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1621. Differential photometry of HD 8801
ID:
ivo://CDS.VizieR/J/AJ/129/2026
Title:
Differential photometry of HD 8801
Short Name:
J/AJ/129/2026
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have discovered the first example of a star pulsating intrinsically with both {gamma} Doradus and {delta} Scuti frequencies. HD 8801 is an Am metallic-line star that appears to be single. Since the vast majority of Am stars are members of binary systems with periods less than 1000 days and also do not pulsate, HD 8801 possesses a very unusual, if not unique, combination of physical properties. Our photometry, acquired with an automatic telescope at Fairborn Observatory, resolves six independent pulsation periods between 0.048 and 0.404 days. The two longest periods lie within the range of {gamma} Dor variables, while the four shorter periods are within the range of {delta} Sct stars.
1622. Differential photometry of MML 53
ID:
ivo://CDS.VizieR/J/A+A/623/A23
Title:
Differential photometry of MML 53
Short Name:
J/A+A/623/A23
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binaryMML53 (with P_EB_=2.097892d), and for the first time, confirm the bound-nature of the third star (in a P_3_~9yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880+/-100K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M1=1.0400+/-0.0067M_{sun}_ and M2=0.8907+/-0.0058M_{sun}_), their radii within 4.5% (R1=1.283+/-0.043R_{sun}_ and R2=1.107+/-0.049R_{sun}_), and the temperature of the secondary star (T_eff,2_=4379+/-100K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7M_{sun}_ (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16+/-2Myr). At this age, the tightening of the MML53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars' evolution. The eclipsing components of MML53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04M_{sun}_ primary star of MML53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsing stars of MML53 are found to be larger but not cooler than predicted by non-magnetic models, it is not clear what is the mechanism that is causing the radius inflation given that activity, spots and/or magnetic fields slowing their contraction, require the inflated stars to be cooler to remain in thermal equilibrium.
1623. Differential photometry of the EB* HATS551-027
ID:
ivo://CDS.VizieR/J/MNRAS/451/2263
Title:
Differential photometry of the EB* HATS551-027
Short Name:
J/MNRAS/451/2263
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery and characterization of a new M-dwarf binary, with component masses and radii of M_1_=0.244_-0.003_^+0.003^M_{sun}_, R_1_=0.261_-0.009_^+0.006^R_{sun}_, M_2_=0.179_-0.001_^+0.002^M_{sun}_, R_2_=0.218_-0.011_^+0.007^R_{sun}_, and orbital period of ~4.1 d. The M-dwarf binary HATS551-027 (LP 837-20) was identified as an eclipsing binary by the HATSouth survey, and characterized by a series of high-precision photometric observations of the eclipse events, and spectroscopic determinations of the atmospheric parameters and radial velocity orbits. HATS551-027 is one of few systems with both stellar components lying in the fully convective regime of very low mass stars, and can serve as a test for stellar interior models. The radius of HATS551-027A is consistent with models to 1{sigma}, whilst HATS551-027B is inflated by 9 percent at 2{sigma} significance. We measure the effective temperatures for the two stellar components to be T_eff,1_=3190+/-100K and T_eff,2_=2990+/-110K; both are slightly cooler than theoretical models predict, but consistent with other M-dwarfs of similar masses that have previously been studied. We also measure significant H{alpha} emission from both components of the binary system, and discuss this in the context of the correlation between stellar activity and the discrepancies between the observed and model temperatures.
1624. Differential photometry of the F-subgiant HAT-P-67
ID:
ivo://CDS.VizieR/J/AJ/153/211
Title:
Differential photometry of the F-subgiant HAT-P-67
Short Name:
J/AJ/153/211
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of HAT-P-67b, which is a hot-Saturn transiting a rapidly rotating F-subgiant. HAT-P-67b has a radius of R_p_=2.085_-0.071_^+0.096^ R_J_, and orbites a M_*_=1.642_-0.072_^+0.155^ M_{sun}_, R_*_=2.546_-0.084_^+0.099^ R_{sun}_ host star in a ~4.81 day period orbit. We place an upper limit on the mass of the planet via radial velocity measurements to be M_p_<0.59 M_J_, and a lower limit of >0.056 M_J_ by limitations on Roche lobe overflow. Despite being a subgiant, the host star still exhibits relatively rapid rotation, with a projected rotational velocity of vsini_*_=35.8+/-1.1 km/s, which makes it difficult to precisely determine the mass of the planet using radial velocities. We validated HAT-P-67b via two Doppler tomographic detections of the planetary transit, which eliminate potential eclipsing binary blend scenarios. The Doppler tomographic observations also confirm that HAT-P-67b has an orbit that is aligned to within 12{deg}, in projection, with the spin of its host star. HAT-P-67b receives strong UV irradiation and is among one of the lowest density planets known, which makes it a good candidate for future UV transit observations in the search for an extended hydrogen exosphere.
1625. Differential photometry of the K dwarf HATS-7
ID:
ivo://CDS.VizieR/J/ApJ/813/111
Title:
Differential photometry of the K dwarf HATS-7
Short Name:
J/ApJ/813/111
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery by the HATSouth network of HATS-7b, a transiting Super-Neptune with a mass of 0.120+/-0.012M_J_, a radius of 0.563_-0.034_^+0.046^R_J_, and an orbital period of 3.1853 days. The host star is a moderately bright (V=13.340+/-0.010mag, Ks=10.976+/-0.026mag) K dwarf star with a mass of 0.849+/-0.027M_{sun}_, a radius of 0.815_-0.035_^+0.049^R_{sun}_, and a metallicity of [Fe/H]=+0.250+/-0.080. The star is photometrically quiet to within the precision of the HATSouth measurements, has low RV jitter, and shows no evidence for chromospheric activity in its spectrum. HATS-7b is the second smallest radius planet discovered by a wide-field ground-based transit survey, and one of only a handful of Neptune-size planets with mass and radius determined to 10% precision. Theoretical modeling of HATS-7b yields a hydrogen-helium fraction of 18+/-4% (rock-iron core and H_2_-He envelope), or 9+/-4% (ice core and H_2_-He envelope), i.e., it has a composition broadly similar to that of Uranus and Neptune, and very different from that of Saturn, which has 75% of its mass in H_2_-He. Based on a sample of transiting exoplanets with accurately (<20%) determined parameters, we establish approximate power-law relations for the envelopes of the mass-density distribution of exoplanets. HATS-7b, which, together with the recently discovered HATS-8b, is one of the first two transiting super-Neptunes discovered in the Southern sky, is a prime target for additional follow-up observations with Southern hemisphere facilities to characterize the atmospheres of Super-Neptunes (which we define as objects with mass greater than that of Neptune, and smaller than halfway between that of Neptune and Saturn, i.e., 0.054M_J_<M_p_<0.18M_J_).
1626. Differential photometry of the SB* BD+20 307
ID:
ivo://CDS.VizieR/J/ApJ/688/1345
Title:
Differential photometry of the SB* BD+20 307
Short Name:
J/ApJ/688/1345
Date:
21 Oct 2021
Publisher:
CDS
Description:
Field star BD+20 307 is the dustiest known main-sequence star, based on the fraction of its bolometric luminosity, ~4%, that is emitted at infrared wavelengths. The particles that carry this large infrared luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this age using the Chandra X-Ray Observatory to measure the X-ray flux of BD+20 307 in conjunction with extensive photometric and spectroscopic monitoring observations from Fairborn Observatory. However, the recent realization that BD+20 307 is a short-period, double-line, spectroscopic binary whose components have very different lithium abundances vitiates standard methods of age determination. We find the system to be metal-poor; this, combined with its measured lithium abundances, indicates that BD+20 307 may be several to many Gyr old. BD+20 307 affords astronomy a rare peek into a mature planetary system in orbit around a close binary star (because such systems are not amenable to study by the precision radial velocity technique).
1627. Differential photometry of V1061 Cyg
ID:
ivo://CDS.VizieR/J/ApJ/640/1018
Title:
Differential photometry of V1061 Cyg
Short Name:
J/ApJ/640/1018
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopic and photometric observations of the eclipsing system V1061 Cyg (P=2.35days). A third star is visible in the spectrum, and the system is a hierarchical triple.
1628. Differential photometry of WX Cet
ID:
ivo://CDS.VizieR/J/A+A/463/1053
Title:
Differential photometry of WX Cet
Short Name:
J/A+A/463/1053
Date:
21 Oct 2021
Publisher:
CDS
Description:
WX Cet is a dwarf nova with rare outbursts of large amplitude. We compile the available data of WX Cet, compare the results with other SU UMa stars, and discuss our findings in the context of current theories of superhumps and superoutbursts to progress with our understanding of SU UMa stars.
1629. Differential photometry & radial velocities of HATS-70
ID:
ivo://CDS.VizieR/J/AJ/157/31
Title:
Differential photometry & radial velocities of HATS-70
Short Name:
J/AJ/157/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of HATS-70b, a transiting brown dwarf at the deuterium burning limit. HATS-70b has a mass of M_p_=12.9_-1.6_^+1.8^ M_Jup_ and a radius of R_p_=1.384_-0.074_^+0.079^ R_Jup_, residing in a close-in orbit with a period of 1.89 days. The host star is a M_*_=1.78+/-0.12 M_{sun}_ A star rotating at vsinI_*_=40.61_-0.35_^+0.32^ km/s, enabling us to characterize the spectroscopic transit of the brown dwarf via Doppler tomography. We find that HATS-70b, like other massive planets and brown dwarfs previously sampled, orbits in a low projected-obliquity orbit with {lambda}=8.9_-4.5_^+5.6o^. The low obliquities of these systems is surprising given all brown dwarf and massive planets with obliquities measured orbit stars hotter than the Kraft break. This trend is tentatively inconsistent with dynamically chaotic migration for systems with massive companions, though the stronger tidal influence of these companions makes it difficult to draw conclusions on the primordial obliquity distribution of this population. We also introduce a modeling scheme for planets around rapidly rotating stars, accounting for the influence of gravity darkening on the derived stellar and planetary parameters.
1630. Differential photometry & RVs of HAT-P-69 & HAT-P-70
ID:
ivo://CDS.VizieR/J/AJ/158/141
Title:
Differential photometry & RVs of HAT-P-69 & HAT-P-70
Short Name:
J/AJ/158/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the Transiting Exoplanet Survey Satellite. HAT-P-69 b has a mass of 3.58_-0.58_^+0.58^ M_Jup_ and a radius of 1.676_-0.033_^+0.051^ R_Jup_ and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of 1.87_-0.10_^+0.15^ R_Jup_ and a mass constraint of <6.78 (3{sigma}) M_Jup_ and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47126 main-sequence stars brighter than T_mag_=10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41+/-0.10% within this sample, consistent with the rate measured by Kepler for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71+/-0.31% for G stars, 0.43+/-0.15% for F stars, and 0.26+/-0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass.