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5711. RR Lyr variable stars in M32
ID:
ivo://CDS.VizieR/J/A+A/539/A138
Title:
RR Lyr variable stars in M32
Short Name:
J/A+A/539/A138
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using archival multi-epoch ACS/WFC images in the F606W and F814W filters of a resolved stellar field in Local Group dwarf elliptical galaxy M 32 we have made an accurate Colour-Magnitude Diagram and a careful search for RR Lyr variable stars. We identified 416 bona fide RR Lyr stars over our field of view, and their spatial distribution shows a rising number density towards the centre of M 32. These new observations clearly confirm the tentative result of Fiorentino et al. (2010ApJ...708..817F), on a much smaller field of view, associating an ancient population of RR Lyr variables to M 32. We associate at least 83 RR Lyr stars in our field to M 32.
5712. RR Tel JHKL photometry 1975-2002
ID:
ivo://CDS.VizieR/J/A+A/452/503
Title:
RR Tel JHKL photometry 1975-2002
Short Name:
J/A+A/452/503
Date:
21 Oct 2021
Publisher:
CDS
Description:
A set of photometric observations of the symbiotic nova RR Tel in different wavelength bands - visual from 1949 to 2002 and near-infrared (JHKL) from 1975 to 2002 - are presented. Near-infrared photometry is used to identify and study three periods during which the Mira component was heavily obscured by dust. The variability due to the normal Mira pulsation was removed from the JHKL data, which were then compared with the AAVSO visual light curve. We discuss these obscuration events as observed in the different wavelength bands. A change in the colour trend was observed with the colour becoming redder after JD2446000. Generally J-K was comparable while K-L was larger than typical values for solitary Miras. A distance estimate of 2.5kpc, based on the IR data, is given. A study of the behaviour of the permitted Fe II and forbidden [FeII] emission lines during the 1996-2000 obscuration episode suggests a larger flux decrease for the permitted than for the forbidden lines. No other correlation with line properties have been found. The most attractive model involves obscuration by optically thick clouds in the outer layers.
5713. RSG and foreground candidates in M31
ID:
ivo://CDS.VizieR/J/ApJ/826/224
Title:
RSG and foreground candidates in M31
Short Name:
J/ApJ/826/224
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the red supergiant (RSG) population of M31, obtaining the radial velocities of 255 stars. These data substantiate membership of our photometrically selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 M_{sun}_ stars, while the vast majority evolved from stars with initial masses of 20 M_{sun}_ or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; i.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested.
5714. RSGs in the LMC & sp. follow-up for LMC & SMC
ID:
ivo://CDS.VizieR/J/ApJ/900/118
Title:
RSGs in the LMC & sp. follow-up for LMC & SMC
Short Name:
J/ApJ/900/118
Date:
20 Jan 2022 11:32:23
Publisher:
CDS
Description:
The binary fraction of unevolved massive stars is thought to be 70%-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of these stars, the red supergiants (RSGs). Here we identify a complete sample of RSGs in the Large Magellanic Cloud (LMC) using new spectroscopic observations and archival UV, IR, and broadband optical photometry. We find 4090 RSGs with logL/L_{sun}_>3.5, with 1820 of them having logL/L_{sun}_>4, which we believe is our completeness limit. We additionally spectroscopically confirmed 38 new RSG + B-star binaries in the LMC, bringing the total known up to 55. We then estimated the binary fraction using a k-nearest neighbors algorithm that classifies stars as single or binary based on photometry with a spectroscopic sample as a training set. We take into account observational biases such as line-of-sight stars and binaries in eclipse while also calculating model- dependent corrections for RSGs with companions that our observations were not designed to detect. Based on our data, we find an initial result of 13.5_-6.67_^+7.56^% for RSGs with O- or B-type companions. Using the Binary Population and Spectral Synthesis models to correct for unobserved systems, this corresponds to a total RSG binary fraction of 19.5_-6.7_^+7.6^% . This number is in broad agreement with what we would expect given an initial OB binary distribution of 70%, a predicted merger fraction of 20%-30%, and a binary interaction fraction of 40%-50%.
5715. RT Aur and SZ tau UBV light curves
ID:
ivo://CDS.VizieR/J/MNRAS/446/4008
Title:
RT Aur and SZ tau UBV light curves
Short Name:
J/MNRAS/446/4008
Date:
21 Oct 2021
Publisher:
CDS
Description:
The quantity and quality of satellite photometric data strings is revealing details in Cepheid variation at very low levels. Specifically, we observed a Cepheid pulsating in the fundamental mode and one pulsating in the first overtone with the Canadian MOST (Microvariability and Oscillations of Stars) satellite. The 3.7-d period fundamental mode pulsator (RT Aur) has a light curve that repeats precisely, and can be modelled by a Fourier series very accurately. The overtone pulsator (SZ Tau, 3.1d period) on the other hand shows light-curve variation from cycle to cycle which we characterize by the variations in the Fourier parameters. We present arguments that we are seeing instability in the pulsation cycle of the overtone pulsator, and that this is also a characteristic of the O-C curves of overtone pulsators. On the other hand, deviations from cycle to cycle as a function of pulsation phase follow a similar pattern in both stars, increasing after minimum radius. In summary, pulsation in the overtone pulsator is less stable than that of the fundamental mode pulsator at both long and short time-scales.
5716. RU Eri UBV differential light curves
ID:
ivo://CDS.VizieR/J/PASP/125/17
Title:
RU Eri UBV differential light curves
Short Name:
J/PASP/125/17
Date:
21 Oct 2021
Publisher:
CDS
Description:
RU Eri is a near-contact eclipsing binary (V~9.24mag) with a 0.632-day orbital period. The Wilson-Devinney program is used to simultaneously solve new UBV light curves obtained between 1973 and 1981 at the Fernbank Science Center Observatory, together with existing single-lined radial velocity measurements. Light and velocity solution parameters, orbital elements, and absolute dimensions are presented. A period of 0.632198836+/-0.000000046d is found.
5717. Runaway stars in the 30 Doradus region of the LMC
ID:
ivo://CDS.VizieR/J/AJ/156/98
Title:
Runaway stars in the 30 Doradus region of the LMC
Short Name:
J/AJ/156/98
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of relative proper motions for 368787 stars in the 30 Doradus region of the Large Magellanic Cloud (LMC), based on a dedicated two-epoch survey with the Hubble Space Telescope and supplemented with proper motions from our pilot archival study. We demonstrate that a relatively short epoch difference of three years is sufficient to reach a level of precision of ~0.1 mas/yr or better. A number of stars with relative proper motions exceeding a 3{sigma} error threshold represent a mixture of Milky Way denizens and 18 potential LMC runaway stars. Based upon 183 VFTS OB stars with the best proper motions, we conclude that none of them moves faster than ~0.3 mas/yr in each coordinate-equivalent to ~70 km/s. Among the remaining 351 VFTS stars with less accurate proper motions, only one candidate OB runaway can be identified. We rule out any OB star in our sample moving at a tangential velocity exceeding ~120 km/s. The most significant result of this study is finding 10 stars over a wide range of masses that appear to have been ejected from the massive star cluster R136 in the tangential plane to angular distances from 35" out to 407", equivalent to 8-98 pc. The tangential velocities of these runaways appear to be correlated with apparent magnitude, indicating a possible dependence on the stellar mass. Lastly, a comparison to proper motions from Gaia DR 2 shows that for several relatively bright stars the DR 2 has an unexpected scatter that cannot be accounted for by the formal errors.
5718. Ruprecht 147 DANCe. I.
ID:
ivo://CDS.VizieR/J/A+A/625/A115
Title:
Ruprecht 147 DANCe. I.
Short Name:
J/A+A/625/A115
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ruprecht 147 is the oldest (2.5Gyr) open cluster in the solar vicinity (<300pc), making it an important target for stellar evolution studies and exoplanet searches. We aim to derive a census of members and the luminosity, mass, and spatial distributions of the cluster. We used an astro-photometric data set including all available information from the literature together with our own observations. We processed the data with an updated version of an existent membership selection methodology. We identify 259 high-probability candidate members, including 58 previously unreported. All these candidates cover the luminosity interval between G>6mag to i<21mag. The cluster luminosity and mass distributions are derived with an unprecedented level of details allowing us to recognize, among other features, the Wielen dip. The mass distribution in the low-mass regime drops sharply at 0.4M_{sun}_ even though our data are sensitive to stellar masses down to 0.1M_{sun}_, suggesting that most very-low-mass members left the cluster as the result of its dynamical evolution. In addition, the cluster is highly elongated (ellipticity~0.5) towards the galactic plane, and mass segregated. Our combined Gaia+DANCe data set allows us to obtain an extended list of cluster candidate members, and to derive luminosity, mass, and projected spatial distributions in the oldest open cluster of the solar vicinity.
5719. RV and [Fe/H] in 5 open clusters
ID:
ivo://CDS.VizieR/J/A+A/578/A27
Title:
RV and [Fe/H] in 5 open clusters
Short Name:
J/A+A/578/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims. We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. We acquired medium-resolution spectra (R~8000) in the infrared region CaII triplet lines (~8500{AA}) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca ii lines and metallicity were also used to derive the metallicity for each cluster.
5720. RV and g'z' transits of KOI-1089b/Kepler-418b
ID:
ivo://CDS.VizieR/J/A+A/567/A14
Title:
RV and g'z' transits of KOI-1089b/Kepler-418b
Short Name:
J/A+A/567/A14
Date:
21 Oct 2021
Publisher:
CDS
Description:
We announce confirmation of Kepler-418b, one of two proposed planets in this system. This is the first confirmation of an exoplanet based primarily on the transit color signature technique. We used the Kepler public data archive combined with multicolor photometry from the Gran Telescopio de Canarias and radial velocity follow-up using FIES at the Nordic Optical Telescope for confirmation. We report a confident detection of a transit color signature that can only be explained by a compact occulting body, entirely ruling out a contaminating eclipsing binary, a hierarchical triple, or a grazing eclipsing binary. Those findings are corroborated by our radial velocity measurements, which put an upper limit of ~1M_jup_ on the mass of Kepler-418b. We also report that the host star is significantly blended, confirming the ~10% light contamination suspected from the crowding metric in the Kepler light curve measured by the Kepler team. We report detection of an unresolved light source that contributes an additional ~40% to the target star, which would not have been detected without multicolor photometric analysis. The resulting planet-star radius ratio is 0.110+/-0.0025, more than 25% more than the 0.087 measured by Kepler, leading to a radius of 1.20+/-0.16R_jup_ instead of the 0.94R_jup_ measured by the Kepler team. This is the first confirmation of an exoplanet candidate based primarily on the transit color signature, demonstrating that this technique is viable from ground for giant planets. It is particularly useful for planets with long periods such as Kepler-418b, which tend to have long transit durations. While this technique is limited to candidates with deep transits from the ground, it may be possible to confirm earth-like exoplanet candidates with a few hours of observing time with an instrument like the James Webb Space Telescope. Additionally, multicolor photometric analysis of transits can reveal unknown stellar neighbors and binary companions that do not affect the classification of the transiting object but can have a very significant effect on the perceived planetary radius.