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Bozhilov, V., Antonova, D., Hobson, M. J., Brahm, R., Jordan, A., Henning, T., et al. (2023). A 2:1 Mean-motion Resonance Super-Jovian Pair Revealed by TESS, FEROS, and HARPS. Astrophys. J. Lett., 946(2), L36.
Abstract: We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss survey to constrain the transiting body's period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of 76.80(-0.06)(+0.06) and 155.3(-0.7)(+0.7) days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of 6.14(-0.42)(+0.39) M-Jup and a radius of 1.00(-0.04)(+0.04) R-Jup, and an outer planet with a minimum mass of 8.02(-0.18)(+0.18) M-Jup, indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong firstorder, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, V approximate to 11.9 mag, the relatively short orbital period (P-b = 76.80(-0.06)(+0.06) days), and pronounced eccentricity (e = 0.448(-0.029)(+0.029)) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope and ground-based extremely large telescopes.
Keywords: GIANT PLANETS; ECCENTRICITY; EVOLUTION; EXOPLANET; ORIGIN; MASS
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Brahm, R., Ulmer-Moll, S., Hobson, M. J., Jordan, A., Henning, T., Trifonov, T., et al. (2023). Three Long-period Transiting Giant Planets from TESS. Astron. J., 165(6), 227.
Abstract: We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single-transit events in the light curves generated from the full-frame images of the Transiting Exoplanet Survey Satellite. Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of M ( P ) = 0.30 +/- 0.04 M (J), a radius of R ( P ) = 1.00 +/- 0.02 R (J), and a low-eccentricity orbit (e = 0.15 +/- 0.05) with a period of P = 30.08364 +/- 0.00005 days. TOI 2338b has a mass of M ( P ) = 5.98 +/- 0.20 M (J), a radius of R ( P ) = 1.00 +/- 0.01 R (J), and a highly eccentric orbit (e = 0.676 +/- 0.002) with a period of P = 22.65398 +/- 0.00002 days. Finally, TOI 2589b has a mass of M ( P ) = 3.50 +/- 0.10 M (J), a radius of R ( P ) = 1.08 +/- 0.03 R (J), and an eccentric orbit (e = 0.522 +/- 0.006) with a period of P = 61.6277 +/- 0.0002 days. TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.
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Eberhardt, J., Hobson, M. J., Henning, T., Trifonov, T., Brahm, R., Espinoza, N., et al. (2023). Three Warm Jupiters around Solar-analog Stars Detected with TESS. Astron. J., 166(6), 271.
Abstract: We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every similar to 13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m(p) = 9.3(-0.2)(+0.2)Mjup and a radius of r(p) = 0.93(-0.2)(+0.2) jup. With a mean density of r = 14.4 1.0 g cm + 0.9 -3, TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of similar to 8.3 days and an eccentricity of e = 0.32 0.02 + 0.02. TOI-2416 b is more massive than Jupiter with m(p) = 3.0 +0.09 M 0.10 jup, however is significantly smaller with a radius of r(p) = 0.88 + 0.02 ,R 0.02 jup, leading to a high mean density of r = 5.4 0.3 g cm + 0.3 -3. TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every similar to 7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m(p)=0.64- + 0.04 M 0.04 jup, and is consistent with an inflated radius of r(p)= 1.00- + 0.03 R 0.02 jup, leading to a low mean density of r = 0.79 0.08 g cm + 0.08 -3. The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of 860 10 +10 K, 1080 10 +10 K, and 1100-20 +20 K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters.
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Eberhardt, J., Trifonov, T., Kurster, M., Stock, S., Henning, T., Wollbold, A., et al. (2022). Dynamical Architecture of the HD 107148 Planetary System. Astron. J., 163(5), 198.
Abstract: We present an independent Doppler validation and dynamical orbital analysis of the two-planet system HD 107148, which was recently announced in Rosenthal et al. Our detailed analyses are based on literature HIRES data and newly obtained HARPS and CARMENES radial-velocity (RV) measurements as part of our survey in search for additional planets around single-planet systems. We perform a periodogram analysis of the available HIRES and HARPS precise RVs and stellar activity indicators. We do not find any apparent correlation between the RV measurements and the stellar activity indicators, thus linking the two strong periodicities to a moderately compact multiplanet system. We carry out orbital fitting analysis by testing various one- and two-planet orbital configurations and studying the posterior probability distribution of the fitted parameters. Our results solidify the existence of a Saturn-mass planet (HD 107148b, discovered first) with a period of P (b) similar to 77.2 days and a second, eccentric (e (c) similar to 0.4), Neptune-mass exoplanet (HD 107148c) with an orbital period of P (c) similar to 18.3 days. Finally, we investigate the two-planet system's long-term stability and overall orbital dynamics with the posterior distribution of our preferred orbital configuration. Our N-body stability simulations show that the system is long-term stable and exhibits large secular osculations in eccentricity but in no particular mean motion resonance configuration. The HD 107148 system, consisting of a solar-type main-sequence star with two giant planets in a rare configuration, features a common proper-motion white dwarf companion and is therefore a valuable target for understanding the formation and evolution of planetary systems.
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Hobson, M. J., Trifonov, T., Henning, T., Jordan, A., Rojas, F., Espinoza, N., et al. (2023). Alert Results TOI-199 b: A Well-characterized 100 day Transiting Warm Giant Planet with TTVs Seen from Antarctica 41 of 41 TOI-199 b: A Well-characterized 100 day Transiting Warm Giant Planet with TTVs Seen from Antarctica. Astron. J., 166(5), 201.
Abstract: We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 hr long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199 b has a 104.854-0.002+0.001day period, a mass of 0.17 +/- 0.02 M J, and a radius of 0.810 +/- 0.005 R J. It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations (TTVs), pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the nontransiting companion TOI-199 c, which has a period of 273.69-0.22+0.26days and an estimated mass of 0.28-0.01+0.02MJ . This period places it within the conservative habitable zone.
Keywords: MAGNETIC ACTIVITY; ERROR-CORRECTION; EXOPLANET YIELD; I-ARCHITECTURE; ASTEP 400; MODEL; TELESCOPE; SYSTEMS; JUPITER; CODE
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Jones, M. I., Reinarz, Y., Brahm, R.., Tala Pinto, M., Eberhardt, J., Rojas, F., et al. (2024). A long-period transiting substellar companion in the super-Jupiters to brown dwarfs mass regime and a prototypical warm-Jupiter detected by TESS. Astron. Astrophys., 683, A192.
Abstract: We report on the confirmation and follow-up characterization of two long-period transiting substellar companions on low-eccentricity orbits around TIC 4672985 and TOI-2529, whose transit events were detected by the TESS space mission. Ground-based photometric and spectroscopic follow-up from different facilities, confirmed the substellar nature of TIC 4672985 b, a massive gas giant in the transition between the super-Jupiters and brown dwarfs mass regime. From the joint analysis we derived the following orbital parameters: P = 69.0480(-0.0005)(+0.0004) d, M-p = 12.74(-1.01)(+1.01) M-J, R-p = 1.026(-0.067)(+0.065) R-J and e = 0.018(-0.004)(+0.004). In addition, the RV time series revealed a significant trend at the similar to 350 m s(-1) yr(-1) level, which is indicative of the presence of a massive outer companion in the system. TIC 4672985 b is a unique example of a transiting substellar companion with a mass above the deuterium-burning limit, located beyond 0.1 AU and in a nearly circular orbit. These planetary properties are difficult to reproduce from canonical planet formation and evolution models. For TOI-2529 b, we obtained the following orbital parameters: P = 64.5949(-0.0003)(+0.0003) d, M-p = 2.340(-0.195)(+0.197) M-J, R-p = 1.030(-0.050)(+0.050) R-J and e = 0.021(-0.015)(+0.024), making this object a new example of a growing population of transiting warm giant planets.
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Sha, L. Z., Vanderburg, A. M., Huang, C. X., Armstrong, D. J., Brahm, R., Giacalone, S., et al. (2023). TESS spots a mini-neptune interior to a hot saturn in the TOI-2000 system. Mon. Not. Roy. Astron. Soc., 524(1), 1113–1138.
Abstract: Hot jupiters (P < 10 d, M > 60 M.) are almost always found alone around their stars, but four out of hundreds known have inner companion planets. These rare companions allow us to constrain the hot jupiter's formation history by ruling out high-eccentricity tidal migration. Less is known about inner companions to hot Saturn-mass planets. We report here the discovery of the TOI-2000 system, which features a hot Saturn-mass planet with a smaller inner companion. The mini-neptune TOI-2000 b (2.70 +/- 0.15 R-circle plus, 11.0 +/- 2.4 M.) is in a 3.10-d orbit, and the hot saturn TOI-2000 c (8.14(+0.31) (-0.30) R-circle plus, 81.7(-4.6)(+4.7) M.) is in a 9.13-d orbit. Both planets transit their host star TOI-2000 (TIC 371188886, V = 10.98, TESS magnitude = 10.36), a metal-rich ([Fe/H] = 0.439 (+0.041)(-0.043)) G dwarf 173 pc away. TESS observed the two planets in sectors 9-11 and 36-38, and we followed up with groundbased photometry, spectroscopy, and speckle imaging. Radial velocities from CHIRON, FEROS, and HARPS allowed us to confirm both planets by direct mass measurement. In addition, we demonstrate constraining planetary and stellar parameters with MIST stellar evolutionary tracks through Hamiltonian Monte Carlo under the PYMC framework, achieving higher sampling efficiency and shorter run time compared to traditional Markov chain Monte Carlo. Having the brightest host star in the V band among similar systems, TOI-2000 b and c are superb candidates for atmospheric characterization by the JWST, which can potentially distinguish whether they formed together or TOI-2000 c swept along material during migration to form TOI-2000 b.
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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.
Keywords: GAS GIANT PLANETS; STELLAR PARAMETERS; STARS; EVOLUTION; MASS; SEARCH; DWARF; II; MIGRATION; EXOPLANET
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