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3491. Light curve of T Pyx from 1890 to 2011
ID:
ivo://CDS.VizieR/J/ApJ/773/55
Title:
Light curve of T Pyx from 1890 to 2011
Short Name:
J/ApJ/773/55
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery by M. Linnolt on JD 2455665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9mag/day, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/dot{P}=+313000yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950+/-0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5)x10^-7^M_{sun}_/yr. We report 6116 magnitudes between 1890 and 2011, for an average B=15.59+/-0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f_{nu}_{prop.to}{nu}^1.0^, although the narrow ultraviolet region has a tilt with a fit of f_{nu}_{prop.to}{nu}^1/3^.
3492. Light curve of V794 Aql over 1990-2012
ID:
ivo://CDS.VizieR/J/AJ/147/10
Title:
Light curve of V794 Aql over 1990-2012
Short Name:
J/AJ/147/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 1990-2012 light curve of the nova-like (NL) cataclysmic variable V794 Aql is studied in order to characterize and better understand the transitions to and from the faint state, and the variations within the bright state. Investigations of earlier portions of this data had concluded that the transitions to the low state were much slower than the rapid recovery, giving a sawtoothed appearance to the light curve. This behavior differs from that of most other VY Scl stars, which led to an interpretation of the large amplitude sawtooths as being due to an accretion disk (AD) instability. However, more recent photometry strongly suggests that the bright state itself has transitions of 1-1.5mag, and that earlier studies had intermixed these bright state variations with the transitions to the low state. These newly recognized variations within the bright state sometimes appear as small outbursts (OBs) with typical amplitudes of 0.5-1.5mag and spacings of ~15-50days. The rise times of the OBs are 2-3 times faster than the decline times. We argue that the V794 Aql bright state variations are due to AD behavior similar to that seen in dwarf novae, but with varying degrees of stability. Similar regular small OBs have also been reported in other NL CVs, which we compare with V794 Aql. The true deep low states in V794 Aql appear to be normal, having transition speeds and shapes very similar to the transitions in other VY Scl stars.
3493. Light curve of V945 Cen in Geneva photometry
ID:
ivo://CDS.VizieR/J/A+A/520/A73
Title:
Light curve of V945 Cen in Geneva photometry
Short Name:
J/A+A/520/A73
Date:
21 Oct 2021
Publisher:
CDS
Description:
A detailed analysis of multicolour Geneva photometry and high-resolution echelle spectroscopy of the B8.5V star V945 Cen (HD 112409, V=5.2mag) whose short-term periodic variability was first detected from the HIPPARCOS data, led to the finding that the object is an ellipsoidal variable and a close double-lined spectroscopic binary with a 0.6496d orbital period and a circular orbit. The components have spectral types B7 and B8.5 and are both main-sequence objects. The system is detached but close to a contact configuration and is observed at an inclination of ~23-24{deg}. A notable finding is that the optical spectrum also contains a third system of spectral lines corresponding to a late B spectral type that remained stationary during the 5 days of spectral observations. From several independent lines of reasoning, we tentatively conclude that the third spectrum belongs to a real third body in the system. However, the possibility that it instead originates in circumbinary gas cannot be excluded completely, and additional spectral and interferometric observations are required to help us determine its origin conclusively.
3494. Light-curve parameters from the SNLS
ID:
ivo://CDS.VizieR/J/ApJS/192/1
Title:
Light-curve parameters from the SNLS
Short Name:
J/ApJS/192/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We combine high-redshift Type Ia supernovae from the first three years of the Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample of 472 SNe (123 low-z, 93 SDSS, 242 SNLS, and 14 Hubble Space Telescope). SN data alone require cosmic acceleration at >99.999% confidence, including systematic effects. For the dark energy equation of state parameter (assumed constant out to at least z=1.4) in a flat universe, we find w=-0.91^+0.16^_-0.20_(stat)^+0.07^_-0.14_(sys) from SNe only, consistent with a cosmological constant. Our fits include a correction for the recently discovered relationship between host-galaxy mass and SN absolute brightness. We pay particular attention to systematic uncertainties, characterizing them using a systematic covariance matrix that incorporates the redshift dependence of these effects, as well as the shape-luminosity and color-luminosity relationships. Unlike previous work, we include the effects of systematic terms on the empirical light-curve models. The total systematic uncertainty is dominated by calibration terms. We describe how the systematic uncertainties can be reduced with soon to be available improved nearby and intermediate-redshift samples, particularly those calibrated onto USNO/SDSS-like systems.
3495. Light curve & radial velocities for TOI-172
ID:
ivo://CDS.VizieR/J/AJ/157/191
Title:
Light curve & radial velocities for TOI-172
Short Name:
J/AJ/157/191
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of only the TESS full frame images, because the host star was not chosen as a two-minute cadence target. From a global analysis of the TESS photometry and follow-up observations carried out by the TESS Follow-up Observing Program Working Group, TOI-172 (TIC 29857954) is a slightly evolved star with an effective temperature of T_eff_=5645+/-50 K, a mass of M_*_=1.128_-0.061_^+0.065^ M_{sun}_, radius of R_*_=1.777_-0.044_^+0.047^ R_{sun}_, a surface gravity of log g_*_=3.993_-0.028_^+0.027^, and an age of 7.4_-1.5_^+1.6^ Gyr. Its planetary companion (TOI-172 b) has a radius of R_P_=0.965_-0.029_^+0.032^ R_J_, a mass of M_P_=5.42_-0.20_^+0.22^ M_J_, and is on an eccentric orbit (e=0.3806_-0.0090_^+0.0093^). TOI-172 b is one of the few known massive giant planets on a highly eccentric short-period orbit. Future study of the atmosphere of this planet and its system architecture offer opportunities to understand the formation and evolution of similar systems.
3496. Light curves and eclipse times of HW Vir
ID:
ivo://CDS.VizieR/J/MNRAS/506/2122
Title:
Light curves and eclipse times of HW Vir
Short Name:
J/MNRAS/506/2122
Date:
17 Jan 2022 00:24:15
Publisher:
CDS
Description:
A growing number of eclipsing binary systems of the HW Virginis (HW Vir) kind (i.e. composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called eclipse time variations (ETVs). Their physical origin is not yet known with certainty: While some ETVs have been claimed to arise from dynamical perturbations due to the presence of circumbinary planetary companions, other authors suggest that the Applegate effect or other unknown stellar mechanisms could be responsible for them. In this work, we present 28 unpublished high-precision light curves of one of the most controversial of these systems, the prototype HW Vir. We homogeneously analysed the new eclipse timings together with historical data obtained between 1983 and 2012, demonstrating that the planetary models previously claimed do not fit the new photometric data, besides being dynamically unstable. In an effort to find a new model able to fit all the available data, we developed a new approach based on a global-search genetic algorithm and eventually found two new distinct families of solutions that fit the observed timings very well, yet dynamically unstable at the 10^5^-yr time-scale. This serves as a cautionary tale on the existence of formal solutions that apparently explain ETVs but are not physically meaningful, and on the need of carefully testing their stability. On the other hand, our data confirm the presence of an ETV on HW Vir that known stellar mechanisms are unable to explain, pushing towards further observing and modeling efforts.
3497. Light curves and RVs of WASP-174
ID:
ivo://CDS.VizieR/J/A+A/633/A30
Title:
Light curves and RVs of WASP-174
Short Name:
J/A+A/633/A30
Date:
21 Oct 2021
Publisher:
CDS
Description:
The transiting exoplanetary system WASP-174 was reported to be composed by a main-sequence F star and a giant planet, WASP-174b. However only an upper limit was placed on the planet mass, and a highly uncertain planetary radius was determined. We aim to better characterise both the star and the planet and precisely measure their orbital and physical parameters. In order to constrain the mass of the planet, we obtained new measurements of the radial velocity of the star and joined them with those from the discovery paper. Photometric data Q1 from the HATSouth survey and new multi-band, high-quality (precision reached up to 0.37mmag) photometric follow-up observations of transit events were acquired and analysed for getting accurate photometric parameters. We fit the model to all the observations, including data from the TESS space telescope, in two different modes: incorporating the stellar isochrones into the fit, and using an empirical method to get the stellar parameters. The two modes resulted to be consistent with each other. We confirm the grazing nature of the WASP-174b transits, which is also corroborated by simultaneously observing the transit through four optical bands and noting how the transit depth changes due to the limb-darkening effect. We estimate that 76% of the disk of the planet actually eclipses the parent star at mid-transit of its transit events. We find that WASP-174b is a highly-inflated hot giant planet with a mass of 0.330M_Jup_ and a radius of 1.435R_Jup_, and is therefore a good target for transmission-spectroscopy observations. With a density of 0.135g/cm^3^, it is amongst the lowest-density planets ever discovered with precisely measured mass and radius.
3498. Light curve segments of 22 host stars with TESS
ID:
ivo://CDS.VizieR/J/AJ/160/155
Title:
Light curve segments of 22 host stars with TESS
Short Name:
J/AJ/160/155
Date:
10 Dec 2021
Publisher:
CDS
Description:
We present a systematic phase curve analysis of known transiting systems observed by the Transiting Exoplanet Survey Satellite (TESS) during year one of the primary mission. Using theoretical predictions for the amplitude of the planetary longitudinal atmospheric brightness modulation, stellar ellipsoidal distortion and Doppler boosting, as well as brightness considerations to select targets with likely detectable signals, we applied a uniform data processing and light-curve modeling framework to fit the full-orbit phase curves of 22 transiting systems with planet-mass or brown dwarf companions, including previously published systems. Statistically significant secondary eclipse depths and/or atmospheric brightness modulation amplitudes were measured for HIP65A, WASP-18, WASP-19, WASP-72, WASP-100, WASP-111, WASP-121, and WASP-122/KELT-14. For WASP-100b, we found marginal evidence that the brightest region of the atmosphere is shifted eastward away from the substellar point. We detected significant ellipsoidal distortion signals in the light curves of HIP65A, TOI-503, WASP-18, and WASP-30, with HIP65A, TOI-503 and WASP-18 also exhibiting Doppler boosting. The measured amplitudes of these signals agree with the predictions of theoretical models. Combining the optical secondary eclipse depths with previously published Spitzer 3.6 and 4.5{mu}m measurements, we derived dayside brightness temperatures and visible-light geometric albedos for a subset of the analyzed systems. We also calculated updated transit ephemerides combining the transit timings from the TESS light curves with previous literature values.
3499. Light curves 0f 6 MC eclipsing binaries
ID:
ivo://CDS.VizieR/J/A+A/609/A46
Title:
Light curves 0f 6 MC eclipsing binaries
Short Name:
J/A+A/609/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim to present a novel method to determine compact triples using publicly available photometric data from large surveys. Here we apply it to eclipsing binaries (EBs) in Magellanic Clouds from OGLE III database. Our tool consists of identifying the cases where the orbital plane of EB evolves in accord with expectations from the interaction with a third star. We analyzed light curves (LCs) of 26121 LMC and 6138 SMC EBs with the goal to identify those for which the orbital inclination varies in time. Archival LCs of the selected systems, when complemented by our own observations with Danish 1.54-m telescope, were thoroughly analyzed using the PHOEBE program. This provided physical parameters of components of each system. Time dependence of the EB inclination was described using the theory of orbital-plane precession. By observing the parameter-dependence of the precession rate, we were able to constrain the third companion mass and its orbital period around EB.
3500. Light curves for five M-dwarf stars
ID:
ivo://CDS.VizieR/J/ApJ/701/764
Title:
Light curves for five M-dwarf stars
Short Name:
J/ApJ/701/764
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have derived masses and radii for both components in five short-period single-lined eclipsing binary stars discovered by the TrES wide-angle photometric survey for transiting planets. All these systems consist of a visible F-star primary and an unseen M-star secondary (M_A_>=0.8M_{sun}_, M_B_<=0.45M_{sun}_). The spectroscopic orbital solution combined with a high-precision transit light curve for each system gives sufficient information to calculate the density of the primary star and the surface gravity of the secondary. The masses of the primary stars were obtained using stellar evolution models, which requires accurate determinations of metallicities and effective temperatures.