Stellar Obliquity of the Ultra-short-period Planet System HD 93963

We report an observation of the Rossiter–McLaughlin (RM) effect of the transiting planet HD 93963 Ac, a mini-Neptune planet orbiting a G0-type star with an orbital period of P _c  = 3.65 days, accompanied by an inner super-Earth planet with P _b  = 1.04 days. We observed a full transit of planet c o...

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Main Authors: Huan-Yu Teng, Fei Dai, Andrew W. Howard, Samuel Halverson, Howard Isaacson, Eiichiro Kokubo, Ryan A. Rubenzahl, Benjamin Fulton, Aaron Householder, Jack Lubin, Steven Giacalone, Luke Handley, Judah Van Zandt, Erik A. Petigura, J. M. Joel Ong, Pranav Premnath, Haochuan Yu, Steven R. Gibson, Kodi Rider, Arpita Roy, Ashley Baker, Jerry Edelstein, Chris Smith, Josh Walawender, Byeong-Cheol Lee, Yu-Juan Liu, Joshua N. Winn
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astronomical Journal
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Online Access:https://doi.org/10.3847/1538-3881/addab9
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author Huan-Yu Teng
Fei Dai
Andrew W. Howard
Samuel Halverson
Howard Isaacson
Eiichiro Kokubo
Ryan A. Rubenzahl
Benjamin Fulton
Aaron Householder
Jack Lubin
Steven Giacalone
Luke Handley
Judah Van Zandt
Erik A. Petigura
J. M. Joel Ong
Pranav Premnath
Haochuan Yu
Steven R. Gibson
Kodi Rider
Arpita Roy
Ashley Baker
Jerry Edelstein
Chris Smith
Josh Walawender
Byeong-Cheol Lee
Yu-Juan Liu
Joshua N. Winn
author_facet Huan-Yu Teng
Fei Dai
Andrew W. Howard
Samuel Halverson
Howard Isaacson
Eiichiro Kokubo
Ryan A. Rubenzahl
Benjamin Fulton
Aaron Householder
Jack Lubin
Steven Giacalone
Luke Handley
Judah Van Zandt
Erik A. Petigura
J. M. Joel Ong
Pranav Premnath
Haochuan Yu
Steven R. Gibson
Kodi Rider
Arpita Roy
Ashley Baker
Jerry Edelstein
Chris Smith
Josh Walawender
Byeong-Cheol Lee
Yu-Juan Liu
Joshua N. Winn
author_sort Huan-Yu Teng
collection DOAJ
description We report an observation of the Rossiter–McLaughlin (RM) effect of the transiting planet HD 93963 Ac, a mini-Neptune planet orbiting a G0-type star with an orbital period of P _c  = 3.65 days, accompanied by an inner super-Earth planet with P _b  = 1.04 days. We observed a full transit of planet c on 2024 May 3 UT with the Keck/Keck Planet Finder. The observed RM effect has an amplitude of ∼1 m s ^−1 and implies a sky-projected obliquity of $\lambda =1{4}_{-19}^{+17}$ degrees for HD 93963 Ac. Our dynamical analysis suggests that the two inner planets are likely well aligned with the stellar spin, to within a few degrees, thus allowing both to transit. Along with WASP-47, 55 Cnc, and HD 3167, HD 93963 is the fourth planetary system with an ultrashort-period planet and obliquity measurement(s) of any planet(s) in the system. HD 93963, WASP-47, and 55 Cnc favor largely coplanar orbital architectures, whereas HD 3167 has been reported to have a large mutual inclination (∼100°) between its transiting planets b and c. In this configuration, the probability that both planets transit is low. Moreover, one planet would quickly evolve to be nontransiting due to nodal precession. Future missions such as ESO/PLATO should detect the resulting transit duration variations. We encourage additional obliquity measurements of the HD 3167 system to better constrain its orbital architecture.
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spelling doaj-art-2b50a01dd95a488d960a18a72b716e612025-08-20T03:32:23ZengIOP PublishingThe Astronomical Journal1538-38812025-01-0117015110.3847/1538-3881/addab9Stellar Obliquity of the Ultra-short-period Planet System HD 93963Huan-Yu Teng0https://orcid.org/0000-0003-3860-6297Fei Dai1https://orcid.org/0000-0002-8958-0683Andrew W. Howard2https://orcid.org/0000-0001-8638-0320Samuel Halverson3https://orcid.org/0000-0003-1312-9391Howard Isaacson4https://orcid.org/0000-0002-0531-1073Eiichiro Kokubo5https://orcid.org/0000-0002-5486-7828Ryan A. Rubenzahl6https://orcid.org/0000-0003-3856-3143Benjamin Fulton7https://orcid.org/0000-0003-3504-5316Aaron Householder8https://orcid.org/0000-0002-5812-3236Jack Lubin9https://orcid.org/0000-0001-8342-7736Steven Giacalone10https://orcid.org/0000-0002-8965-3969Luke Handley11https://orcid.org/0000-0002-9305-5101Judah Van Zandt12https://orcid.org/0000-0002-4290-6826Erik A. Petigura13https://orcid.org/0000-0003-0967-2893J. M. Joel Ong14https://orcid.org/0000-0001-7664-648XPranav Premnath15https://orcid.org/0000-0001-5728-4735Haochuan Yu16https://orcid.org/0000-0002-0971-6078Steven R. Gibson17https://orcid.org/0009-0004-4454-6053Kodi Rider18Arpita Roy19https://orcid.org/0000-0001-8127-5775Ashley Baker20https://orcid.org/0000-0002-6525-7013Jerry Edelstein21Chris Smith22Josh Walawender23https://orcid.org/0000-0002-6092-8295Byeong-Cheol Lee24https://orcid.org/0000-0002-2783-0755Yu-Juan Liu25https://orcid.org/0009-0008-3430-1027Joshua N. Winn26https://orcid.org/0000-0002-4265-047XKorea Astronomy and Space Science Institute , 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of Korea; Institute for Astronomy, University of Hawai‘i , 2680 Woodlawn Drive, Honolulu, HI 96822, USA; CAS Key Laboratory of Optical Astronomy , National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of ChinaInstitute for Astronomy, University of Hawai‘i , 2680 Woodlawn Drive, Honolulu, HI 96822, USADepartment of Astronomy, California Institute of Technology , Pasadena, CA 91125, USAJet Propulsion Laboratory, California Institute of Technology , 4800 Oak Grove Drive, Pasadena, CA 91109, USADepartment of Astronomy, University of California Berkeley , Berkeley, CA 94720, USA; Centre for Astrophysics, University of Southern Queensland , Toowoomba, QLD, AustraliaNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanCenter for Computational Astrophysics, Flatiron Institute , 162 Fifth Avenue, New York, NY 10010, USANASA Exoplanet Science Institute/Caltech-IPAC , MC 314-6, 1200 E. California Boulevard, Pasadena, CA 91125, USADepartment of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology , Cambridge, MA 02139, USA; Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USADepartment of Physics & Astronomy, University of California Los Angeles , Los Angeles, CA 90095, USADepartment of Astronomy, California Institute of Technology , Pasadena, CA 91125, USADepartment of Astronomy, California Institute of Technology , Pasadena, CA 91125, USADepartment of Physics & Astronomy, University of California Los Angeles , Los Angeles, CA 90095, USADepartment of Physics & Astronomy, University of California Los Angeles , Los Angeles, CA 90095, USAInstitute for Astronomy, University of Hawai‘i , 2680 Woodlawn Drive, Honolulu, HI 96822, USADepartment of Physics & Astronomy, University of California Irvine , Irvine, CA 92697, USASubdepartment of Astrophysics, Department of Physics, University of Oxford , Oxford OX1 3RH, UKCaltech Optical Observatories , Pasadena, CA 91125, USASpace Sciences Laboratory, University of California Berkeley , Berkeley, CA 94720, USAAstrophysics & Space Institute , Schmidt Sciences, New York, NY 10011, USACaltech Optical Observatories , Pasadena, CA 91125, USASpace Sciences Laboratory, University of California Berkeley , Berkeley, CA 94720, USASpace Sciences Laboratory, University of California Berkeley , Berkeley, CA 94720, USAW. M. Keck Observatory , 65-1120 Mamalahoa Highway, Waimea, HI 96743, USAKorea Astronomy and Space Science Institute , 776 Daedeok-daero, Yuseong-gu, Daejeon 34055, Republic of KoreaCAS Key Laboratory of Optical Astronomy , National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of ChinaDepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USAWe report an observation of the Rossiter–McLaughlin (RM) effect of the transiting planet HD 93963 Ac, a mini-Neptune planet orbiting a G0-type star with an orbital period of P _c  = 3.65 days, accompanied by an inner super-Earth planet with P _b  = 1.04 days. We observed a full transit of planet c on 2024 May 3 UT with the Keck/Keck Planet Finder. The observed RM effect has an amplitude of ∼1 m s ^−1 and implies a sky-projected obliquity of $\lambda =1{4}_{-19}^{+17}$ degrees for HD 93963 Ac. Our dynamical analysis suggests that the two inner planets are likely well aligned with the stellar spin, to within a few degrees, thus allowing both to transit. Along with WASP-47, 55 Cnc, and HD 3167, HD 93963 is the fourth planetary system with an ultrashort-period planet and obliquity measurement(s) of any planet(s) in the system. HD 93963, WASP-47, and 55 Cnc favor largely coplanar orbital architectures, whereas HD 3167 has been reported to have a large mutual inclination (∼100°) between its transiting planets b and c. In this configuration, the probability that both planets transit is low. Moreover, one planet would quickly evolve to be nontransiting due to nodal precession. Future missions such as ESO/PLATO should detect the resulting transit duration variations. We encourage additional obliquity measurements of the HD 3167 system to better constrain its orbital architecture.https://doi.org/10.3847/1538-3881/addab9ExoplanetsMini NeptunesSuper EarthsExoplanet dynamics
spellingShingle Huan-Yu Teng
Fei Dai
Andrew W. Howard
Samuel Halverson
Howard Isaacson
Eiichiro Kokubo
Ryan A. Rubenzahl
Benjamin Fulton
Aaron Householder
Jack Lubin
Steven Giacalone
Luke Handley
Judah Van Zandt
Erik A. Petigura
J. M. Joel Ong
Pranav Premnath
Haochuan Yu
Steven R. Gibson
Kodi Rider
Arpita Roy
Ashley Baker
Jerry Edelstein
Chris Smith
Josh Walawender
Byeong-Cheol Lee
Yu-Juan Liu
Joshua N. Winn
Stellar Obliquity of the Ultra-short-period Planet System HD 93963
The Astronomical Journal
Exoplanets
Mini Neptunes
Super Earths
Exoplanet dynamics
title Stellar Obliquity of the Ultra-short-period Planet System HD 93963
title_full Stellar Obliquity of the Ultra-short-period Planet System HD 93963
title_fullStr Stellar Obliquity of the Ultra-short-period Planet System HD 93963
title_full_unstemmed Stellar Obliquity of the Ultra-short-period Planet System HD 93963
title_short Stellar Obliquity of the Ultra-short-period Planet System HD 93963
title_sort stellar obliquity of the ultra short period planet system hd 93963
topic Exoplanets
Mini Neptunes
Super Earths
Exoplanet dynamics
url https://doi.org/10.3847/1538-3881/addab9
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