Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Zhoujian Zhang
Brendan P. Bowler
Trent J. Dupuy
Timothy D. Brandt
G. Mirek Brandt
William D. Cochran
Michael Endl
Phillip J. MacQueen
Kaitlin M. Kratter
Howard T. Isaacson
Kyle Franson
Adam L. Kraus
Caroline V. Morley
Yifan Zhou
Abstract： We present the latest and most precise characterization of the architecture for the ancient ($\approx 11$ Gyr) Kepler-444 system, which is composed of a K0 primary star (Kepler-444 A) hosting five transiting planets, and a tight M-type spectroscopic binary (Kepler-444 BC) with an A-BC projected separation of 66 au. We have measured the system's relative astrometry using the adaptive optics imaging from Keck/NIRC2 and Kepler-444 A's radial velocities from the Hobby Eberly Telescope, and re-analyzed relative radial velocities between BC and A from Keck/HIRES. We also include the Hipparcos-Gaia astrometric acceleration and all published astrometry and radial velocities into an updated orbit analysis of BC's barycenter. These data greatly extend the time baseline of the monitoring and lead to significant updates to BC's barycentric orbit compared to previous work, including a larger semi-major axis ($a = 52.2^{+3.3}_{-2.7}$ au), a smaller eccentricity ($e = 0.55 \pm 0.05$), and a more precise inclination ($i =85.4^{+0.3}_{-0.4}$ degrees). We have also derived the first dynamical masses of B and C components. Our results suggest Kepler-444~A's protoplanetary disk was likely truncated by BC to a radius of $\approx 8$ au, which resolves the previously noticed tension between Kepler-444 A's disk mass and planet masses. Kepler-444 BC's barycentric orbit is likely aligned with those of A's five planets, which might be primordial or a consequence of dynamical evolution. The Kepler-444 system demonstrates that compact multi-planet systems residing in hierarchical stellar triples can form at early epochs of the Universe and survive their secular evolution throughout cosmic time.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Caleb I. Cañas
Shubham Kanodia
Jessica Libby-Roberts
Andrea S. J. Lin
Maria Schutte
Luke Powers
Sinclaire Jones
Andrew Monson
Songhu Wang
Guðmundur Stefánsson
William D. Cochran
Paul Robertson
Suvrath Mahadevan
Adam F. Kowalski
John Wisniewski
Brock A. Parker
Alexander Larsen
Franklin A. L. Chapman
Henry A. Kobulnicky
Arvind F. Gupta
Abstract： We confirm the planetary nature of two gas giants discovered by TESS to transit M dwarfs with stellar companions at wide separations. TOI-3984 A ($J=11.93$) is an M4 dwarf hosting a short-period ($4.353326 \pm 0.000005$ days) gas giant ($M_p=0.14\pm0.03~\mathrm{M_{J}}$ and $R_p=0.71\pm0.02~\mathrm{R_{J}}$) with a wide separation white dwarf companion. TOI-5293 A ($J=12.47$) is an M3 dwarf hosting a short-period ($2.930289 \pm 0.000004$ days) gas giant ($M_p=0.54\pm0.07~\mathrm{M_{J}}$ and $R_p=1.06\pm0.04~\mathrm{R_{J}}$) with a wide separation M dwarf companion. We characterize both systems using a combination of ground-based and space-based photometry, speckle imaging, and high-precision radial velocities from the Habitable-zone Planet Finder and NEID spectrographs. TOI-3984 A b ($T_{eq}=563\pm15$ K and $\mathrm{TSM}=138_{-27}^{+29}$) and TOI-5293 A b ($T_{eq}=675_{-30}^{+42}$ K and $\mathrm{TSM}=92\pm14$) are two of the coolest gas giants among the population of hot Jupiter-sized gas planets orbiting M dwarfs and are favorable targets for atmospheric characterization of temperate gas giants and three-dimensional obliquity measurements to probe system architecture and migration scenarios.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Zhoujian Zhang
Brendan P. Bowler
Trent J. Dupuy
Timothy D. Brandt
G. Mirek Brandt
William D. Cochran
Michael Endl
Phillip J. MacQueen
Kaitlin M. Kratter
Howard T. Isaacson
Kyle Franson
Adam L. Kraus
Caroline V. Morley
Yifan Zhou
Abstract： We present the latest and most precise characterization of the architecture for the ancient ($\approx 11$ Gyr) Kepler-444 system, which is composed of a K0 primary star (Kepler-444 A) hosting five transiting planets, and a tight M-type spectroscopic binary (Kepler-444 BC) with an A-BC projected separation of 66 au. We have measured the system's relative astrometry using the adaptive optics imaging from Keck/NIRC2 and Kepler-444 A's radial velocities from the Hobby Eberly Telescope, and re-analyzed relative radial velocities between BC and A from Keck/HIRES. We also include the Hipparcos-Gaia astrometric acceleration and all published astrometry and radial velocities into an updated orbit analysis of BC's barycenter. These data greatly extend the time baseline of the monitoring and lead to significant updates to BC's barycentric orbit compared to previous work, including a larger semi-major axis ($a = 52.2^{+3.3}_{-2.7}$ au), a smaller eccentricity ($e = 0.55 \pm 0.05$), and a more precise inclination ($i =85.4^{+0.3}_{-0.4}$ degrees). We have also derived the first dynamical masses of B and C components. Our results suggest Kepler-444~A's protoplanetary disk was likely truncated by BC to a radius of $\approx 8$ au, which resolves the previously noticed tension between Kepler-444 A's disk mass and planet masses. Kepler-444 BC's barycentric orbit is likely aligned with those of A's five planets, which might be primordial or a consequence of dynamical evolution. The Kepler-444 system demonstrates that compact multi-planet systems residing in hierarchical stellar triples can form at early epochs of the Universe and survive their secular evolution throughout cosmic time.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Andrea S. J. Lin
Jessica E. Libby-Roberts
Jaime A. Alvarado-Montes
Caleb I. Cañas
Shubham Kanodia
Leslie Hebb
Eric L. N. Jensen
Suvrath Mahadevan
Luke C. Powers
Tera N. Swaby
John Wisniewski
Corey Beard
Chad F. Bender
Cullen H. Blake
William D. Cochran
Scott A. Diddams
Robert C. Frazier
Connor Fredrick
Michael Gully-Santiago
Samuel Halverson
Abstract： TOI-1899~b is a rare exoplanet, a temperate Warm Jupiter orbiting an M-dwarf, first discovered by \citet{Canas2020_toi1899} from a TESS single-transit event. Using new radial velocities (RVs) from the precision RV spectrographs HPF and NEID, along with additional TESS photometry and ground-based transit follow-up, we are able to derive a much more precise orbital period of $P = 29.090312_{-0.000035}^{+0.000036}$~d, along with a radius of $R_p = 0.99\pm0.03$~\unit{R_{J}}. We have also improved the constraints on planet mass, $M_p = 0.67\pm{0.04}$~\unit{M_{J}}, and eccentricity, which is consistent with a circular orbit at 2$\sigma$ ($e = 0.044_{-0.027}^{+0.029}$). TOI-1899~b occupies a unique region of parameter space as the coolest known ($T_{eq} \approx$ 380~K) Jovian-sized transiting planet around an M-dwarf; we show that it has great potential to provide clues regarding the formation and migration mechanisms of these rare gas giants through transmission spectroscopy with JWST as well as studies of tidal evolution.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Jessica E. Libby-Roberts
Maria Schutte
Leslie Hebb
Shubham Kanodia
Caleb Canas
Gudmundur Stefansson
Andrea S. J. Lin
Suvrath Mahadevan
Winter Parts
Luke Powers
John Wisniewski
Chad F. Bender
William D. Cochran
Scott A. Diddams
Mark E. Everett
Arvind F. Gupta
Samuel Halverson
Henry A. Kobulnicky
Adam F. Kowalski
Alexander Larsen
Abstract： We perform an in-depth analysis of the recently validated TOI-3884 system, an M4 dwarf star with a transiting super-Neptune. Using high precision light curves obtained with the 3.5 m Apache Point Observatory and radial velocity observations with the Habitable-zone Planet Finder (HPF), we derive a planetary mass of 32.6$^{+7.3}_{-7.4}$ M$_{\oplus}$ and radius of 6.4 $\pm$ 0.2 R$_{\oplus}$. We detect a distinct star spot crossing event occurring just after ingress and spanning half the transit for every transit. We determine this spot feature to be wavelength-dependent with the amplitude and duration evolving slightly over time. Best-fit star spot models show that TOI-3884b possesses a misaligned ($\lambda$ = 75 $\pm$ 10$^\circ$) orbit which crosses a giant pole-spot. This system presents a rare opportunity for studies into the nature of both a misaligned super-Neptune and spot evolution on an active mid-M dwarf.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shubham Kanodia
Suvrath Mahadevan
Jessica Libby-Roberts
Gudmundur Stefansson
Caleb I. Canas
Anjali A. A. Piette
Alan Boss
Johanna Teske
John Chambers
Greg Zeimann
Andrew Monson
Paul Robertson
Joe P. Ninan
Andrea S. J. Lin
Chad F. Bender
William D. Cochran
Scott A. Diddams
Arvind F. Gupta
Samuel Halverson
Suzanne Hawley
Abstract： We present the discovery of TOI-5205~b, a transiting Jovian planet orbiting a solar metallicity M4V star, which was discovered using Transiting Exoplanet Survey Satellite photometry and then confirmed using a combination of precise radial velocities, ground-based photometry, spectra, and speckle imaging. TOI-5205~b has one of the highest mass ratios for M dwarf planets with a mass ratio of almost 0.3$\%$, as it orbits a host star that is just $0.392 \pm 0.015$ \solmass{}. Its planetary radius is $1.03 \pm 0.03~R_J$, while the mass is $1.08 \pm 0.06~M_J$. Additionally, the large size of the planet orbiting a small star results in a transit depth of $\sim 7\%$, making it one of the deepest transits of a confirmed exoplanet orbiting a main-sequence star. The large transit depth makes TOI-5205~b a compelling target to probe its atmospheric properties, as a means of tracing the potential formation pathways. While there have been radial-velocity-only discoveries of giant planets around mid-M dwarfs, this is the first transiting Jupiter with a mass measurement discovered around such a low-mass host star. The high mass of TOI-5205~b stretches conventional theories of planet formation and disk scaling relations that cannot easily recreate the conditions required to form such planets.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Emil Knudstrup
Simon H. Albrecht
Davide Gandolfi
Marcus L. Marcussen
Elisa Goffo
Luisa M. Serrano
Fei Dai
Seth Redfield
Teruyuki Hirano
Szilárd Csizmadia
William D. Cochran
Hans J. Deeg
Malcolm Fridlund
Kristine W. F. Lam
John H. Livingston
Rafael Luque
Norio Narita
Enric Palle
Carina M. Persson
Vincent Van Eylen
Abstract： TOI-640 b is a hot, puffy Jupiter with a mass of $0.57 \pm 0.02$ M$_{\rm J}$ and radius of $1.72 \pm 0.05$ R$_{\rm J}$, orbiting a slightly evolved F-type star with a separation of $6.33^{+0.07}_{-0.06}$ R$_\star$. Through spectroscopic in-transit observations made with the HARPS spectrograph, we measured the Rossiter-McLaughlin effect, analysing both in-transit radial velocities and the distortion of the stellar spectral lines. From these observations, we find the host star to have a projected obliquity of $\lambda=184\pm3^\circ$. From the TESS light curve, we measured the stellar rotation period, allowing us to determine the stellar inclination, $i_\star=23^{+3\circ}_{-2}$, meaning we are viewing the star pole-on. Combining this with the orbital inclination allowed us to calculate the host star obliquity, $\psi=104\pm2^\circ$. TOI-640 b joins a group of planets orbiting over stellar poles within the range $80^\circ-125^\circ$. The origin of this orbital configuration is not well understood.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
F. Murgas
G. Nowak
T. Masseron
H. Parviainen
R. Luque
E. Pallé
Judith Korth
I. Carleo
Sz. Csizmadia
E. Esparza-Borges
Ahlam Alqasim
William D. Cochran
Fei Dai
Hans J. Deeg
D. Gandolfi
Elisa Goffo
Petr Kabáth
K. W. F. Lam
John Livingston
Alexandra Muresan
Abstract： We used TESS light curves and HARPS-N spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate found around the star HD 20329 (TOI-4524). We performed a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. We confirm and characterize HD 20329b, an ultra-short-period (USP) planet transiting a solar-type star. The host star (HD 20329, $V = 8.74$ mag, $J = 7.5$ mag) is characterized by its G5 spectral type with $\mathrm{M}_\star= 0.90 \pm 0.05$ M$_\odot$, $\mathrm{R}_\star = 1.13 \pm 0.02$ R$_\odot$, and $\mathrm{T}_{\mathrm{eff}} = 5596 \pm 50$ K; it is located at a distance $d= 63.68 \pm 0.29$ pc. By jointly fitting the available TESS transit light curves and follow-up radial velocity measurements, we find an orbital period of $0.9261 \pm (0.5\times 10^{-4})$ days, a planetary radius of $1.72 \pm 0.07$ $\mathrm{R}_\oplus$, and a mass of $7.42 \pm 1.09$ $\mathrm{M}_\oplus$, implying a mean density of $\rho_\mathrm{p} = 8.06 \pm 1.53$ g cm$^{-3}$. HD 20329b joins the $\sim$30 currently known USP planets with radius and Doppler mass measurements.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Teruyuki Hirano
Fei Dai
John H. Livingston
Yui Kasagi
Norio Narita
Hiroyuki Tako Ishikawa
Sascha Grziwa
Kristine W. F. Lam
Kohei Miyakawa
Luisa M. Serrano
Yuji Matsumoto
Eiichiro Kokubo
Tadahiro Kimura
Masahiro Ikoma
Joshua N. Winn
John P. Wisniewski
Hiroki Harakawa
Huan-Yu Teng
William D. Cochran
Akihiko Fukui
Abstract： We report on the discovery of an Earth-sized transiting planet ($R_p=1.015\pm0.051\,R_\oplus$) in a $P=4.02$ day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc. The planet candidate was first identified by analyzing the light curve data by the K2 mission, and is here shown to exist in the most recent data from TESS. Combining the light curves with the data secured by our follow-up observations including high-resolution imaging and near infrared spectroscopy with IRD, we rule out false positive scenarios, finding a low false positive probability of $2\times 10^{-4}$. Based on IRD's radial velocities of K2-415, which were sparsely taken over three years, we obtain the planet mass of $3.0\pm 2.7\,M_\oplus$ ($M_p<7.5\,M_\oplus$ at $95\,\%$ confidence) for K2-415b. Being one of the lowest mass stars ($\approx 0.16\,M_\odot$) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.
Peer Review Status:Awaiting Review
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