- ID:
- ivo://CDS.VizieR/J/ApJS/228/11
- Title:
- Time-dependent cooling in photoionized plasma
- Short Name:
- J/ApJS/228/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I explore the thermal evolution and ionization states in gas cooling from an initially hot state in the presence of external photoionizing radiation. I compute the equilibrium and nonequilibrium cooling efficiencies, heating rates, and ion fractions for low-density gas cooling while exposed to the ionizing metagalactic background radiation at various redshifts (z=0-3), for a range of temperatures (10^8^-10^4^K), densities (10^-7^-10^3^cm^-3^), and metallicities (10^-3^-2 times solar). The results indicate the existence of a threshold ionization parameter, above which the cooling efficiencies are very close to those in photoionization equilibrium (so that departures from equilibrium may be neglected), and below which the cooling efficiencies resemble those in collisional time-dependent gas cooling with no external radiation (and are thus independent of density).
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21192. Time minima of EP Aur
- ID:
- ivo://CDS.VizieR/J/other/NewA/35.48
- Title:
- Time minima of EP Aur
- Short Name:
- J/other/NewA/35.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new observations for the eclipsing binary EP Aurigae, which were performed by using three small telescopes in China from 2003 December to 2014 January. With the updated 2003 version of the Wilson-Devinney code, the photometric elements were deduced from three sets of light curves. Based on all available eclipsing times, the orbital period changes were investigated. It is discovered that the (O-C) curve may show an existence of light-time effect due to an unseen third body, which was weakly identified by the photometric solution. The modulated period and amplitude of the cyclic variation are P_3_=71.2(+/-8.0)yr and A=0.0101(+/-0.0008)day, respectively. In the co-planar orbit with the binary system, the mass of the third body is M_3_=0.18(+/-0.02)M_{sun}_. The photometric results imply that EP Aur is an Algol-type binary with a mass ratio of q=0.831(+/-0.004). Its primary component almost fills its Roche lobe. Therefore, EP Aur may consist of a normal main-sequence star and a cool Roche-lobe filling subgiant, which may be undergoing rapid mass transfer.
- 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^
21194. Time of minima of BX Peg
- ID:
- ivo://CDS.VizieR/J/other/NewA/41.17
- Title:
- Time of minima of BX Peg
- Short Name:
- J/other/NewA/41.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We presented BVRcIc light curves of BX Peg obtained by the Weihai Observatory 1.0m telescope of Shandong University. The W-D code was used to analyze the four color light curves, it is shown that BX Peg is a W-subtype shallow contact binary with a fill-out factor of f=14.6%. The asymmetric light curves were explained by a dark spot on the less massive hot component. A total of 328 times of minimum light were used to study the orbital period variation of BX Peg. We found that the orbital period of BX Peg was continuous decrease with a rate of dp/dt=-2.07x10^-7^d/yr superimposed on a cyclic oscillation with a period of 57.8yr. The secular period decrease should be caused by the angular momentum loss via magnetic stellar wind. The cyclic modulation is very likely to be produced by the light travel time effect due to a tertiary companion.
- ID:
- ivo://CDS.VizieR/J/other/JAVSO/38.183
- Title:
- Time of minima of eclipsing binaries
- Short Name:
- J/other/JAVSO/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper continues the publication of times of minima for eclipsing binary stars from observations reported to the AAVSO Eclipsing Binary section. Times of minima from observations made from September 2009 through February 2010 are presented.
21196. Time of minima of HD 181068
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/1656
- Title:
- Time of minima of HD 181068
- Short Name:
- J/MNRAS/428/1656
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 181068 is the brighter of the two known triply eclipsing hierarchical triple stars in the Kepler field. It has been continuously observed for more than 2yr with the Kepler space telescope. Of the nine quarters of the data, three have been obtained in short-cadence mode, that is one point per 58.9s. Here we analyse this unique data set to determine absolute physical parameters (most importantly the masses and radii) and full orbital configuration using a sophisticated novel approach. We measure eclipse timing variations (ETVs), which are then combined with the single-lined radial velocity measurements to yield masses in a manner equivalent to double-lined spectroscopic binaries. We have also developed a new light-curve synthesis code that is used to model the triple, mutual eclipses and the effects of the changing tidal field on the stellar surface and the relativistic Doppler beaming. By combining the stellar masses from the ETV study with the simultaneous light-curve analysis we determine the absolute radii of the three stars. Our results indicate that the close and the wide subsystems revolve in almost exactly coplanar and prograde orbits. The newly determined parameters draw a consistent picture of the system with such details that have been beyond reach before.
- ID:
- ivo://CDS.VizieR/J/AJ/162/114
- Title:
- Times & durations in Kepler-80 planetary system
- Short Name:
- J/AJ/162/114
- Date:
- 16 Mar 2022 00:10:21
- Publisher:
- CDS
- Description:
- Since the launch of the Kepler space telescope in 2009 and the subsequent K2 mission, hundreds of multiplanet systems have been discovered. The study of such systems, both as individual systems and as a population, leads to a better understanding of planetary formation and evolution. Kepler-80, a K dwarf hosting six super-Earths, was the first system known to have four planets in a chain of resonances, a repeated geometric configuration. Transiting planets in resonant chains can enable us to estimate not only the planets' orbits and sizes but also their masses. Since the original resonance analysis and TTV fitting of Kepler-80, a new planet has been discovered whose signal likely altered the measured masses of the other planets. Here, we determine masses and orbits for all six planets hosted by Kepler-80 by direct forward photodynamical modeling of the light curve of this system. We then explore the resonant behavior of the system. We find that the four middle planets are in a resonant chain, but that the outermost planet only dynamically interacts in ~14% of our solutions. We also find that the system and its dynamic behavior are consistent with in situ formation and compare our results to two other resonant chain systems, Kepler-60 and TRAPPIST-1.
- ID:
- ivo://CDS.VizieR/J/other/JAD/15.1
- Title:
- Time-series of 9 cataclysmic variables
- Short Name:
- J/other/JAD/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series photometry of nine cataclysmic variables: EI UMa, V844 Her, V751 Cyg, V516 Cyg, GZ Cnc, TY Psc, V1315 Aql, ASAS J002511+1217.2, V1315 Aql and LN UMa. The observations were conducted at various observatories, covering 170 hours and comprising 7850 data points in total. For the majority of targets we confirm previously reported periodicities and for some of them we give, for the first time through photometry, their underlying spectroscopic orbital period. For those dwarf-nova systems which we observed during both quiescence and outburst, the increase in brightness was accompanied by a decrease in the level of flickering. For the eclipsing system V1315 Aql we have covered 9 eclipses, and obtained a refined orbital ephemeris. We find that, during its long baseline of observations, no change in the orbital period of this system has occurred. V1315 Aql also shows eclipses of variable depth.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A106
- Title:
- Time-series photometry of 2012 DA14
- Short Name:
- J/A+A/559/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The object 2012 DA14 is a near-Earth asteroid with a size of several tens of meters. It had approached closely the Earth on 15 February 2013 UT, providing an opportunity for precise measurements of this tiny asteroid. The solar phase angle of 2012 DA14 had varied widely around its closest approach but was almost constant during the following night. We performed time-series photometric observations on those two nights to determine the rotational properties and phase effect. The observations were carried out using the 0.55-m telescope at Saitama University, Japan. The R-band images were obtained continuously over a 2h period at the closest approach and for about 5h on the next night.
- 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.
