Two planetary companions around the K7 dwarf GJ 221: A hot super-earth and a candidate in the sub-saturn desert range

Pamela Arriagada, Guillem Anglada-Escudé, R. Paul Butler, Jeffrey D. Crane, Stephen A. Shectman, Ian Thompson, Sebastian Wende, Dante Minniti

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

We report two low-mass companions orbiting the nearby K7 dwarf GJ 221 that have emerged from reanalyzing 4.4 yr of publicly available HARPS spectra complemented with 2 years of high-precision Doppler measurements with Magellan/PFS. The HARPS measurements alone contain the clear signal of a low-mass companion with a period of 125 days and a minimum mass of 53.2 M (GJ 221b), falling in a mass range where very few planet candidates have been found (sub-Saturn desert). The addition of 17 PFS observations allows the confident detection of a second low-mass companion (6.5 M ) in a hot orbit (3.87 day period, GJ 221c). Spectroscopic and photometric calibrations suggest that GJ 221 is slightly depleted ([Fe/H] ∼ -0.1) compared to the Sun, so the presence of two low-mass companions in the system confirms the trend that slightly reduced stellar metallicity does not prevent the formation of planets in the super-Earth to sub-Saturn mass regime.

Original languageEnglish
Article number42
JournalAstrophysical Journal
Volume771
Issue number1
DOIs
Publication statusPublished - 1 Jul 2013

Keywords

  • planetary systems
  • stars: individual (GJ 221, BD-061339)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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