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Evidence of a Sub-Saturn around EPIC 211945201

Chakraborty, Abhijit and Roy, Arpita and Sharma, Rishikesh and Mahadevan, Suvrath and Chaturvedi, Priyanka and Prasad, Neelam J. S. S. V. and Anandarao, B. G. (2018) Evidence of a Sub-Saturn around EPIC 211945201. Astronomical Journal, 156 (1). Art. No. 3. ISSN 1538-3881. doi:10.3847/1538-3881/aac436.

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We report here strong evidence for a sub-Saturn around EPIC 211945201 and confirm its planetary nature. EPIC 211945201b was found to be a planetary candidate from K2 photometry in Campaigns 5 and 16, transiting a bright star (V_(mag) = 10.15, G0 spectral type) in a 19.492 day orbit. However, the photometric data combined with false positive probability calculations using VESPA was not sufficient to confirm the planetary scenario. Here, we present high-resolution spectroscopic follow up of the target using the PARAS spectrograph (19 radial velocity observations) over a time baseline of 420 days. We conclusively rule out the possibility of an eclipsing binary system and confirm the 2σ detection of a sub-Saturn planet. The confirmed planet has a radius of 6.12 ± 0.1 R⊕, and a mass of 27^(+14)_(-12.6) M⊕. We also place an upper limit on the mass (within the 3σ confidence interval) at 42 M⊕ above the nominal value. This results in the Saturn-like density of 0.65^(+0.34)_(-0.30) g cm^(-3). Based on the mass and radius, we provide a preliminary model-dependent estimate that the heavy element content is 60%–70% of the total mass. This detection is important as it adds to a sparse catalog of confirmed exoplanets with masses between 10 and 70 M⊕ and radii between 4 and 8 R⊕, whose masses and radii are measured to a precision of 50% or better (only 23 including this work).

Item Type:Article
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URLURL TypeDescription Paper
Chakraborty, Abhijit0000-0002-3815-8407
Roy, Arpita0000-0001-8127-5775
Sharma, Rishikesh0000-0001-8983-5300
Mahadevan, Suvrath0000-0001-9596-7983
Additional Information:© 2018 The American Astronomical Society. Received 2018 April 9; revised 2018 May 8; accepted 2018 May 9; published 2018 June 8. The PARAS spectrograph is fully funded and being supported by Physical Research Laboratory (PRL), which is part of Department of Space, Government of India. We would like to thank Director, PRL for his support. We acknowledge the help from Vishal Shah, Kapil Kumar, Kevikumar Lad, Ashirbad Nayak and Mount Abu Observatory staff for their support during observations. We acknowledge the use of SIMBAD database operated at the CDS, Strasbourg, France. We also acknowledge the support from ExoFOP users, who willingly share the follow-up observational data with the community. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program; and the Extrasolar Planets Encyclopaedia ( We are also thankful to Francesco Pepe (Geneva Observatory) for providing G2 stellar mask which is used for RV reduction. Software: VESPA (Morton 2012, Morton 2015), PARAS PIPELINE (Chakraborty et al. 2014), PARAS SPEC (Chaturvedi et al. 2016a, 2016b), ISOCHRONES (Morton 2015), PYANETI (Barragán et al. 2016, 2017).
Funding AgencyGrant Number
Physical Research LaboratoryUNSPECIFIED
Department of Space (India)UNSPECIFIED
Subject Keywords:planetary systems – stars: individual (EPIC 211945201) – techniques: photometric – techniques: radial velocities
Issue or Number:1
Record Number:CaltechAUTHORS:20180608-142416162
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Official Citation:Abhijit Chakraborty et al 2018 AJ 156 3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86935
Deposited By: Tony Diaz
Deposited On:08 Jun 2018 21:39
Last Modified:15 Nov 2021 20:43

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