- ID:
- ivo://CDS.VizieR/J/AJ/155/112
- Title:
- Radial velocities & light curves for HATS-43-HATS-46
- Short Name:
- J/AJ/155/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four short-period extrasolar planets transiting moderately bright stars from photometric measurements of the HATSouth network coupled to additional spectroscopic and photometric follow-up observations. While the planet masses range from 0.26 to 0.90 M_J_, the radii are all approximately a Jupiter radii, resulting in a wide range of bulk densities. The orbital period of the planets ranges from 2.7 days to 4.7 days, with HATS-43b having an orbit that appears to be marginally non-circular (e=0.173+/-0.089). HATS-44 is notable for having a high metallicity ([Fe/H]=0.320+/-0.071). The host stars spectral types range from late F to early K, and all of them are moderately bright (13.3<V<14.4), allowing the execution of future detailed follow-up observations. HATS-43b and HATS-46b, with expected transmission signals of 2350 ppm and 1500 ppm, respectively, are particularly well suited targets for atmospheric characterization via transmission spectroscopy.
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- ID:
- ivo://CDS.VizieR/J/A+A/596/A116
- Title:
- Radial velocities of K-M dwarfs
- Short Name:
- J/A+A/596/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to present complete radial-velocity data for the spectroscopically selected McCormick (MCC) sample of nearby K-M dwarfs and, based on these data, to determine the space-velocity distributions of late-type stars in the solar neighborhood.
- ID:
- ivo://CDS.VizieR/J/AJ/160/3
- Title:
- Radial velocities of M-dwarf LTT 3780 with HARPS
- Short Name:
- J/AJ/160/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the confirmation of two new planets transiting the nearby mid-M dwarf LTT3780 (TIC36724087, TOI-732, V=13.07, Ks=8.204, Rs=0.374R{sun}, Ms=0.401 M{sun}, d=22pc). The two planet candidates are identified in a single Transiting Exoplanet Survey Satellite sector and validated with reconnaissance spectroscopy, ground-based photometric follow-up, and high-resolution imaging. With measured orbital periods of P_b_=0.77, P_c_=12.25days and sizes r_p,b_=1.33{+/-}0.07, r_p,c_=2.30{+/-}0.16R{earth}, the two planets span the radius valley in period-radius space around low-mass stars, thus making the system a laboratory to test competing theories of the emergence of the radius valley in that stellar mass regime. By combining 63 precise radial velocity measurements from the High Accuracy Radial velocity Planet Searcher (HARPS) and HARPS-N, we measure planet masses of m_p,b_=2.62_-0.46_^+0.48^ and m_p,c_=8.6_-1.3_^+1.6^M{earth}, which indicates that LTT3780b has a bulk composition consistent with being Earth-like, while LTT3780c likely hosts an extended H/He envelope. We show that the recovered planetary masses are consistent with predictions from both photoevaporation and core-powered mass-loss models. The brightness and small size of LTT3780, along with the measured planetary parameters, render LTT3780b and c as accessible targets for atmospheric characterization of planets within the same planetary system and spanning the radius valley.
- ID:
- ivo://CDS.VizieR/J/AJ/161/106
- Title:
- Radial velocities of 12 Psc and HD 159062
- Short Name:
- J/AJ/161/106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of a white dwarf companion to the G1 V star 12Psc found as part of a Keck adaptive optics imaging survey of long-term accelerating stars from the McDonald Observatory Planet Search Program. Twenty years of precise radial-velocity monitoring of 12Psc with the Tull Spectrograph at the Harlan J. Smith telescope reveals a moderate radial acceleration (~10m/s/yr), which together with relative astrometry from Keck/NIRC2 and the astrometric acceleration between Hipparcos and Gaia DR2 yields a dynamical mass of M_B_=0.605_-0.022_^+0.021^M{sun} for 12PscB, a semimajor axis of 40_-4_^+2^au, and an eccentricity of 0.84{+/-}0.08. We also report an updated orbital fit of the white dwarf companion to the metal-poor (but barium-rich) G9 V dwarf HD159062 based on new radial velocity observations from the High-Resolution Spectrograph at the Hobby-Eberly Telescope and astrometry from Keck/NIRC2. A joint fit of the available relative astrometry, radial velocities, and tangential astrometric acceleration yields a dynamical mass of M_B_=0.609_-0.011_^+0.010^M{sun} for HD159062B, a semimajor axis of 60_-7_^+5^au, and preference for circular orbits (e<0.42 at 95% confidence). 12PscB and HD159062B join a small list of resolved Sirius-like benchmark white dwarfs with precise dynamical mass measurements which serve as valuable tests of white dwarf mass-radius cooling models and probes of AGB wind accretion onto their main-sequence companions.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/29
- Title:
- Radial velocities of TOI-1728 with HPF
- Short Name:
- J/ApJ/899/29
- Date:
- 14 Mar 2022 09:03:00
- Publisher:
- CDS
- Description:
- We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an old, inactive M0 star with Teff=3980_-32_^+31^K, which hosts a transiting super-Neptune at an orbital period of ~3.49days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of 5.05_-0.17_^+0.16^ R{Earth}, mass 26.78_-5.13_^+5.43^M{Earth}, and eccentricity 0.057_-0.039_^+0.054^. We estimate the stellar properties, and perform a search for He 10830{AA} absorption during the transit of this planet and claim a null detection with an upper limit of 1.1% with 90% confidence. A deeper level of He 10830{AA} absorption has been detected in the planet atmosphere of GJ3470b, a comparable gaseous planet. TOI-1728b is the largest super-Neptune-the intermediate subclass of planets between Neptune and the more massive gas-giant planets-discovered around an M-dwarf. With its relatively large mass and radius, TOI-1728 represents a valuable data point in the M-dwarf exoplanet mass-radius diagram, bridging the gap between the lighter Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. With a low bulk density of 1.14_-0.24_^+0.26^g/cm^3^, and orbiting a bright host star (J~9.6, V~12.4), TOI-1728b is also a promising candidate for transmission spectroscopy both from the ground and from space, which can be used to constrain planet formation and evolutionary models.
- ID:
- ivo://CDS.VizieR/J/AJ/129/2294
- Title:
- Radial velocities of weak-lines T Tauri stars
- Short Name:
- J/AJ/129/2294
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To search for thermal emission from substellar companions, we have obtained Z-band images of 15 weak-lined T Tauri stars in the Taurus-Auriga and Ophiuchus star-forming regions using the Planetary Camera 2 on the Hubble Space Telescope. To complement the imaging program, extensive spectroscopic observations were obtained with the Center for Astrophysics Digital Speedometers.
- ID:
- ivo://CDS.VizieR/J/AJ/155/192
- Title:
- Radial velocities & photometry of AD Leonis & GJ 674
- Short Name:
- J/AJ/155/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days, as well as photometric signals: (1) a short-period signal, which is similar to the radial velocity signal, albeit with considerable variability; and (2) a long-term activity cycle of 4070+/-120 days. We examine the short-term photometric signal in the available All-Sky Automated Survey and Microvariability and Oscillations of STars (MOST) photometry and find that the signal is not consistently present and varies considerably as a function of time. This signal undergoes a phase change of roughly 0.8 rad when considering the first and second halves of the MOST data set, which are separated in median time by 3.38 days. In contrast, the Doppler signal is stable in the combined High-Accuracy Radial velocity Planet Searcher and High Resolution Echelle Spectrometer radial velocities for over 4700 days and does not appear to vary in time in amplitude, phase, period, or as a function of extracted wavelength. We consider a variety of starspot scenarios and find it challenging to simultaneously explain the rapidly varying photometric signal and the stable radial velocity signal as being caused by starspots corotating on the stellar surface. This suggests that the origin of the Doppler periodicity might be the gravitational tug of a planet orbiting the star in spin-orbit resonance. For such a scenario and no spin-orbit misalignment, the measured vsini indicates an inclination angle of 15.5+/-2.5{deg} and a planetary companion mass of 0.237+/-0.047 M_Jup_.
- ID:
- ivo://CDS.VizieR/J/AJ/155/126
- Title:
- Radial velocities & photometry of the K dwarf HD26965
- Short Name:
- J/AJ/155/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a radial velocity signal that can be interpreted as a planetary-mass candidate orbiting the K dwarf HD 26965, with an orbital period of 42.364+/-0.015 days, or alternatively, as the presence of residual, uncorrected rotational activity in the data. Observations include data from HIRES, PFS, CHIRON, and HARPS, where 1111 measurements were made over 16 years. Our best solution for HD 26965 b is consistent with a super-Earth that has a minimum mass of 6.92+/-0.79 M_{Earth}_ orbiting at a distance of 0.215+/-0.008 au from its host star. We have analyzed the correlation between spectral activity indicators and the radial velocities from each instrument, showing moderate correlations that we include in our model. From this analysis, we recover a ~38-day signal, which matches some literature values of the stellar rotation period. However, from independent Mt. Wilson HK data for this star, we find evidence for a significant 42-day signal after subtraction of longer period magnetic cycles, casting doubt on the planetary hypothesis for this period. Although our statistical model strongly suggests that the 42-day signal is Doppler in origin, we conclude that the residual effects of stellar rotation are difficult to fully model and remove from this data set, highlighting the difficulties to disentangle small planetary signals and photospheric noise, particularly when the orbital periods are close to the rotation period of the star. This study serves as an excellent test case for future works that aim to detect small planets orbiting "Sun-like" stars using radial velocity measurements.
- ID:
- ivo://CDS.VizieR/J/AJ/155/255
- Title:
- Radial velocity and activity measurements of HAT-P-11
- Short Name:
- J/AJ/155/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HAT-P-11 is a mid-K dwarf that hosts one of the first Neptune-sized planets found outside the solar system. The orbit of HAT-P-11b is misaligned with the star's spin-one of the few known cases of a misaligned planet orbiting a star less massive than the Sun. We find an additional planet in the system based on a decade of precision radial velocity (RV) measurements from Keck/High Resolution Echelle Spectrometer. HAT-P-11c is similar to Jupiter in its mass (M_P_sin i=1.6+/-0.1 M_J_) and orbital period (P=9.3_-0.5_^+1.0^ year), but has a much more eccentric orbit (e=0.60+/-0.03). In our joint modeling of RV and stellar activity, we found an activity-induced RV signal of ~7 m/s, consistent with other active K dwarfs, but significantly smaller than the 31 m/s reflex motion due to HAT-P-11c. We investigated the dynamical coupling between HAT-P-11b and c as a possible explanation for HAT-P-11b's misaligned orbit, finding that planet-planet Kozai interactions cannot tilt planet b's orbit due to general relativistic precession; however, nodal precession operating on million year timescales is a viable mechanism to explain HAT-P-11b's high obliquity. This leaves open the question of why HAT-P-11c may have such a tilted orbit. At a distance of 38 pc, the HAT-P-11 system offers rich opportunities for further exoplanet characterization through astrometry and direct imaging.
- ID:
- ivo://CDS.VizieR/J/AJ/157/33
- Title:
- Radial velocity exploration of {epsilon} Eridani
- Short Name:
- J/AJ/157/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most sensitive direct imaging and radial velocity (RV) exploration of {epsilon} Eridani to date. {epsilon} Eridani is an adolescent planetary system, reminiscent of the early solar system. It is surrounded by a prominent and complex debris disk that is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 yr ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 yr, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7 {mu}m) with the vortex coronagraph recently installed in W.M. Keck Observatory's infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. {epsilon} Eridani b has a mass of 0.78_-0.12_^+0.38^ M_Jup_ and is orbiting {epsilon} Eridani at about 3.48+/-0.02 au with a period of 7.37+/-0.07 yr. The eccentricity of {epsilon} Eridani b's orbit is 0.07_-0.05_^+0.06^, an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet-disk interactions and prospects for future detection and characterization with the James Webb Space Telescope.
