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Constraints on the Obliquities of Kepler Planet-hosting Stars

Winn, Joshua N. and Petigura, Erik A. and Morton, Timothy D. and Weiss, Lauren M. and Dai, Fei and Schlaufman, Kevin C. and Howard, Andrew W. and Isaacson, Howard and Marcy, Geoffrey W. and Justesen, Anders Bo and Albrecht, Simon (2017) Constraints on the Obliquities of Kepler Planet-hosting Stars. Astronomical Journal, 154 (6). Art. No. 270. ISSN 1538-3881.

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Stars with hot Jupiters have obliquities ranging from 0° to 180°, but relatively little is known about the obliquities of stars with smaller planets. Using data from the California-Kepler Survey, we investigate the obliquities of stars with planets spanning a wide range of sizes, most of which are smaller than Neptune. First, we identify 156 planet hosts for which measurements of the projected rotation velocity (ν sin i) and rotation period are both available. By combining estimates of v and ν sin i, we find nearly all the stars to be compatible with high inclination, and hence, low obliquity (≾20°). Second, we focus on a sample of 159 hot stars (T_(eff) > 6000 K) for which ν sin i is available but not necessarily the rotation period. We find six stars for which ν sin i is anomalously low, an indicator of high obliquity. Half of these have hot Jupiters, even though only 3% of the stars that were searched have hot Jupiters. We also compare the ν sin i distribution of the hot stars with planets to that of 83 control stars selected without prior knowledge of planets. The mean ν sin i of the control stars is lower than that of the planet hosts by a factor of approximately π/4, as one would expect if the planet hosts have low obliquities. All these findings suggest that the Kepler planet-hosting stars generally have low obliquities, with the exception of hot stars with hot Jupiters.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Winn, Joshua N.0000-0002-4265-047X
Petigura, Erik A.0000-0003-0967-2893
Morton, Timothy D.0000-0002-8537-5711
Weiss, Lauren M.0000-0002-3725-3058
Dai, Fei0000-0002-8958-0683
Schlaufman, Kevin C.0000-0001-5761-6779
Howard, Andrew W.0000-0001-8638-0320
Isaacson, Howard0000-0002-0531-1073
Marcy, Geoffrey W.0000-0002-2909-0113
Additional Information:© 2017 The American Astronomical Society. Received 2017 September 5; revised 2017 October 6; accepted 2017 October 12; published 2017 December 1. We are grateful to the other CKS team members, and the NASA Kepler team, for producing the database upon which this study is based. E.A.P. acknowledges support from Hubble Fellowship grant HST-HF2-51365.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. for NASA under contract NAS 5-26555. S.A. and A.B.J. acknowledge support from the Danish Council for Independent Research, through a DFF Sapere Aude Starting grant No. 4181-00487B. The authors also wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Group:Astronomy Department
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF2-51365.001-A
NASANAS 5-26555
Danish Council for Independent Research4181-00487B
Subject Keywords:planet–star interactions – planets and satellites: formation – stars: rotation
Issue or Number:6
Record Number:CaltechAUTHORS:20171201-152749195
Persistent URL:
Official Citation:Joshua N. Winn et al 2017 AJ 154 270
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83638
Deposited By: Tony Diaz
Deposited On:02 Dec 2017 04:42
Last Modified:03 Oct 2019 19:08

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