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Title: The NASA-UC-UH Eta-Earth program. IV. A low-mass planet orbiting an M dwarf 3.6 PC from Earth

We report the discovery of a low-mass planet orbiting Gl 15 A based on radial velocities from the Eta-Earth Survey using HIRES at Keck Observatory. Gl 15 Ab is a planet with minimum mass Msin i = 5.35 ± 0.75 M {sub ⊕}, orbital period P = 11.4433 ± 0.0016 days, and an orbit that is consistent with circular. We characterize the host star using a variety of techniques. Photometric observations at Fairborn Observatory show no evidence for rotational modulation of spots at the orbital period to a limit of ∼0.1 mmag, thus supporting the existence of the planet. We detect a second RV signal with a period of 44 days that we attribute to rotational modulation of stellar surface features, as confirmed by optical photometry and the Ca II H and K activity indicator. Using infrared spectroscopy from Palomar-TripleSpec, we measure an M2 V spectral type and a sub-solar metallicity ([M/H] = –0.22, [Fe/H] = –0.32). We measure a stellar radius of 0.3863 ± 0.0021 R {sub ☉} based on interferometry from CHARA.
Authors:
 [1] ; ;  [2] ; ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  2. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
  3. Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
  4. Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States)
  5. Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Boulevard, Box 9501, Nashville, TN 37209 (United States)
  6. NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States)
  7. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)
  8. Center for Planetary Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22370487
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; INFRARED SPECTRA; INTERFEROMETRY; MASS; METALLICITY; MODULATION; NASA; ORBITS; PHOTOMETRY; PLANETS; RADIAL VELOCITY; STARS; SURFACES