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Post Info TOPIC: Gliese 221


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Gliese 221
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Title: Two planetary companions around the K7 dwarf GJ 221 : a hot super-Earth and a candidate in the sub-Saturn desert range
Authors: Pamela Arriagada, Guillem Anglada-Escudé, R. Paul Butler, Jeffrey D. Crane, Stephen A. Shectman, Ian Thompson, Sebastian Wende, Dante Minniti

We report two low mass companions orbiting the nearby K7 dwarf GJ 221 that have emerged from re-analysing 4.4 years 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 earth masses (GJ 221b), falling in a mass range where very few planet candidates have been found (sub-Saturn desert). The addition of 17 PFS observations allow the confident detection of a second low mass companion (6.5 earth masses) in a hot orbit (3.87 days 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.

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