- Short Name:
- J/ApJ/884/11
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers devoted to exploring a set of six dusty models of active galactic nuclei (AGN) with available spectral energy distributions. These models are the smooth torus by Fritz+ (2006MNRAS.366..767F), the clumpy torus by Nenkova+ (2008ApJ...685..147N and 2008ApJ...685..160N), the clumpy torus by Honig & Kishimoto (2010A&A...523A..27H), the two-phase torus by Siebenmorgen+ (2015A&A...583A.120S), the two-phase torus by Stalevski+ (2012MNRAS.420.2756S and 2016MNRAS.458.2288S), and the wind model by Honig & Kishimoto (2017ApJ...838L..20H). The first paper explores discrimination among models and the parameter restriction using synthetic spectra. Here we perform spectral fitting of a sample of 110 AGN drawn from the Swift/BAT survey with Spitzer/IRS spectroscopic data. The aim is to explore which is the model that describes better the data and the resulting parameters. The clumpy wind-disk model by Honig & Kishimoto provides good fits for ~50% of the sample, and the clumpy torus model by Nenkova+ is good at describing ~30% of the objects. The wind-disk model by Honig & Kishimoto is better for reproducing the mid-infrared spectra of type 1 Seyferts (with 60% of the type 1 Seyferts well reproduced by this model compared to the 10% well represented by the clumpy torus model by Nenkova+), while type 2 Seyferts are equally fitted by both models (roughly 40% of the type 2 Seyferts). Large residuals are found irrespective of the model used, indicating that the AGN dust continuum emission is more complex than predicted by the models or that the parameter space is not well sampled. We found that all the resulting parameters for our AGN sample are roughly constrained to 10%-20% of the parameter space. Contrary to what is generally assumed, the derived outer radius of the torus is smaller (reaching up to a factor of ~5 smaller for 10pc tori) for the smooth torus by Fritz+ and the two-phase torus by Stalevski+ than the one derived from the clumpy torus by Nenkova+ Covering factors and line-of-sight viewing angles strongly depend on the model used. The total dust mass is the most robust derived quantity, giving equivalent results for four of these models.
- ID:
- ivo://CDS.VizieR/J/BaltA/11/231
- Title:
- Extinction in MBM12
- Short Name:
- J/BaltA/11/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric magnitudes and color indices in the Vilnius seven-color system for 152 stars are used to investigate the interstellar extinction in the area of the Aries molecular cloud MBM 12, coinciding with the L1454 and L1457 dust clouds. Spectral types, absolute magnitudes, color excesses, interstellar extinctions and distances of the stars are determined. The plot of interstellar extinction A_v_ versus distance shows that the dust cloud is situated at a distance of 325pc, at 180pc from the Galactic plane, and its true diameter is about 11pc. The interstellar extinction law in the area is found to be normal, typical for the diffuse dust. Ten peculiar or unresolved binary stars and some heavily reddened stars are detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/L81
- Title:
- Extinction in star-forming regions
- Short Name:
- J/ApJ/693/L81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Spitzer Infrared Spectrograph observations of G0-M4III stars behind dark clouds, I construct 5-20um empirical extinction curves for 0.3<=A_K_<7, which is equivalent to A_V_ between ~3 and 50. For A_K_<1, the curve appears similar to the Mathis diffuse interstellar medium extinction curve, but with a greater degree of extinction. For A_K_>1, the curve exhibits lower contrast between the silicate and absorption continuum, develops ice absorption, and lies closer to the Weingartner and Draine R_V_=5.5 Case B curve, a result which is consistent with that of Flaherty et al. (2007ApJ...663.1069F) and Chiar et al. (2007ApJ...666L..73C). Recently, work using Spitzer Infrared Array Camera data by Chapman et al. independently reaches a similar conclusion that the shape of the extinction curve changes as a function of increasing A_K_. By calculating the optical depths of the 9.7um silicate and 6.0, 6.8, and 15.2um ice features, I determine that a process involving ice is responsible for the changing shape of the extinction curve and speculate that this process is a coagulation of ice-mantled grains rather than ice-mantled grains alone.
