TY - JOUR
T1 - The Warm Neptune GJ 3470b Has a Polar Orbit
AU - Stefànsson, Gudmundur
AU - Mahadevan, Suvrath
AU - Petrovich, Cristobal
AU - Winn, Joshua N.
AU - Kanodia, Shubham
AU - Millholland, Sarah C.
AU - Maney, Marissa
AU - Cañas, Caleb I.
AU - Wisniewski, John
AU - Robertson, Paul
AU - Ninan, Joe P.
AU - Ford, Eric B.
AU - Bender, Chad F.
AU - Blake, Cullen H.
AU - Cegla, Heather
AU - Cochran, William D.
AU - Diddams, Scott A.
AU - Dong, Jiayin
AU - Endl, Michael
AU - Fredrick, Connor
AU - Halverson, Samuel
AU - Hearty, Fred
AU - Hebb, Leslie
AU - Hirano, Teruyuki
AU - Lin, Andrea S.J.
AU - Logsdon, Sarah E.
AU - Lubar, Emily
AU - McElwain, Michael W.
AU - Metcalf, Andrew J.
AU - Monson, Andrew
AU - Rajagopal, Jayadev
AU - Ramsey, Lawrence W.
AU - Roy, Arpita
AU - Schwab, Christian
AU - Schweiker, Heidi
AU - Terrien, Ryan C.
AU - Wright, Jason T.
N1 - Funding Information:
We thank the anonymous referee for their thoughtful reading and suggestions, which made for a stronger manuscript. G.K.S. thanks Luke Bouma and Molly Kosiarek for helpful discussions. Data presented were obtained by the NEID spectrograph built by Penn State University and operated at the WIYN Observatory by NOIRLab, under the NN-EXPLORE partnership of the National Aeronautics and Space Administration and the National Science Foundation. Based in part on observations at the Kitt Peak National Observatory, NSF's NOIRLab (Prop. ID 2020B-0075; PI: G. Stefansson), managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. WIYN is a joint facility of the University of Wisconsin—Madison, Indiana University, NSF's NOIRLab, the Pennsylvania State University, Purdue University, University of California, Irvine, and the University of Missouri. The authors are honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham. Data presented herein were obtained at the WIYN Observatory from telescope time allocated to NN-EXPLORE through the scientific partnership of the National Aeronautics and Space Administration, the National Science Foundation, and the National Optical Astronomy Observatory. C.P. acknowledges support from ANID Millennium Science Initiative-ICN12_009, CATA-Basal AFB-170002, ANID BASAL project FB210003, FONDECYT Regular grant 1210425, and ANID+REC Convocatoria Nacional subvencion a la instalacion en la Academia convocatoria 2020 PAI77200076.
Funding Information:
These results are based on observations obtained with the Habitable-zone Planet Finder Spectrograph on the HET. We acknowledge support from NSF grants AST 1006676, AST 1126413, AST 1310875, and AST 1310885, and the NASA Astrobiology Institute (NNA09DA76A) in our pursuit of precision radial velocities in the NIR. We acknowledge support from the Heising-Simons Foundation via grant 2017-0494. This research was conducted in part under NSF grants AST-2108493, AST-2108512, AST-2108569, and AST-2108801 in support of the HPF Guaranteed Time Observations survey. The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universitat Munchen, and Georg-August Universitat Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly. The HET collaboration acknowledges the support and resources from the Texas Advanced Computing Center. We thank the resident astronomers and telescope operators at the HET for the skillful execution of our observations with HPF.
Funding Information:
This work was partially supported by funding from the Center for Exoplanets and Habitable Worlds. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. C.I.C. acknowledges support by NASA Headquarters under the NASA Earth and Space Science Fellowship Program through grants 80NSSC18K1114. This work was performed for the Jet Propulsion Laboratory, California Institute of Technology, sponsored by the United States Government under the Prime Contract 80NM0018D0004 between Caltech and NASA. We acknowledge support from NSF grants AST-1909506, AST-190950, AST-1910954, and AST-1907622, and the Research Corporation for precision photometric observations with diffuser-assisted photometry. Computations for this research were performed at the Pennsylvania State University's Institute for Computational & Data Sciences (ICDS). A portion of this work was enabled by support from the Mt Cuba Astronomical Foundation.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - The warm Neptune GJ 3470b transits a nearby (d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak Observatory, we model the classical Rossiter-McLaughlin effect, yielding a sky-projected obliquity of λ=98-12+15° and a vsini=0.85-0.33+0.27kms-1 . Leveraging information about the rotation period and size of the host star, our analysis yields a true obliquity of ψ=95-8+9°, revealing that GJ 3470b is on a polar orbit. Using radial velocities from HIRES, HARPS, and the Habitable-zone Planet Finder, we show that the data are compatible with a long-term radial velocity (RV) slope of γ=-0.0022±0.0011ms-1day-1 over a baseline of 12.9 yr. If the RV slope is due to acceleration from another companion in the system, we show that such a companion is capable of explaining the polar and mildly eccentric orbit of GJ 3470b using two different secular excitation models. The existence of an outer companion can be further constrained with additional RV observations, Gaia astrometry, and future high-contrast imaging observations. Lastly, we show that tidal heating from GJ 3470b's mild eccentricity has most likely inflated the radius of GJ 3470b by a factor of ∼1.5-1.7, which could help account for its evaporating atmosphere.
AB - The warm Neptune GJ 3470b transits a nearby (d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak Observatory, we model the classical Rossiter-McLaughlin effect, yielding a sky-projected obliquity of λ=98-12+15° and a vsini=0.85-0.33+0.27kms-1 . Leveraging information about the rotation period and size of the host star, our analysis yields a true obliquity of ψ=95-8+9°, revealing that GJ 3470b is on a polar orbit. Using radial velocities from HIRES, HARPS, and the Habitable-zone Planet Finder, we show that the data are compatible with a long-term radial velocity (RV) slope of γ=-0.0022±0.0011ms-1day-1 over a baseline of 12.9 yr. If the RV slope is due to acceleration from another companion in the system, we show that such a companion is capable of explaining the polar and mildly eccentric orbit of GJ 3470b using two different secular excitation models. The existence of an outer companion can be further constrained with additional RV observations, Gaia astrometry, and future high-contrast imaging observations. Lastly, we show that tidal heating from GJ 3470b's mild eccentricity has most likely inflated the radius of GJ 3470b by a factor of ∼1.5-1.7, which could help account for its evaporating atmosphere.
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U2 - 10.3847/2041-8213/ac6e3c
DO - 10.3847/2041-8213/ac6e3c
M3 - Article
AN - SCOPUS:85131416896
SN - 2041-8205
VL - 931
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L15
ER -