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Hartman, J. D., Jordan, A., Bayliss, D., Bakos, G. A., Bento, J., Bhatti, W., et al. (2020). HATS-47b, HATS-48Ab, HATS-49b, and HATS-72b: Four Warm Giant Planets Transiting K Dwarfs. Astron. J., 159(4), 23 pp.
Abstract: We report the discovery of four transiting giant planets around K dwarfs. The planets HATS-47b, HATS-48Ab, HATS49b, and HATS-72b have masses of 0.369+ 0.0210.031MJ, 0.243+ 0.0300.022 MJ, 0.353+ 0.0270.038 MJ, and 0.1254. 0.0039 MJ, respectively, and radii of 1.117. 0.014 RJ, 0.800. 0.015 RJ, 0.765. 0.013 RJ, and 0.7224. 0.0032 RJ, respectively. The planets orbit close to their host stars with orbital periods of 3.9228 days, 3.1317 days, 4.1480 days, and 7.3279 days, respectively. The hosts are main-sequence K dwarfs with masses of 0.674+ 0.0120.016.M, 0.7279. 0.0066.M, 0.7133. 0.0075.M, and 0.7311. 0.0028, and with V-band magnitudes of V = 14.829. 0.010, 14.35. 0.11, 14.998. 0.040 and 12.469. 0.010. The super-Neptune HATS-72b (a.k.a. WASP-191b and TOI 294.01) was independently identified as a transiting planet candidate by the HATSouth, WASP, and TESS surveys, and we present a combined analysis of all of the data gathered by each of these projects (and their follow-up programs). An exceptionally precise mass is measured for HATS-72b thanks to high-precision radial velocity (RV) measurements obtained with VLT/ESPRESSO, FEROS, HARPS, and Magellan/PFS. We also incorporate TESS observations of the warm Saturn-hosting systems HATS-47 (a.k.a. TOI.1073.01), HATS-48A, and HATS-49. HATS-47 was independently identified as a candidate by the TESS team, while the other two systems were not previously identified from the TESS data. The RV orbital variations are measured for these systems using Magellan/PFS. HATS-48A has a resolved 5.. 4 neighbor in Gaia.DR2, which is a common-proper-motion binary star companion to HATS-48A with a mass of 0.22.M and a current projected physical separation of similar to 1400 au.
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Jordan, A., Brahm, R., Espinoza, N., Henning, T., Jones, M. I., Kossakowski, D., et al. (2020). TOI-677b: A Warm Jupiter (P=11.2 days) on an Eccentric Orbit Transiting a Late F-type Star. Astron. J., 159(4), 10 pp.
Abstract: We report the discovery of TOI-677.b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI-677.b has a mass of M-p = 1.236(-0.067)(+0.069) M-J, a radius of R-P = 1.170 +/- 0.03 R-J, and orbits its bright host star (V=.9.8 mag) with an orbital period of 11.23660 +/- 0.00011 d, on an eccentric orbit with e = 0.435 +/- 0.024. The host star has a mass of M-star = 1.181 +/- 0.058 M-circle dot, a radius of R. = 1.28(-0.03)(+0.03) R-circle dot, an age of 2.92(-0.73)(+0.80) Gyr and solar metallicity, properties consistent with a main-sequence late-F star with T-eff = 6295 +/- 77 K. We find evidence in the radial velocity measurements of a secondary long-term signal, which could be due to an outer companion. The TOI-677.b system is a well-suited target for Rossiter-Mclaughlin observations that can constrain migration mechanisms of close-in giant planets.
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Schlecker, M., Kossakowski, D., Brahm, R., Espinoza, N., Henning, T., Carone, L., et al. (2020). A highly eccentric warm jupiter orbiting TIC 237913194. Astron. J., 160(6), 275.
Abstract: The orbital parameters of warm Jupiters serve as a record of their formation history, providing constraints on formation scenarios for giant planets on close and intermediate orbits. Here, we report the discovery of TIC.237913194b, detected in full-frame images from Sectors 1 and 2 of the Transiting Exoplanet Survey Satellite (TESS), ground-based photometry (Chilean-Hungarian Automated Telescope, Las Cumbres Observatory Global Telescope), and Fiber-fed Extended Range Optical Spectrograph radial velocity time series. We constrain its mass to M-P = 1.942(-0.091)(+0.091) M-J and its radius to R-P = 1.117(-0.047)(+0.054) R-J, implying a bulk density similar to Neptune's. It orbits a G-type star (M-* = 1.026(-0.055)(+0.057) M-circle dot, V = 12.1 mag) with a period of 15.17 days on one of the most eccentric orbits of all known warm giants (e approximate to 0.58). This extreme dynamical state points to a past interaction with an additional, undetected massive companion. A tidal evolution analysis showed a large tidal dissipation timescale, suggesting that the planet is not a progenitor for a hot Jupiter caught during its high-eccentricity migration. TIC.237913194b further represents an attractive opportunity to study the energy deposition and redistribution in the atmosphere of a warm Jupiter with high eccentricity.
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Trifonov, T., Wollbold, A., Kurster, M., Eberhardt, J., Stock, S., Henning, T., et al. (2022). A New Third Planet and the Dynamical Architecture of the HD33142 HD 33142 Planetary System. Astron. J., 164(4), 156.
Abstract: Based on recently-taken and archival HARPS, FEROS, and HIRES radial velocities (RVs), we present evidence for a new planet orbiting the first ascent red giant star HD 33142 (with an improved mass estimate of M1.52 +/- 0.03 M-circle dot), already known to host two planets. We confirm the Jovian-mass planets HD 33142b and c, with periods of P-b = 330.0(-0.4)(+0.4) days and P-c = 810. 2(-4.2)(+3.8) days and minimum dynamical masses of m(b) sin i =1.26(-0.05)(+0.05) M-Jup and m(c) sin i = 0.89(-0.05)(+0.06) M-Jup, respectively. Furthermore, our periodogram analysis of the precise RVs shows strong evidence for a short-period Doppler signal in the residuals of a two-planet Keplerian fit, which we interpret as a third, Saturn-mass planet with m(d) sin i = 0.20(-)(0.03)(+0.02) M-Jup in a close-in orbit with an orbital period of P-d = 89.9(-0.1)(+0.1) days. We study the dynamical behavior of the three-planet system configuration with an N-body integration scheme, finding it to be long-term stable with the planets alternating between low and moderate eccentricity episodes. We also perform N-body simulations, including stellar evolution and second-order dynamical effects such as planet-stellar tides and stellar mass loss on the way to the white dwarf phase. We find that planets HD 33142b, c, and d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration. These results make the HD 33142 system an essential benchmark for planet population statistics of the multiple-planet systems found around evolved stars.
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Weaver, I. C., Lopez-Morales, M., Alam, M. K., Espinoza, N., Rackham, B. V., Goyal, J. M., et al. (2021). ACCESS: An Optical Transmission Spectrum of the High-gravity Hot Jupiter HAT-P-23b. Astron. J., 161(6), 278.
Abstract: We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 angstrom and 9269 angstrom in 200 angstrom bins, and with a median precision of 247 ppm per bin. HAT-P-23b's relatively high surface gravity (g approximate to 30 m s(-2)), combined with updated stellar and planetary parameters from Gaia DR2, gives a five-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/near-IR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.
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