The Warm Neptunes around HD 106315 Have Low Stellar Obliquities

Zhou, George ORCID: and Rodriguez, Joseph E. and Vanderburg, Andrew and Quinn, Samuel N. and Irwin, Jonathan and Huang, Chelsea X. ORCID: and Latham, David W. and Bieryla, Allyson and Esquerdo, Gilbert A. and Berlind, Perry and Calkins, Michael L. (2018) The Warm Neptunes around HD 106315 Have Low Stellar Obliquities. The Astronomical Journal, 156 (3):93. pp. 1-10. ISSN 0004-6256

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We present the obliquity of the warm Neptune HD 106315c measured via a series of spectroscopic transit observations. HD 106315c is a 4.4 R Earth warm Neptune orbiting a moderately rotating late F star with a period of 21.05 days. HD 106315 also hosts a 2.5 R Earth super-Earth on a 9.55 day orbit. Our Doppler tomographic analyses of four transits observed by the Magellan/MIKE, HARPS, and TRES facilities find HD 106315c to be in a low stellar obliquity orbit, consistent with being well aligned with the spin axis of the host star at . We suggest, via dynamical N-body simulations, that the two planets in the system must be coplanar, and thus are both well aligned with the host star. HD 106315 is only the fourth warm Neptune system with obliquities measured. All warm Neptune systems have been found in well aligned geometries, consistent with the interpretation that these systems are formed in situ in the inner protoplanetary disk, and also consistent with the majority of Kepler multi-planet systems that are in low obliquity orbits. With a transit depth of 1.02 mmag, HD 106315c is among the smallest planets to have been detected in transit spectroscopy, and we discuss its detection in the context of TESS and the next generations of spectrographs.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 08 Feb 2022 04:28
Last Modified: 14 Feb 2022 00:48
Uncontrolled Keywords: planets and satellites: dynamical evolution and stability; planets and satellites: individual: HD 106315; Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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