Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: We report the discovery of a 1.32$^{+0.10}_{-0.10}$ $\mathrm{M_{\rm Jup}}$
planet orbiting on a 75.12 day period around the G3V $10.8^{+2.1}_{-3.6}$ Gyr
old star TOI-5542 (TIC 466206508; TYC 9086-1210-1). The planet was first
detected by the Transiting Exoplanet Survey Satellite (TESS) as a single
transit event in TESS Sector 13. A second transit was observed 376 days later
in TESS Sector 27. The planetary nature of the object has been confirmed by
ground-based spectroscopic and radial velocity observations from the CORALIE
and HARPS spectrographs. A third transit event was detected by the ground-based
facilities NGTS, EulerCam, and SAAO. We find the planet has a radius of
1.009$^{+0.036}_{-0.035}$ $\mathrm{R_{\rm Jup}}$ and an insolation of
9.6$^{+0.9}_{-0.8}$ $S_{\oplus}$, along with a circular orbit that most likely
formed via disk migration or in situ formation, rather than high-eccentricity
migration mechanisms. Our analysis of the HARPS spectra yields a host star
metallicity of [Fe/H] = $-$0.21$\pm$0.08, which does not follow the traditional
trend of high host star metallicity for giant planets and does not bolster
studies suggesting a difference among low- and high-mass giant planet host star
metallicities. Additionally, when analyzing a sample of 216 well-characterized
giant planets, we find that both high masses (4 $\mathrm{M_{\rm Jup}}$
$
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: We present the discovery of TOI-2136b, a sub-Neptune planet transiting every 7.85 days a nearby M4.5V-type star, identified through photometric measurements from the TESS mission. The host star is located $33$ pc away with a radius of $R_{\ast} = 0.34\pm0.02\ R_{\odot}$, a mass of $0.34\pm0.02\ M_{\odot}$ and an effective temperature of $\rm 3342\pm100\ K$. We estimate its stellar rotation period to be $75\pm5$ days based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multi-wavelength photometry, high-angular-resolution imaging observations, and precise radial velocities from CFHT/SPIRou. Our joint analysis reveals that the planet has a radius of $2.19\pm0.17\ R_{\oplus}$, and a mass measurement of $6.4\pm2.4M_{\oplus}$. The mass and radius of TOI2136b is consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136b falls close to the radius valley for low-mass stars predicted by the thermally driven atmospheric mass loss models, making it an interesting target for future studies of its interior structure and atmospheric properties.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract: We present the Distant Giants Survey, a three-year radial velocity (RV) campaign to measure P(DG|CS), the conditional occurrence of distant giant planets (DG; M_p ~ 0.3 - 13 M_J, P > 1 year) in systems hosting a close-in small planet (CS; R_p < 10 R_E). For the past two years, we have monitored 47 Sun-like stars hosting small transiting planets detected by TESS. We present the selection criteria used to assemble our sample and report the discovery of two distant giant planets, TOI-1669 b and TOI-1694 c. For TOI-1669 b we find that Msin i = 0.573 +/- 0.074 M_J, P = 502 +/- 16 days, and e < 0.27, while for TOI-1694 c, Msin i = 1.05 +/- 0.05 M_J, P = 389.2 +/- 3.9 days, and e = 0.18 +/- 0.05. We also confirmed the 3.8-day transiting planet TOI-1694 b by measuring a true mass of M = 26.1 +/- 2.2 M_E. We also confirmed the 3.8-day transiting planet TOI-1694 b by measuring a true mass of M = 26.1 +/- 2.2 M_E. At the end of the Distant Giants Survey, we will incorporate TOI-1669 b and TOI-1694 c into our calculation of P(DG|CS), a crucial statistic for understanding the relationship between outer giants and small inner companions.
Peer Review Status:Awaiting Review