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1251. SiO maser survey of nearby red variables
ID:
ivo://CDS.VizieR/J/PASJ/64/4
Title:
SiO maser survey of nearby red variables
Short Name:
J/PASJ/64/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to study the streaming motions of miras in the Solar neighborhood, we newly surveyed 379 red variables in the SiO maser lines at 42.821 and 43.122GHz with the Nobeyama 45m radio telescope. Accurate radial velocities were obtained for 229 (220 new) detected stars. The sample was selected from optical variables found by new automated surveys: the Northern Sky Variability Survey and the All Sky Automated Survey. The new sample consists of "bluer" objects compared with those observed in the previous SiO surveys. The distances to the objects were estimated using the period-luminosity relation, and they are mostly less than 3kpc from the Sun. The longitude-velocity diagram reveals three prominent groups of stars deviant from circular galactic rotation with a flat rotation curve. In addition to the Hercules group of stars, which was studied before, we found two new deviant groups: one toward the Perseus arm and the other toward the Sagittarius arm. These two groups both exhibit anomalous motions toward the galactic center, which seem to be consistent with the noncircular motions of these spiral arms found in recent VLBI proper-motion measurements for maser gas clumps.
1252. Six luminous red novae photometry
ID:
ivo://CDS.VizieR/J/A+A/630/A75
Title:
Six luminous red novae photometry
Short Name:
J/A+A/630/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present extensive datasets for a class of intermediate-luminosity optical transients known as "luminous red novae" (LRNe). They show doublepeaked light curves, with an initial rapid luminosity rise to a blue peak (at -13 to -15mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of three of them (NGC4490-2011OT1, M101-2015OT1, and SNhunt248), likely relatively massive blue to yellow stars, were also observed in a pre-eruptive stage when their luminosity was slowly increasing. Early spectra obtained during the first peak show a blue continuum with superposed prominent narrow Balmer lines, with P Cygni profiles. Lines of FeII are also clearly observed, mostly in emission. During the second peak, the spectral continuum becomes much redder, H{alpha} is barely detected, and a forest of narrow metal lines is observed in absorption. Very late-time spectra (~6 months after blue peak) show an extremely red spectral continuum, peaking in the infrared (IR) domain. H{alpha} is detected in pure emission at such late phases, along with broad absorption bands due to molecular overtones (such as TiO, VO). We discuss a few alternative scenarios for LRNe. Although major instabilities of single massive stars cannot be definitely ruled out, we favour a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. The similarity between LRNe and the outburst observed a few months before the explosion of the Type IIn SN 2011ht is also discussed.
1253. Six occultations of the exoplanet TrES-3
ID:
ivo://CDS.VizieR/J/AJ/136/267
Title:
Six occultations of the exoplanet TrES-3
Short Name:
J/AJ/136/267
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of the exoplanet host star TrES-3 spanning six occultations (secondary eclipses) of its giant planet. No flux decrements were detected, leading to 99%-confidence upper limits on the planet-to-star flux ratio of 2.4x10^-4^, 5.0x10^-4^, and 8.6x10^-4^ in the i-, z-, and R-bands respectively. The corresponding upper limits on the planet's geometric albedo are 0.30, 0.62, and 1.07. The upper limit in the i-band rules out the presence of highly reflective clouds, and is only a factor of 2-3 above the predicted level of thermal radiation from the planet.
1254. Six transits of exoplanet HAT-P-1b
ID:
ivo://CDS.VizieR/J/AJ/134/1707
Title:
Six transits of exoplanet HAT-P-1b
Short Name:
J/AJ/134/1707
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of the G0 star HAT-P-1 during six transits of its close-in giant planet, and we refine the estimates of the system parameters. Relative to Jupiter's properties, HAT-P-1b is 1.20+/-0.05 times larger, and its surface gravity is 2.7+/-0.2 times weaker. Although it remains the case that HAT-P-1b is among the least dense of the known sample of transiting exoplanets, its properties are in accord with previously published models of strongly irradiated, coreless, solar-composition giant planets. The times of the transits have a typical accuracy of 1 minute and do not depart significantly from a constant period.
1255. Six transits of the exoplanet XO-2b
ID:
ivo://CDS.VizieR/J/AJ/137/4911
Title:
Six transits of the exoplanet XO-2b
Short Name:
J/AJ/137/4911
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of six transits of the exoplanet XO-2b. By combining the light-curve analysis with theoretical isochrones to determine the stellar properties, we find the planetary radius to be 0.996^+0.031^_-0.018_R_Jup_ and the planetary mass to be 0.565+/-0.054M_Jup_. These results are consistent with those reported previously, and are also consistent with theoretical models for gas giant planets. The midtransit times are accurate to within 1 minute and are consistent with a constant period. However, the period we derive differs by 2.5{sigma } from the previously published period. More data are needed to tell whether the period is actually variable (as it would be in the presence of an additional body) or if the timing errors have been underestimated.
1256. SMC Be stars candidates
ID:
ivo://CDS.VizieR/J/A+A/393/887
Title:
SMC Be stars candidates
Short Name:
J/A+A/393/887
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recently the OGLE experiment has provided accurate light curves and colours for about 2 millions stars in the Small Magellanic Cloud. We have examined this database for its content of Be stars, applying some selection criteria, and we have found a sample of ~1000 candidates. Some of these stars show beautiful light curves with amazing variations never observed in any Galactic variable. We find outbursts in 13% of the sample (type-1 stars), high and low states in 15%, periodic variations in 7%, and the usual variations seen in Galactic Be stars in 65% of the cases. The Galactic counterparts of type-1 objects could be the outbursting Be stars found by Hubert & Floquet (1998, Cat. J/A+A/335/565) after the analysis of Hipparcos photometry. We discuss the possibility that type-1 stars could correspond to Be stars with accreting white dwarf companions or alternatively, blue pre-main sequence stars surrounded by thermally unstable accretion disks. We provide coordinates and basic photometric information for these stars and some examples of light curves.
1257. SMC Cepheids K-band and RV curves
ID:
ivo://CDS.VizieR/J/A+A/620/A99
Title:
SMC Cepheids K-band and RV curves
Short Name:
J/A+A/620/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
The extragalactic distance scale builds on the Cepheid period-luminosity (PL) relation. Decades of work have not yet convincingly established the sensitivity of the PL relation to metallicity. This currently prevents a determination of the Hubble constant accurate to 1% from the classical Cepheid-SN Ia method. In this paper we carry out a strictly differential comparison of the absolute PL relations obeyed by classical Cepheids in the Milky Way (MW), LMC, and SMC galaxies. Taking advantage of the substantial metallicity difference among the Cepheid populations in these three galaxies, we want to establish a possible systematic trend of the PL relation absolute zero point as a function of metallicity, and to determine the size of such an effect in the optical and near-infrared photometric bands. We used a IRSB Baade-Wesselink-type method to determine individual distances to the Cepheids in our samples in the MW, LMC, and SMC. For our analysis, we used a greatly enhanced sample of Cepheids in the SMC (31 stars) compared to the small sample (5 stars) available in our previous work. We used the distances to determine absolute Cepheid PL relations in the optical and near-infrared bands in each of the three galaxies. Our distance analysis of 31 SMC Cepheids with periods of 4-69 days yields tight PL relations in all studied bands, with slopes consistent with the corresponding LMC and MW relations. Adopting the very accurately determined LMC slopes for the optical and near-infrared bands, we determine the zero point offsets between the corresponding absolute PL relations in the three galaxies. We find that in all bands the metal-poor SMC Cepheids are intrinsically fainter than their more metal-rich counterparts in the LMC and MW. In the K band the metallicity effect is -0.23+/-0.06mag/dex, while in the V,(V-I) Wesenheit index it is slightly stronger, -0.34+/-0.06mag/dex. We find suggestive evidence that the metallicity sensitivity of the PL relation might be nonlinear, being small in the range between solar and LMC Cepheid metallicity, and becoming steeper towards the lower-metallicity regime.
1258. SMC C stars B and R light curves
ID:
ivo://CDS.VizieR/J/A+A/438/521
Title:
SMC C stars B and R light curves
Short Name:
J/A+A/438/521
Date:
21 Oct 2021
Publisher:
CDS
Description:
A sample of carbon-rich stars (C-stars) in the Small Magellanic Cloud (SMC) was selected from the combined 2MASS and DENIS catalogues on the basis of their J-Ks colour. This sample was extended to include confirmed C-stars from the Rebeirot et al. (1993, Cat. <J/A+AS/97/603>) spectroscopic atlas. In this combined sample (N=1149), a smaller number (N=1079) were found to have MACHO observations. For this sub-sample, light curves were determined and 919 stars were found to have high quality light-curves with amplitudes of at least 0.05mag.
1259. SMC RR Lyrae Fourier decomposition
ID:
ivo://CDS.VizieR/J/MNRAS/426/2063
Title:
SMC RR Lyrae Fourier decomposition
Short Name:
J/MNRAS/426/2063
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have performed the Fourier decomposition analysis of 8- and 13-yr V-band light curves of a carefully selected sample of 454 fundamental-mode RR Lyrae variables (RRab type), detected in an ~=14 square degree area of the Small Magellanic Cloud (SMC) and listed in the Optical Gravitational Lensing Experiment, phase III, Catalogue of Variable Stars. The Fourier decomposition parameters were used to derive metal abundances and distance moduli, following the methodology described by Kapakos, Hatzidimitriou & Soszynski, Paper I (2011, Cat. J/MNRAS/415/1366).
1260. SMC RR Lyrae stars light curve analysis
ID:
ivo://CDS.VizieR/J/MNRAS/402/691
Title:
SMC RR Lyrae stars light curve analysis
Short Name:
J/MNRAS/402/691
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a careful and detailed light curve analysis of RR Lyrae stars in the Small Magellanic Cloud (SMC) discovered by the Optical Gravitational Lensing Experiment (OGLE) project. Out of 536 single-mode RR Lyrae stars selected from the data base, we have investigated the physical properties of 335 'normal-looking' RRab stars and 17 RRc stars that have good quality photometric light curves. We have also been able to estimate the distance modulus of the cloud which is in good agreement with those determined from other independent methods.