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Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars II: Planetary Systems Observed During Campaigns 1-7
- Source :
- Astronomical Journal, vol 154, iss 5, The Astronomical Journal, vol 154, iss 5
- Publication Year :
- 2017
- Publisher :
- American Astronomical Society, 2017.
-
Abstract
- We recently used near-infrared spectroscopy to improve the characterization of 76 low-mass stars around which K2 had detected 79 candidate transiting planets. Thirty of these worlds were new discoveries that have not previously been published. We calculate the false positive probabilities that the transit-like signals are actually caused by non-planetary astrophysical phenomena and reject five new transit-like events and three previously reported events as false positives. We also statistically validate 18 planets (eight of which were previously unpublished), confirm the earlier validation of 21 planets, and announce 17 newly discovered planet candidates. Revising the properties of the associated planet candidates based on the updated host star characteristics and refitting the transit photometry, we find that our sample contains 20 planets or planet candidates with radii smaller than 1.25 Earth radii, 20 super-Earths (1.25-2 Earth radii), 20 small Neptunes (2-4 Earth radii), three large Neptunes (4-6 Earth radii), and eight giant planets (> 6 Earth radii). Most of these planets are highly irradiated, but EPIC 206209135.04 (K2-72e, Rp = 1.29 (-0.13/+0.14) Earth radii), EPIC 211988320.01 (Rp = 2.86 (-0.15/+0.16) Earth radii), and EPIC 212690867.01 (Rp = 2.20 (-0.18/+0.19) Earth radii) orbit within optimistic habitable zone boundaries set by the "recent Venus" inner limit and the "early Mars" outer limit. In total, our planet sample includes eight moderately-irradiated 1.5-3 Earth radius planet candidates (Fp < 20 F_Earth) orbiting brighter stars (Ks < 11) that are well-suited for atmospheric investigations with Hubble, Spitzer, and/or the James Webb Space Telescope. Five validated planets orbit relatively bright stars (Kp < 12.5) and are expected to yield radial velocity semi-amplitudes of at least 2 m/s.<br />26 pages, 13 figures, 4, tables. Submitted to ApJ. The associated follow-up observations and vetting plots will be posted to the ExoFOP-K2 website (https://exofop.ipac.caltech.edu/k2/)
- Subjects :
- astro-ph.SR
010504 meteorology & atmospheric sciences
fundamental parameters [stars]
FOS: Physical sciences
Astrophysics::Cosmology and Extragalactic Astrophysics
Astronomy & Astrophysics
01 natural sciences
Earth radius
fundamental parameters [planets and satellites]
Planet
0103 physical sciences
low-mass [stars]
Transit (astronomy)
010303 astronomy & astrophysics
planetary systems
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Earth and Planetary Astrophysics (astro-ph.EP)
Physics
Astronomy
Astronomy and Astrophysics
Planetary system
Radial velocity
Stars
Photometry (astronomy)
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
astro-ph.EP
late-type [stars]
spectroscopic [techniques]
Astrophysics::Earth and Planetary Astrophysics
Circumstellar habitable zone
Astronomical and Space Sciences
Astrophysics - Earth and Planetary Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Astronomical Journal, vol 154, iss 5, The Astronomical Journal, vol 154, iss 5
- Accession number :
- edsair.doi.dedup.....1d37b79494487088fa6aaced07395382