- ID:
- ivo://CDS.VizieR/J/ApJS/154/623
- Title:
- M31 Long Period Variables : Photometry
- Short Name:
- J/ApJS/154/623
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A significant fraction of the disk of M31 has been surveyed for long-period variable stars. We report the results, including near-infrared photometry of almost 2000 variables, and light curves in the i band. The period-luminosity relation suggests that most of the variables are asymptotic giant branch stars, and their luminosity function can be understood in terms of mass-loss rates, which increase with increasing luminosity on the giant branch, and star formation rates, which were a few times higher a billion years ago in M31 than they are today. We see some supergiant long-period variables, but somewhat fewer than expected based on their frequency in M33, and confined to the ring of star formation in M31 seen in the IRAS and 2MASS surveys.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/592/A51
- Title:
- 3mm and 1mm spectra of IRC +10420
- Short Name:
- J/A+A/592/A51
- Date:
- 24 Nov 2021 07:04:25
- Publisher:
- CDS
- Description:
- Our knowledge of the chemical properties of the circumstellar ejecta of the most massive evolved stars is particularly poor. We aim to study the chemical characteristics of the prototypical yellow hypergiant star, IRC +10420. For this purpose, we obtained full line surveys at 1 and 3mm atmospheric windows. We have identified 106 molecular emission lines from 22 molecular species. Approximately half of the molecules detected are N-bearing species, in particular HCN, HNC, CN, NO, NS, PN, and N_2_H. We used rotational diagrams to derive the density and rotational temperature of the different molecular species detected. We introduced an iterative method that allows us to take moderate line opacities into account.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A116
- Title:
- Monitoring of the V777 Her star KUV 05134+2605
- Short Name:
- J/A+A/570/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- KUV 05134+2605 is one of the 21 pulsating DB white dwarfs (V777 Her or DBV variables) known so far. The detailed investigation of the short-period and low-amplitude pulsations of these relatively faint targets requires considerable observational efforts from the ground, long-term single-site or multi-site observations. The observed amplitudes of excited modes undergo short-term variations in many cases, which makes determining pulsation modes difficult. We aim to determine the pulsation frequencies of KUV 05134+2605, find regularities between the frequency and period components, and perform an asteroseismic investigation for the first time.
- ID:
- ivo://CDS.VizieR/J/A+A/371/986
- Title:
- Monoperiodic pulsating stars in the OGLE database
- Short Name:
- J/A+A/371/986
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Files table3, table4, table5 contain the parameters of the Fourier fits of the light curves of monoperiodic OGLE variables with P<1d (High-Amplitude {delta} Scuti (HADS), RRc and RRab stars respectively).
- ID:
- ivo://CDS.VizieR/J/AcA/58/279
- Title:
- Moscow Digital Variables in Field of 66 Oph
- Short Name:
- J/AcA/58/279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We initiated digitization of the Moscow collection of astronomical plates using flatbed scanners. Techniques of photographic photometry of the digital images were applied, enabling an effective search for new variable stars. Our search for new variables among 140000 stars in the 10{deg}x5{deg} northern half of the field centered at 66 Oph, photographed with the Sternberg Institute's 40-cm astrograph in 1976-1995, gave 274 new discoveries, among them: 2 probable Population II Cepheids, 81 eclipsing variables, 5 high-amplitude delta Sct stars (HADSs), 82 RR Lyr stars, 62 red irregular variables and 41 red semiregular stars, 1 slow irregular variable not red in color. Ephemerides were determined for periodic variable stars. We detected about 30 variability suspects for follow-up CCD observations, confirmed 11 stars from the New Catalog of Suspected Variable Stars, and derived new ephemerides for 2 stars already contained in the General Catalog of Variable Stars.
- 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/AJ/118/453
- Title:
- M9 RR Lyrae CCD observations
- Short Name:
- J/AJ/118/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD observations have been used to study 16 of the previously known variables in the Oosterhoff type II globular cluster M9. The properties of the RR Lyrae variables in M9 are compared with those in the Oosterhoff type I cluster M3. Methods devised by Simon, Jurcsik, & Kovacs have been used to derive physical parameters for the stars from Fourier analysis. The mean metal abundance so derived for M9, [Fe/H]=-1.77, is in good agreement with the metal abundance derived from spectroscopic observations. All methods for calculating the absolute magnitudes of RR Lyrae variables from Fourier coefficients indicate that the RR Lyrae variables in M9 are more luminous than those in M3. However, there are three RR Lyrae stars in M3 that may be as bright as the M9 stars. These three are thought to be in a more advanced evolutionary state than the other M3 RR Lyrae stars. Absolute magnitudes have also been derived for the RR Lyrae stars in M68 and M107. The different methods predict that RR Lyrae stars in metal-poor clusters are more luminous than those in more metal-rich clusters, but there are inconsistencies in the relative luminosities derived by the different methods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/461/1032
- Title:
- M5 RR Lyrae times of maxima
- Short Name:
- J/MNRAS/461/1032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Secular period variations, {beta}=dP/dt, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD V photometry and the historical photometric data base available in the literature since 1889. This provides a time baseline of up to 118 yr for these variables. The analysis was performed using two independent approaches: first, the classical O-C behaviour of the time of maximum light, and second, via a grid (P, {beta}), where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in 96 per cent of the stars studied no irregular or stochastic variations need to be claimed, but that 66 per cent of the population shows steady period increases or decreases, and that 34 per cent of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of {beta} and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/361.175
- Title:
- M5 RR Lyr and HB VI light curves
- Short Name:
- J/other/ApSS/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the distance and [Fe/H] value for the globular cluster NGC 5904 (M5) derived from the Fourier decomposition of the light curves of selected RRab and RRc stars. The aim in doing this was to bring these parameters into the homogeneous scales established by our previous work on numerous other globular clusters, allowing a direct comparison of the horizontal branch luminosity in clusters with a wide range of metallicities. Our CCD photometry of the large variable star population of this cluster is used to discuss light curve peculiarities, like Blazhko modulations, on an individual basis. New Blazhko variables are reported. From the RRab stars we found [Fe/H]UVES=-1.335+/-0.003(statistical)+/-0.110(systematic), and a distance of 7.6+/-0.2kpc, and from the RRc stars we found [Fe/H]UVES=-1.39+/-0.03(statistical)+/-0.12(systematic) and a distance of 7.5+/-0.3kpc. The results for RRab and RRc stars should be considered independent since they come from different calibrations and zero points. Absolute magnitudes, radii and masses are also reported for individual RR Lyrae stars. The distance to the cluster was also calculated by alternative methods like the Period-Luminosity relation of SX Phe and the luminosity of the stars at the tip of the red giant branch, and we obtained the results 7.7+/-0.4 and 7.2-7.5kpc respectively. The distribution of RR Lyrae stars in the instability strip is discussed and compared with other clusters in connection with the Oosterhoff and horizontal branch type. The Oosterhoff type II clusters systematically show a RRab-RRc segregation about the instability strip first-overtone red edge, while the Oosterhoff type I clusters may or may not display this feature. A group of RR Lyrae stars is identified in an advanced evolutionary stage, and two of them are likely binaries with unseen companions.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A100
- Title:
- M-type AGB stars wind and dust models
- Short Name:
- J/A+A/626/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar winds of asymptotic giant branch (AGB) stars are commonly attributed to radiation pressure on dust grains, formed in the wake of shock waves that arise in the stellar atmospheres. The mass loss due to these outflows is substantial, and modelling the dynamical properties of the winds is essential both for studies of individual stars and for understanding the evolution of stellar populations with low to intermediate mass. The purpose of this work is to present an extensive grid of dynamical atmosphere and wind models for M-type AGB stars, covering a wide range of relevant stellar parameters. We used the DARWIN code, which includes frequency-dependent radiation-hydrodynamics and a time-dependent description of dust condensation and evaporation, to simulate the dynamical atmosphere. The wind-driving mechanism is photon scattering on submicron-sized Mg2SiO4 grains. The grid consists of ~4000 models, with luminosities from L*=890L_{sun}_ to L*=40000 L_{sun}_ and effective temperatures from 2200 to 3400K. For the first time different current stellar masses are explored with M-type DARWIN models, ranging from 0.75M_{sun}_ to 3 M_{sun}_. The modelling results are radial atmospheric structures, dynamical properties such as mass-loss rates and wind velocities, and dust properties (e.g. grain sizes, dust-to-gas ratios, and degree of condensed Si). We find that the mass-loss rates of the models correlate strongly with luminosity. They also correlate with the ratio L*/M*: increasing L*/M* by an order of magnitude increases the mass-loss rates by about three orders of magnitude, which may naturally create a superwind regime in evolution models. There is, however, no discernible trend of mass-loss rate with effective temperature, in contrast to what is found for C-type AGB stars. We also find that the mass-loss rates level off at luminosities higher than ~14000L_{sun}_, and consequently at pulsation periods longer than ~800 days. The final grain radii range from 0.25 to 0.6um. The amount of condensed Si is typically between 10 and 40%, with gas-to-dust mass ratios between 500 and 4000.
