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- ID:
- ivo://CDS.VizieR/J/ApJ/613/312
- Title:
- Synthetic Lick indices of alpha-enhanced stars
- Short Name:
- J/ApJ/613/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of 402 F, G, and K solar neighborhood stars, with accurate estimates of [Fe/H] in the range -1.0 to +0.5dex, aimed at the detection of {alpha}-enhanced stars and at the investigation of their kinematical properties. The analysis is based on the comparison of 571 sets of spectral indices in the Lick/IDS system, coming from four different observational data sets, with synthetic indices computed with solar-scaled abundances and with {alpha}-element enhancement. We use selected combinations of indices to single out {alpha}-enhanced stars without requiring previous knowledge of their main atmospheric parameters. By applying this approach to the total data set, we obtain a list of 60 bona fide {alpha}-enhanced stars and of 146 stars with solar-scaled abundances. The properties of the detected {alpha}-enhanced and solar-scaled abundance stars with respect to their [Fe/H] values and kinematics are presented. A clear kinematic distinction between solar-scaled and {alpha}-enhanced stars was found, although a one-to-one correspondence to "thin disk" and "thick disk" components cannot be supported with the present data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/504/3730
- Title:
- Synthetic RGB photometry of bright stars
- Short Name:
- J/MNRAS/504/3730
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although the use of RGB photometry has exploded in the last decades due to the advent of high-quality and inexpensive digital cameras equipped with Bayer-like colour filter systems, there is surprisingly no catalogue of bright stars that can be used for calibration purposes. Since due to their excessive brightness, accurate enough spectrophotometric measurements of bright stars typically cannot be performed with modern large telescopes, we have employed historical 13-colour medium-narrow-band photometric data, gathered with quite reliable photomultipliers, to fit the spectrum of 1346 bright stars using stellar atmosphere models. This not only constitutes a useful compilation of bright spectrophotometric standards well spread in the celestial sphere, the UCM library of spectrophotometric spectra, but allows the generation of a catalogue of reference RGB magnitudes, with typical random uncertainties ~0.01 mag. For that purpose, we have defined a new set of spectral sensitivity curves, computed as the median of 28 sets of empirical sensitivity curves from the literature, that can be used to establish a standard RGB photometric system. Conversions between RGB magnitudes computed with any of these sets of empirical RGB curves and those determined with the new standard photometric system are provided. Even though particular RGB measurements from single cameras are not expected to provide extremely accurate photometric data, the repeatability and multiplicity of observations will allow access to a large amount of exploitable data in many astronomical fields, such as the detailed monitoring of light pollution and its impact on the night sky brightness, or the study of meteors, Solar system bodies, variable stars, and transient objects. In addition, the RGB magnitudes presented here make the sky an accessible and free laboratory for the calibration of the cameras themselves.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1227
- Title:
- Synthetic Stroemgren photometry
- Short Name:
- J/AJ/127/1227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new grid of theoretical color indices for the Stroemgren uvby photometric system has been derived from MARCS model atmospheres and SSG synthetic spectra for cool dwarf and giant stars having -3.0<=[Fe/H]<=+0.5 and 3000<=T_eff_<=8000K. In the present investigation, we have also analyzed the observed Stroemgren photometry for the classic Population II subdwarfs, compared our "final" (b-y)-Teff relationship with those derived empirically in a number of recent studies and examined in some detail the dependence of the m1 index on [Fe/H].
- ID:
- ivo://CDS.VizieR/J/A+A/477/67
- Title:
- Systematic search for M31 novae from Schmidt plates
- Short Name:
- J/A+A/477/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on the detection of optical novae in our neighbour galaxy M 31 based on digitized historical Tautenburg Schmidt plates. The accurate positions of the detected novae lead to a much larger database when searching for recurrent novae in M 31. We conducted a systematic search for novae on 306 digitized Tautenburg Schmidt plates covering a time span of 36 years from 1960 to 1996. From the database of both ~3x10^5^ light curves and >~10^6^ detections on only one plate per colour band, nova candidates were efficiently selected by automated algorithms and subsequently individually inspected by eye. We report the detection of 84 nova candidates.
15216. System IMF of 25 Ori
- ID:
- ivo://CDS.VizieR/J/MNRAS/486/1718
- Title:
- System IMF of 25 Ori
- Short Name:
- J/MNRAS/486/1718
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar initial mass function (IMF) is an essential input for many astrophysical studies but only in a few cases has it been determined over the whole cluster mass range, limiting the conclusions about its nature. The 25 Orionis group (25 Ori) is an excellent laboratory for investigating the IMF across the entire mass range of the population, from planetary-mass objects to intermediate/high-mass stars. We combine new deep optical photometry with optical and near-infrared data from the literature to select 1687 member candidates covering a 1.1{deg} radius area in 25 Ori. With this sample we derived the 25 Ori system IMF from 0.012 to 13.1M_{sun}_. This system IMF is well described by a two-segment power law with {GAMMA}=-0.74+/-0.04 for m<0.4M_{sun}_ and {GAMMA}=1.50+/-0.11 for m>=0.4M_{sun}_. It is also well described over the whole mass range by a tapered power-law function with {GAMMA}=1.10+/-0.09, mp=0.31+/-0.03 and {beta}=2.11+/-0.09. The best lognormal representation of the system IMF has mc=0.31+/-0.04 and {sigma}=0.46+/-0.05 for m<1M_{sun}_. This system IMF does not present significant variations with the radii. We compared the resultant system IMF as well as the brown dwarf/star ratio of 0.16+/-0.03 that we estimated for 25 Ori with that of other stellar regions with diverse conditions and found no significant discrepancies. These results support the idea that general star-formation mechanisms are probably not strongly dependent on environmental conditions. We found that the substellar and stellar objects in 25 Ori do not have any preferential spatial distributions and confirmed that 25 Ori is a gravitationally unbound stellar association.
- ID:
- ivo://CDS.VizieR/J/A+A/445/819
- Title:
- Systems of galaxies in Shapley supercluster
- Short Name:
- J/A+A/445/819
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the largest compilation of galaxies with redshift in the region of the Shapley Supercluster (Proust et al., 2004 in prep., 2006A&A...447..133P), we identified 122 galaxy systems, 60 of which are new systems. Using the SuperCOSMOS catalogue, we have assigned b_j_ magnitudes to each galaxy in our compilation. The sample of galaxy systems was used to estimate the mass function of systems in the range 10^13^ to 10^15^M_{sun}/h^-1^. We computed a lower value to the total mass in the region of the Shapley Supercluster with this mass function. Using 15 mock catalogues we derived the mean mass that these kinds of systems have before comparing it with that obtained from the real data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/248
- Title:
- 44 SZ-selected galaxy clusters ACT observations
- Short Name:
- J/MNRAS/461/248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using N-body simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses M_200_ are in the range (1-15)x10^14^M_{sun}_. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray observations gives a mean SZ-to-dynamical mass ratio of 1.10+/-0.13, but there is an additional 0.14 systematic uncertainty due to the unknown velocity bias; the statistical uncertainty is dominated by the scatter in the mass-velocity dispersion scaling relation. This ratio is consistent with previous determinations at these mass scales.
- ID:
- ivo://CDS.VizieR/J/ApJ/639/724
- Title:
- Tadpole galaxies in the Hubble UDF
- Short Name:
- J/ApJ/639/724
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the Hubble Ultra Deep Field (HUDF, Cat. <II/258>) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These "tadpole galaxies" appear dynamically unrelaxed - presumably in an early merging stage - where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole galaxies from the HUDF and study their properties as a function of their photometric redshifts.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A138
- Title:
- Taffy system CO(1-0) datacube
- Short Name:
- J/A+A/647/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Taffy system (UGC 12914/15) consists of two massive spiral galaxies which had a head-on collision about 20Myr ago. New sensitive, high-resolution CO(1-0) observations of the Taffy system with the IRAM PdBI are presented. About 25% of the total interferometric CO luminosity stems from the bridge region. Assuming a Galactic N(H2)/ICO conversion factor for the galactic disks and a third of this value for the bridge gas, about 10% of the molecular gas mass is located in the bridge region. The giant HII region close to UGC 12915 is located at the northern edge of the high-surface brightness giant molecular cloud association (GMA), which has the highest velocity dispersion among the bridge GMAs. The bridge GMAs are clearly not virialized because of their high velocity dispersion. Three dynamical models are presented and while no single model reproduces all of the observed features, they are all present in at least one of the models. Most of the bridge gas detected in CO does not form stars. We suggest that turbulent adiabatic compression is responsible for the exceptionally high velocity dispersion of the molecular ISM and the suppression of star formation in the Taffy bridge. In this scenario the turbulent velocity dispersion of the largest eddies and turbulent substructures/clouds increase such that giant molecular clouds are no longer in global virial equilibrium. The increase of the virial parameter leads to a decrease of the star formation efficiency. Most of the low-surface density, CO-emitting gas will disperse without forming stars but some of the high-density gas will probably collapse and form dense star clusters, such as the luminous HII region close to UGC 12915. We suggest that globular clusters and super star clusters formed and still form through the gravitational collapse of gas previously compressed by turbulent adiabatic compression during galaxy interactions.
![To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to the catalogue of astrometric microlensing events. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice. .. image:: /static/img/cc0.png :alt: [CC0]](/registry-search/?f%5BcapabilityType_facet%5D%5B%5D=Simple+Cone+Search&f%5Brights_facet%5D%5B%5D=To+the+extent+possible+under+law%2C+the+publisher+has+waived+all+copyright+and+related+or+neighboring+rights+to+the+catalogue+of+astrometric+++microlensing+events.++For+details%2C+see+the+%60Creative+Commons+CC0+1.0+Public+Domain+dedication+%3Chttp%3A%2F%2Fcreativecommons.org%2Fpublicdomain%2Fzero%2F1.0%2F%3E%60_.++Of+course%2C+you+should+still+give+proper+credit+when+using+this+data+as+required+by+good+scientific+practice.%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fcc0.png%0A+++%3Aalt%3A+%5BCC0%5D%0A%0A){kind=link}