- 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).
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Search Results
- 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/AJ/143/70
- Title:
- Differential reddening in Milky Way globulars
- Short Name:
- J/AJ/143/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extensive photometric studies of the globular clusters located toward the center of the Milky Way have been historically neglected. The presence of patchy differential reddening in front of these clusters has proven to be a significant obstacle to their detailed study. We present here a well defined and reasonably homogeneous photometric database for 25 of the brightest Galactic globular clusters located in the direction of the inner Galaxy. These data were obtained in the B, V, and I bands using the Magellan 6.5m Telescope and the Hubble Space Telescope. A new technique is extensively used in this paper to map the differential reddening in the individual cluster fields, and to produce cleaner, dereddened color-magnitude diagrams for all the clusters in the database. Subsequent papers will detail the astrophysical analysis of the cluster populations, and the properties of the obscuring material along the clusters' lines of sight.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A43
- Title:
- Differential rotation in solar-like stars
- Short Name:
- J/A+A/591/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surface differential rotation (SDR) plays a key role in dynamo models and determines a lower limit on the accuracy of stellar rotation period measurements. SDR estimates are therefore essential to constrain theoretical models and infer realistic rotation period uncertainties. We measure a lower limit to SDR in a sample of solar-like stars belonging to young loose stellar associations with the aim of investigating how SDR depends on global stellar parameters in the age range (4-95Myr). The rotation period of a solar-like star can be recovered by analyzing the flux modulation caused by dark spots and stellar rotation. The SDR and the latitude migration of dark-spots induce a modulation of the detected rotation period. We employed long-term photometry to measure the amplitude of such a modulation and to compute the quantity {Delta}{Omega}_phot_=2{pi}/P_min_-2{pi}/P_max_ that is a lower limit to SDR. We find that {Delta}{Omega}_phot_ increases with the stellar effective temperature and with the global convective turn-over timescale tau_c_, which is the characteristic time for the rise of a convective element through the stellar convection zone. We find that {Delta}{Omega}_phot_ is proportional to T_eff_^2.18+/-0.65^ in stars recently settled on the ZAMS. This power law is less steep than those found by previous authors, but closest to recent theoretical models. We investigate how {Delta}{Omega}_phot_ changes in time in a 1M_{sun}_ star. We find that {Delta}{Omega}_phot_ steeply increases between 4 and 30Myr and that it is almost constant between 30 and 95Myr. We find also that the relative shear increases with the Rossby number Ro. Although our results are qualitatively in agreement with hydrodynamical mean-field models, our measurements are systematically higher than the values predicted by these models. The discrepancy between {Delta}{Omega}_phot_ measurements and theoretical models is particularly large in stars with periods between 0.7 and 2d. Such a discrepancy, together with the anomalous SDR measured by other authors for HD 171488 (rotating in 1.31d), suggests that the rotation period could influence SDR more than predicted by the models.
- 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.