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- ID:
- ivo://CDS.VizieR/J/other/IBVS/6155
- Title:
- 81th name-list of variable stars. II.
- Short Name:
- J/other/IBVS/615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of a new Name-List of variable stars containing information on 2090 variable stars recently designated in the system of the General Catalogue of Variable Stars. All these stars are in the range of J2000.0 right ascensions from 17 hours 30 minutes to 24 hours.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/1185
- Title:
- Three transits of the exoplanet TrES-2
- Short Name:
- J/ApJ/664/1185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Of the nearby transiting exoplanets that are amenable to detailed study, TrES-2 is both the most massive and the one with the largest impact parameter. We present z-band photometry of three transits of TrES-2. We improve on the estimates of the planetary, stellar, and orbital parameters, in conjunction with the spectroscopic analysis of the host star by Sozzetti and coworkers. We find the planetary radius to be Rp=1.222+/-0.038R_Jup_ and the stellar radius to be R*=1.003+/-0.027R_{sun}_. The quoted uncertainties include the systematic error due to the uncertainty in the stellar mass (M*=0.980+/-0.062 M_{sun}_) The timings of the transits have an accuracy of 25s and are consistent with a uniform period, thus providing a baseline for future observations with the NASA Kepler satellite, whose field of view will include TrES-2.
- ID:
- ivo://CDS.VizieR/J/PASP/123/26
- Title:
- Time of Maxima for the SX Phe star XX Cyg
- Short Name:
- J/PASP/123/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- XX Cyg is a High Amplitude {delta} Scuti star which has been extensively studied because of its changing period. We present 64 new times of maxima which have been combined with 174 times of maxima from literature, in order to give an updated ephemeris and O-C plot for XX Cyg. Its period, currently found to be 0.134865117(3) days, is shown to be increasing continuously, which has lead to a new calculated value of (1/P)(dP/dt)=(1.33+/-0.09)10^-8^yr^-1^
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/2396
- Title:
- Time-series photometry of IC 348
- Short Name:
- J/MNRAS/462/2396
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present long-term photometric observations of the young open cluster IC 348 with a baseline time-scale of 2.4yr. Our study was conducted with several telescopes from the Young Exoplanet Transit Initiative (YETI) network in the Bessell R band to find periodic variability of young stars. We identified 87 stars in IC 348 to be periodically variable; 33 of them were unreported before. Additionally, we detected 61 periodic non-members of which 41 are new discoveries. Our wide field of view was the key to those numerous newly found variable stars. The distribution of rotation periods in IC 348 has always been of special interest. We investigate it further with our newly detected periods but we cannot find a statistically significant bimodality. We also report the detection of a close eclipsing binary in IC 348 composed of a low-mass stellar component (M>~0.09M_{sun}_) and a K0 pre-main sequence star (M~2.7M_{sun}_). Furthermore, we discovered three detached binaries among the background stars in our field of view and confirmed the period of a fourth one.
- ID:
- ivo://CDS.VizieR/J/PASP/133/H4201
- Title:
- Times of maxima for 23 delta Scuti stars
- Short Name:
- J/PASP/133/H4201
- Date:
- 17 Jan 2022 00:25:09
- Publisher:
- CDS
- Description:
- The multi-color CCD photometric study of 27 delta Scuti stars is presented. By using approximately three years of photometric observations, we obtained the times of maxima and magnitude changes during the observation time interval for each star. The ephemeris of our delta Scuti star was calculated based on the Markov Chain Monte Carlo (MCMC) method using the observed times of maxima and the period of star' oscillations. We used the Gaia EDR3 parallaxes to calculate the luminosities and also the absolute magnitudes of these delta Scuti stars. The fundamental physical parameters of all studied stars, such as mass and radius, were estimated. We determined the pulsation modes of the stars based on the pulsation constants. Moreover, the period-luminosity relation of delta Scuti stars was investigated and discussed. Then, by using a machine learning classification, new P-L relations for fundamental and overtone modes are presented.
- ID:
- ivo://CDS.VizieR/J/PASP/125/639
- Title:
- Times of Maxima for the SX Phe star BL Cam
- Short Name:
- J/PASP/125/639
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of 73 new times of maximum light for BL Cam were observed through the years 2005 to 2011, which are combined with 1392 times of maxima taken from literature. A more accurate period of 0.039097912(1) days was found, and an updated linear ephemeris is presented. This newly presented linear ephemeris was used to calculate revised O minus C values, which were fitted with a parabolic curve to measure the rate of change of the pulsation period, found to be (1/P)(dP/dt)=1.37+/-0.02x10^-7yr^-1. Although the parabolic fit has a physical interpretation, it is noted that a cubic more appropriately fits the behavior of the O minus C diagram.
- ID:
- ivo://CDS.VizieR/J/AJ/144/92
- Title:
- Times of maximum light for the SX Phe star XX Cyg
- Short Name:
- J/AJ/144/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Time-series photometric observations were made for the SX Phoenicis star XX Cyg between 2007 and 2011 at the Xinglong Station of National Astronomical Observatories of China. With the light curves derived from the new observations, we do not detect any secondary maximum in the descending portion of the light curves of XX Cyg, as reported in some previous work. Frequency analysis of the light curves confirms a fundamental frequency f_0_=7.4148cycles/day and up to 19 harmonics, 11 of which are newly detected. However, no secondary mode of pulsation is detected from the light curves. The O-C diagram, produced from 46 newly determined times of maximum light combined with those derived from the literature, reveals a continuous period increase with the rate of (1/P)(dP/dt)=1.19(13)x10^-8^/yr. Theoretical rates of period change due to the stellar evolution were calculated with a modeling code. The result shows that the observed rate of period change is fully consistent with period change caused by evolutionary behavior predicted by standard theoretical models.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A71
- Title:
- Times of minima for 1SWASP J234401.81-212229.1
- Short Name:
- J/A+A/558/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report our investigation of 1SWASP J234401.81-212229.1, a variable with a 18461.6s period. After identification in a 2011 search of the SuperWASP archive for main-sequence eclipsing binary candidates near the distribution's short-period limit of ~0.20d, it was measured to be undergoing rapid period decrease in our earlier work, though later observations supported a cyclic variation in period length. Spectroscopic data obtained in 2012 with the Southern African Large Telescope did not, however, support the interpretation of the object as a normal eclipsing binary. Here, we consider three possible explanations consistent with the data: a single-star oblique rotator model in which variability results from stable cool spots on opposite magnetic poles; a two-star model in which the secondary is a brown dwarf; and a three-star model involving a low-mass eclipsing binary in a hierarchical triple system. We conclude that the latter is the most likely model.
- ID:
- ivo://CDS.VizieR/J/ApJ/824/1
- Title:
- Timing data for the classical Cepheid l Car
- Short Name:
- J/ApJ/824/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The classical Cepheid l Carinae is an essential calibrator of the Cepheid Leavitt Law as a rare long-period Galactic Cepheid. Understanding the properties of this star will also constrain the physics and evolution of massive (M>=8M_{sun}_) Cepheids. The challenge, however, is precisely measuring the star's pulsation period and its rate of period change. The former is important for calibrating the Leavitt Law and the latter for stellar evolution modeling. In this work, we combine previous time-series observations spanning more than a century with new observations to remeasure the pulsation period and compute the rate of period change. We compare our new rate of period change with stellar evolution models to measure the properties of l Car, but find models and observations are, at best, marginally consistent. The results imply that l Car does not have significantly enhanced mass-loss rates like that measured for {delta} Cephei. We find that the mass of l Car is about 8-10M_{sun}_. We present Hubble Space Telescope Cosmic Origins Spectrograph observations that also differ from measurements for {delta} Cep and {beta} Dor. These measurements further add to the challenge of understanding the physics of Cepheids, but do hint at the possible relation between enhanced mass-loss and ultraviolet emission, perhaps both due to the strength of shocks propagating in the atmospheres of Cepheids.
