- ID:
- ivo://CDS.VizieR/J/AJ/151/49
- Title:
- M6 open cluster: star members properties
- Short Name:
- J/AJ/151/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the first abundance analysis of 44 late B-, A-, and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myr). Low- and medium-resolution spectra, covering the 4500-5840 {AA} wavelength range, were obtained using the FLAMES/GIRAFFE spectrograph attached to the ESO Very Large Telescopes. We determined the atmospheric parameters using calibrations of the Geneva photometry and by adjusting the H_{beta}_ profiles to synthetic ones. The abundances of up to 20 chemical elements, from helium to mercury, were derived for 19 late B, 16 A, and 9 F stars by iteratively adjusting synthetic spectra to the observations. We also derived a mean cluster metallicity of [Fe/H]=0.07+/-0.03 dex from the iron abundances of the F-type stars. We find that for most chemical elements, the normal late B- and A-type stars exhibit larger star-to-star abundance variations than the F-type stars probably because of the faster rotation of the B and A stars. The abundances of C, O, Mg, Si, and Sc appear to be anticorrelated with that of Fe, while the opposite holds for the abundances of Ca, Ti, Cr, Mn, Ni, Y, and Ba as expected if radiative diffusion is efficient in the envelopes of these stars. In the course of this analysis, we discovered five new peculiar stars: one mild Am, one Am, and one Fm star (HD 318091, CD-32 13109, GSC 07380-01211, CP1), one HgMn star (HD 318126, CP3), and one He-weak P-rich (HD 318101, CP4) star. We also discovered a new spectroscopic binary, most likely a SB2. We performed a detailed modeling of HD 318101, the new He-weak P-rich CP star, using the Montreal stellar evolution code XEVOL which self-consistently treats all particle transport processes. Although the overall abundance pattern of this star is properly reproduced, we find that detailed abundances (in particular the high P excess) resisted modeling attempts even when a range of turbulence profiles and mass-loss rates were considered. Solutions are proposed which are still under investigation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/146/151
- Title:
- Morphology catalog of nearby galaxies from SDSS DR7
- Short Name:
- J/AJ/146/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the statistical properties of a volume-limited sample of 7429 nearby (z=0.033-0.044) galaxies from the Sloan Digital Sky Survey Data Release 7. Our database includes morphology distribution as well as the structural and spectroscopic properties of each morphology type based on the recent remeasurements of spectral line strengths by Oh and collaborators. Our database does not include galaxies that are apparently smaller and flatter because morphology classification of them turned out to be difficult. Our statistics confirmed the up-to-date knowledge of galaxy populations, e.g., correlations between morphology and line strengths as well as the derived ages. We hope that this database will be useful as a reference.
- ID:
- ivo://CDS.VizieR/J/A+A/415/863
- Title:
- Mount Stromlo Abell Cluster Supernova Search
- Short Name:
- J/A+A/415/863
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 1 lists SNe discovered by the Mount Stromlo Abell Cluster Supernova Search. The SNIa? were classified through the goodness of fit of the template light curves and hence could be SNe of another type that have been misclassified. Those SNe designated nIa were deemed not to be SNIa through the template fits and were not investigated further. Table 3 contains Maximum light magnitudes, {Delta}m15 values and distances derived from the template light curve fitting technique for those SNe from the Mount Stromlo Abell Cluster Supernova Search deemed to be SNIa, as well as those from Phillips (1999AJ....118.1766P) The subdirectory "comp" contains the files with calibrated magnitudes for the local standard stars found in the field of each of the supernovae from the Mount Stromlo Abell Cluster Supernova Search. The numbering of these stars corresponds to that found in the finding charts of each of these fields. These are found online at EDP Sciences. For each local standard, their Cousins B, V, R and I magnitudes are given, as is the error in the magnitude estimate. The subdirectory "flux" contains the files with calibrated fluxes for the supernovae discovered in the Mount Stromlo Abell Cluster Supernova Search. For each supernova, the MACHO VM, RM magnitudes and Cousins B, V, R and I fluxes are given (when available), as are the errors in the derived fluxes. One unit flux is equivalent to 25th magnitude. The subdirectory "mag" contains the files with calibrated magnitudes for the supernovae discovered in the Mount Stromlo Abell Cluster Supernova Search. For each supernova, the MACHO VM, RM magnitudes and Cousins B, V, R and I magnitudes are given (when available), as is the upper and lower errors in the derived magnitudes.
- ID:
- ivo://CDS.VizieR/J/AJ/124/234
- Title:
- M31 outer halo UBVRI photometry and metallicity
- Short Name:
- J/AJ/124/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10m telescope and Low Resolution Imaging Spectrograph of the Ca II near-infrared triplet in 99 M31 halo candidates in a field at R=19kpc on the southeast minor axis with brightnesses from 20<I<22.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/59
- Title:
- M31 PAndromeda Cepheid sample in four HST bands
- Short Name:
- J/ApJ/864/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the M31 PAndromeda Cepheid sample and the HST PHAT data we obtain the largest Cepheid sample in M31 with HST data in four bands. For our analysis we consider three samples: A very homogeneous sample of Cepheids based on the PAndromeda data, the mean magnitude corrected PAndromeda sample and a sample complementing the PAndromeda sample with Cepheids from literature. The latter results in the largest catalog with 522 fundamental mode (FM) Cepheids and 102 first overtone (FO) Cepheids with F160W and F110W data and 559 FM Cepheids and 111 FO Cepheids with F814W and F475W data. The obtained dispersion of the Period-Luminosity relations (PLRs) is very small (e.g. 0.138mag in the F160W sample I PLR). We find no broken slope in the PLRs when analyzing our entire sample, but we do identify a subsample of Cepheids that causes the broken slope. However, this effect only shows when the number of this Cepheid type makes up a significant fraction of the total sample. We also analyze the sample selection effect on the Hubble constant.
- ID:
- ivo://CDS.VizieR/J/ApJS/240/31
- Title:
- M-subdwarf research. I. LAMOST DR4 spectra obs.
- Short Name:
- J/ApJS/240/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a revision of the system developed by Lepine+ (2007ApJ...669.1235L) for spectroscopic M-subdwarf classification. Based on an analysis of subdwarf spectra and templates from Savcheva+ (2014ApJ...794..145S), we show that the CaH1 feature originally proposed by Gizis (1997, J/AJ/113/806) is important in selecting reliable cool subdwarf spectra. This index should be used in combination with the [TiO5, CaH2+CaH3] relation provided by Lepine+ to avoid misclassification results. In the new system, the dwarf-subdwarf separators are first derived from a sample of more than 80000 M dwarfs and a "labeled" subdwarf subsample, and these objects are all visually identified from their optical spectra. Based on these two samples, we refit the initial [TiO5, CaH1] relation and propose a new [CaOH, CaH1] relation supplementing the [TiO5, CaH1] relation to reduce the impact of uncertainty in flux calibration on classification accuracy. In addition, we recalibrate the {zeta}TiO/CaH parameter defined in Lepine+ to enable its successful application to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. Using this new system, we select candidates from LAMOST Data Release 4 and finally identify a set of 2791 new M-subdwarf stars, covering the spectral sequence from type M0 to M7. This sample contains a large number of objects located at low Galactic latitudes, especially in the Galactic anti-center direction, expanding beyond previously published halo- and thick disk-dominated samples. Besides, we detect magnetic activity in 141 objects. We present a catalog for this M-subdwarf sample, including radial velocities, spectral indices and errors, and activity flags, with a compilation of external data (photometric and Gaia Data Release 2 astrometric parameters).
- ID:
- ivo://CDS.VizieR/J/ApJS/243/28
- Title:
- M-type star magnetic activities from LAMOST & Kepler
- Short Name:
- J/ApJS/243/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a statistical study of magnetic activities of M-type stars by combining the spectra of LAMOST DR5 with light curves from the Kepler and K2 missions. We mainly want to study the relationship between chromospheric activity and flares, and their relations of magnetic activity and rotation period. We have obtained the maximum catalog of 516688 M-type stellar spectra of 480912 M stars from LAMOST-DR5 and calculated their equivalent widths of chromospheric activity indicators (H{alpha}, H{beta}, H{gamma}, H{delta}, CaII H&K, and HeI D3). Using the H{alpha} indicator, 40464 spectra of 38417 M stars show chromospheric activity, and 1791 of these 5499 M-type stars with repeated observations have H{alpha} variability. We used an automatic detection plus visual inspection method to detect 17432 flares on 8964 M-type stars from the catalog by cross-matching LAMOST DR5 and the Kepler and K2 databases. We used the Lomb-Scargle method to calculate their rotation periods. We find that the flare frequency is consistent with the ratio of activities of these chromospheric activity indicators as a function of spectral type in M0-M3. We find the equivalent widths of H{alpha} and CaII H have a significant statistical correlation with the flare amplitude in M-type stars. We confirm that the stellar flare is affected by both the stellar magnetic activity and the rotation period. Finally, using the H{alpha} equivalent width equal to 0.75{AA} and using the rotation period equal to 10 days as the threshold for the M-type stellar flare time frequency are almost equivalent.
- ID:
- ivo://CDS.VizieR/J/AJ/124/1486
- Title:
- M4 UBV color-magnitude diagrams
- Short Name:
- J/AJ/124/1486
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBV color-magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V<-0.6), which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the presence of a population of faint blue objects, likely to be hot, young white dwarfs belonging to the cluster. We have selected five objects above V=22mag, bright enough for follow-up ground-based spectroscopy, and present their coordinates and finding charts. We show a spectrum for variable V46, which suggests that it is a hot subdwarf, along with a new light curve obtained with the ISIS image subtraction package. The light curve is unstable, but only one period of variability is apparent. Two new variables have been discovered, both located on the cluster red giant branch. We also present a differential E(B-V) reddening map and a fiducial sequence for the main sequence, subgiant branch, and red giant branch on the V/B-V CMD for a selected region with uniform reddening. Based on a comparison with the M5 fiducial sequence, we obtain a reddening estimate of E(B-V)=0.41mag toward M4, consistent with previous determinations.
589. M30 UBV photometry
- ID:
- ivo://CDS.VizieR/J/AJ/116/1757
- Title:
- M30 UBV photometry
- Short Name:
- J/AJ/116/1757
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in the central 2' of the dense, post-core-collapse cluster M30 (NGC 7099) derived from Hubble Space Telescope Wide Field Planetary Camera 2 images. These data are used to study the mix of stellar populations in the central region of the cluster. Forty-eight blue straggler stars are identified; they are found to be strongly concentrated toward the cluster center. The specific frequency of blue stragglers, F_BSS_=N(BSS)/N(V<V_HB_+2), is 0.25+/-0.05 in the inner region of M30 (r<20"), significantly higher than the frequency found in other clusters: F_BSS_=0.05-0.15. The shape of M30's blue straggler luminosity function resembles the prediction of the collisional formation model, and is inconsistent with the binary merger model of Bailyn & Pinsonneault (1995ApJ...439..705B). An unusually blue star (B=18.6, B-V=-0.97), possibly a cataclysmic variable based on its color, is found about 1.2" from the crowded cluster center; the photometric uncertainty for this star is large, however, because of the presence of a very close neighbor. Bright red giant stars (B<16.6) appear to be depleted by a factor of 2-3 in the inner r<10" relative to fainter giants, subgiants, and main-sequence turnoff stars (95% significance). We confirm that there is a radial gradient in the color of the overall cluster light, going from B-V~0.82 at r~1' to B-V~0.45 in the central 10". The central depletion of the bright red giants is responsible for about half of the observed color gradient; the rest of the gradient is caused by the relative underabundance of faint red main-sequence stars near the cluster center (presumably a result of mass segregation). The luminosity function of M30's evolved stars does not match the luminosity function shape derived from standard stellar evolutionary models: the ratio of the number of bright giants to the number of turnoff stars in the cluster is 30% higher than predicted by the model (3.8{sigma} effect), roughly independent of red giant brightness over the range M_V_=-2 to +2.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A10
- Title:
- Multiband surface photometry of 21 BCGs
- Short Name:
- J/A+A/556/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep surface photometry of a volume-limited sample of 21 UM emission line galaxies in broadband optical UBVRI and near infra-red (NIR) HKs filters. The sample comprises 19 blue compact galaxies (BCGs) and two spirals. For some targets the exposure times are the deepest to date. For the BCG UM462 we observe a previously undetected second disk component beyond a surface brightness level of mu_B_=26mag/arcsec^2^. This is a true low surface brightness component with central surface brightness mu_0_=24.1mag/arcsec^2^ and scale length h_r_=1.5kpc. All BCGs are dwarfs, with M_B_>=-18, and very compact, with an average scale length of h_r_~1kpc. We separate the burst and host populations for each galaxy and compare them to stellar evolutionary models with and without nebular emission contribution. We also measure the A_180_ asymmetry in all filters and detect a shift from optical to NIR in the average asymmetry of the sample. This shift seems to be correlated with the morphological class of the BCGs. Using the color-asymmetry relation, we identify five BCGs in the sample as mergers, which is confirmed by their morphological class. Though clearly separated from normal galaxies in the concentration-asymmetry parameter space, we find that it is not possible to distinguish luminous starbursting BCGs from the merely star forming low luminosity BCGs.
