- 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.
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Search Results
- 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.
1243. 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.
- 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.
- 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.
- 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).
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/893/67
- Title:
- Smoothed amplitudes from Kepler, K2 and TESS phot.
- Short Name:
- J/ApJ/893/67
- Date:
- 03 Dec 2021 00:35:27
- Publisher:
- CDS
- Description:
- We investigate starspot distributions consistent with space-based photometry of F, G, and K stars in six stellar associations ranging in age from 10Myr to 4Gyr. We show that a simple light-curve statistic called the "smoothed amplitude" is proportional to stellar age as t^-1/2^, following a Skumanich-like spin-down relation. We marginalize over the unknown stellar inclinations by forward modeling the ensemble of light curves for direct comparison with the Kepler, K2, and TESS photometry. We sample the posterior distributions for spot coverage with approximate Bayesian computation. We find typical spot coverages in the range 1%-10%, which decrease with increasing stellar age. The spot coverage is proportional to t^n^ where n=-0.37+/-0.16, also statistically consistent with a Skumanich-like t^-1/2^ decay of starspot coverage with age. We apply two techniques to estimate the spot coverage of young exoplanet-hosting stars likely to be targeted for transmission spectroscopy with the James Webb Space Telescope, and estimate the bias in exoplanet radius measurements due to varying starspot coverage.
- ID:
- ivo://CDS.VizieR/J/A+A/406/L23
- Title:
- Solar-like oscillations in alpha Cen B
- Short Name:
- J/A+A/406/L23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K1 dwarf alpha Cen B was observed with the CORALIE spectrograph on the 1.2-m Swiss telescope at La Silla in April 2003. Thirteen nights of observations have made it possible to collect 3626 radial velocity measurements with a standard deviation of 1.4m/s exhibiting a mean noise level in the amplitude spectrum of only 3.75cm/s. Twelve oscillation modes have been identified in the power spectrum between 3 and 4.6mHz with amplitudes in the range 8.7 to 13.7cm/s and showing a regularity with a large separation of 161.1uHz.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/2251
- Title:
- Southern Catalina Survey type-ab RR Lyrae
- Short Name:
- J/MNRAS/446/2251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a deep, wide-area variability survey in the Southern hemisphere. As part of the Catalina Sky Surveys, the Siding Spring Survey (SSS) has covered 14,800 square degrees in the declination range of -75{deg}<delta<-15{deg} To mine the enormous SSS dataset efficiently we have developed two algorithms: Automatic Period Selection (APS) and Automatic Fourier Decomposition (AFD), which aim to sharpen the period estimation and produce robust lightcurve models. Armed with the APS and AFD outputs we classify 10540 ab-type RR Lyrae (RRab) stars (~90% of which are new) across the Southern sky.
