An ultra-short-period super-Earth with an extremely high density and an outer companion
We present the discovery and characterization of a new multi-planetary system around the Sun-like star K2-360 (EPIC 201595106). K2-360 was first identified in K2 photometry as the host of an ultra-short-period (USP) planet candidate with a period of 0.88 d. We obtained follow-up transit photometry, confirming the star as the host of the signal. High precision radial velocity measurements from HARPS and HARPS-N confirm the transiting USP planet and reveal the existence of an outer (non-transiting) planet with an orbital period of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>∼</mml:mo></mml:math> 10 d. We measure a mass of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>7.67</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.75</mml:mn></mml:mrow> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>M</mml:mi> <mml:mo>⊕</mml:mo></mml:msub> </mml:math> and a radius of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.57</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.08</mml:mn></mml:mrow> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi> <mml:mo>⊕</mml:mo></mml:msub> </mml:math> for the transiting planet, yielding a high mean density of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>11</mml:mn> <mml:mo>±</mml:mo> <mml:mn>2</mml:mn></mml:mrow> </mml:math> g <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mtext>cm</mml:mtext> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>3</mml:mn></mml:mrow> </mml:msup> </mml:math> , making it the densest well-characterized USP super-Earth discovered to date. We measure a minimum mass of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>15.2</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1.8</mml:mn></mml:mrow> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>M</mml:mi> <mml:mo>⊕</mml:mo></mml:msub> </mml:math> for the outer planet, and explore a migration formation pathway via the von Zeipel-Kozai-Lidov (ZKL) mechanism and tidal dissipation.
Authors
- H. J. Deeg (ORCID: https://orcid.org/0000-0003-0047-4241)
- Simon Albrecht (ORCID: https://orcid.org/0000-0003-1762-8235)
- R. Luque (ORCID: https://orcid.org/0000-0002-4671-2957)
- Yoichi Tamura (ORCID: https://orcid.org/0000-0003-4807-8117)
- Akihiko Fukui (ORCID: https://orcid.org/0000-0002-4909-5763)
- Ε. Πάλλη (ORCID: https://orcid.org/0000-0003-0987-1593)
- D. Gandolfi (ORCID: https://orcid.org/0000-0001-8627-9628)
- Mahesh Herath
- Alessandro A. Trani (ORCID: https://orcid.org/0000-0001-5371-3432)
- Fei Dai (ORCID: https://orcid.org/0000-0002-7651-8549)
- J. Korth (ORCID: https://orcid.org/0000-0002-0076-6239)
- A. P. Hatzes (ORCID: https://orcid.org/0000-0002-3404-8358)
- John H. Livingston (ORCID: https://orcid.org/0000-0002-4881-3620)
- Teruyuki Hirano (ORCID: https://orcid.org/0000-0003-3618-7535)
- Jerome de Leon (ORCID: https://orcid.org/0000-0002-6424-3410)
- Vincent Van Eylen (ORCID: https://orcid.org/0000-0001-5542-8870)
- C. Hellier (ORCID: https://orcid.org/0000-0002-3439-1439)
- Oscar Barragán (ORCID: https://orcid.org/0000-0003-0563-0493)
- Norio Narita (ORCID: https://orcid.org/0000-0001-8511-2981)
- G. Nowak (ORCID: https://orcid.org/0000-0002-7031-7754)
- Malcolm Fridlund
Institutions
- California Institute of Technology (US)
- Planetary Science Institute (US)
- University of Hawaii System (US)
- Okinawa Institute of Science and Technology Graduate University (JP)
- Universidad de La Laguna (ES)
- Lund University (SE)
- The Graduate University for Advanced Studies, SOKENDAI (JP)
- Aarhus University (DK)
- Nicolaus Copernicus University (PL)
- University of Oxford (GB)
- University of Chicago (US)
- Astrobiology Center (JP)
- Instituto de Astrofísica de Canarias (ES)
- Nicolaus Copernicus Astronomical Center (PL)
- Tokyo Metropolitan Komaba High School (JP)
- Thüringer Landessternwarte Tautenburg (DE)
- National Astronomical Observatory of Japan (JP)
- University College London (GB)
- McGill University (CA)
- University of Turin (IT)
- Keele University (GB)
- Chalmers University of Technology (SE)
- The University of Tokyo (JP)
Publication Details
- Journal
- Scientific Reports
- Published
- 2024-11-08
- DOI
- https://doi.org/10.1038/s41598-024-76490-y
- Citations
- 1
- Primary Topic
- Astro and Planetary Science
- Type
- article
- Field-Weighted Citation Impact
- 0.33
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- NASA Exoplanet Science Institute
- Vetenskapsrådet
- Ministerio de Ciencia e Innovación
- Uniwersytet Mikolaja Kopernika w Toruniu
- Ames Research Center
- Science Mission Directorate
- Science and Technology Facilities Council
- Japan Society for the Promotion of Science
- European Regional Development Fund
- Agencia Estatal de Investigación
- Core Research for Evolutional Science and Technology