- 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_).
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- 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).
- 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.
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/156/216
- Title:
- Differential photometry & RVs of HATS-59
- Short Name:
- J/AJ/156/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first discovery of a multi-planetary system by the HATSouth network, HATS-59b,c, a planetary system with an inner transiting hot Jupiter and an outer cold massive giant planet, which was detected via radial velocity. The inner transiting planet, HATS-59b, is on an eccentric orbit with e=0.129+/-0.049, orbiting a V=13.951+/-0.030 mag solar-like star (M_*_=1.038+/-0.039 M_{sun}_ and R_*_=1.036+/-0.067 R_{sun}_) with a period of 5.416081+/-0.000016 days. The outer companion, HATS-59c is on a circular orbit with msini=12.70+/-0.87 M_J_ and a period of 1422+/-14 days. The inner planet has a mass of 0.806+/-0.069 M_J_ and a radius of 1.126+/-0.077 R_J_, yielding a density of 0.70+/-0.16 g/cm^3^. Unlike most planetary systems that include only a single hot Jupiter, HATS-59b,c includes, in addition to the transiting hot Jupiter, a massive outer companion. The architecture of this system is valuable for understanding planet migration.
- ID:
- ivo://CDS.VizieR/J/A+A/469/285
- Title:
- Differential Stroemgren photometry of U Oph
- Short Name:
- J/A+A/469/285
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to determine absolute dimensions for the mid B-type eclipsing binary U Ophiuchi and compare the inferred ages and chemical compositions to those of other binary stars with masses near 5M_{sun}_. We determine masses, radii, logg, logT_eff_, and luminosities for the stars in U Oph from new radial velocities and uvby light curves. By improving the Wilson-Devinney code, we also derive precise apsidal-motion and light-time orbits of this triple system, using 353 times of minimum over 120 years. Finally, we compare the data for U Oph and similar systems with the predictions of stellar models.
- ID:
- ivo://CDS.VizieR/J/A+A/480/187
- Title:
- Differential Stromgren photometry of 15 And
- Short Name:
- J/A+A/480/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {lambda} Bootis stars are a chemically peculiar subgroup of main sequence A/F stars. Several of these fall into the instability strip of the {delta} Scuti stars and the whole spectroscopic group shows a high incidence of pulsational variability. We investigated the pulsational behaviour of the {lambda} Bootis star 15 And (HD 221756) to determine as many intrinsic mode frequencies as possible for asteroseismic applications.
- ID:
- ivo://CDS.VizieR/J/A+A/456/261
- Title:
- Differential uvby photometry of HD 239276
- Short Name:
- J/A+A/456/261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The variability of HD 239276 was suspected photometrically nearly twenty years ago, but was confirmed with new observations obtained in 2001 during a two-site photometric campaign carried out from Spain, in uvby{beta} Stroemgren-Crawford photometry, and China, using the Johnson V filter. Two low-dispersion spectra were also collected. The results establish this star as a new multiperiodic gamma Dor-type pulsator with deficiency in metallicity.
