The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b

Gudmundur Stefansson; Suvrath Mahadevan; Marissa Maney; Joe P. Ninan; Paul Robertson; Jayadev Rajagopal; Flynn Haase; Lori Allen; Eric B. Ford; Joshua Winn; Angie Wolfgang; Rebekah I. Dawson; John Wisniewski; Chad F. Bender; Caleb Cañas; William Cochran; Scott A. Diddams; Connor Fredrick; Samuel Halverson; Fred Hearty; Leslie Hebb; Shubham Kanodia; Eric Levi; Andrew J. Metcalf; Andrew Monson; Lawrence Ramsey; Arpita Roy; Christian Schwab; Ryan Terrien; Jason T. Wright

doi:10.3847/1538-3881/abb13a

The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b

Gudmundur Stefansson, Suvrath Mahadevan, Marissa Maney, Joe P. Ninan, Paul Robertson, Jayadev Rajagopal, Flynn Haase, Lori Allen, Eric B. Ford, Joshua Winn, Angie Wolfgang, Rebekah I. Dawson, John Wisniewski, Chad F. Bender, Caleb Cañas, William Cochran, Scott A. Diddams, Connor Fredrick, Samuel Halverson, Fred HeartyLeslie Hebb, Shubham Kanodia, Eric Levi, Andrew J. Metcalf, Andrew Monson, Lawrence Ramsey, Arpita Roy, Christian Schwab, Ryan Terrien, Jason T. Wright

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Abstract

Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 ± 0.12 R☉ and 24.5_-⁺_5.2^5.7 M_Å. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 ± 0.05. The sky-projected stellar obliquity is λ = 3° ± 16°, compatible with spin-orbit alignment, in contrast to other “hot Neptunes” that have been studied around older stars.

Original language	English (US)
Article number	abb13a
Journal	Astronomical Journal
Volume	160
Issue number	4
DOIs	https://doi.org/10.3847/1538-3881/abb13a
State	Published - Oct 2020

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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Stefansson, G., Mahadevan, S., Maney, M., Ninan, J. P., Robertson, P., Rajagopal, J., Haase, F., Allen, L., Ford, E. B., Winn, J., Wolfgang, A., Dawson, R. I., Wisniewski, J., Bender, C. F., Cañas, C., Cochran, W., Diddams, S. A., Fredrick, C., Halverson, S., ... Wright, J. T. (2020). The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b. Astronomical Journal, 160(4), Article abb13a. https://doi.org/10.3847/1538-3881/abb13a

@article{83997ea1d4e743899f1a5f00f0ee8403,

title = "The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b",

abstract = "Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 ± 0.12 R☉ and 24.5-+5.25.7 M{\AA}. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 ± 0.05. The sky-projected stellar obliquity is λ = 3° ± 16°, compatible with spin-orbit alignment, in contrast to other “hot Neptunes” that have been studied around older stars.",

author = "Gudmundur Stefansson and Suvrath Mahadevan and Marissa Maney and Ninan, {Joe P.} and Paul Robertson and Jayadev Rajagopal and Flynn Haase and Lori Allen and Ford, {Eric B.} and Joshua Winn and Angie Wolfgang and Dawson, {Rebekah I.} and John Wisniewski and Bender, {Chad F.} and Caleb Ca{\~n}as and William Cochran and Diddams, {Scott A.} and Connor Fredrick and Samuel Halverson and Fred Hearty and Leslie Hebb and Shubham Kanodia and Eric Levi and Metcalf, {Andrew J.} and Andrew Monson and Lawrence Ramsey and Arpita Roy and Christian Schwab and Ryan Terrien and Wright, {Jason T.}",

year = "2020",

month = oct,

doi = "10.3847/1538-3881/abb13a",

language = "English (US)",

volume = "160",

journal = "Astronomical Journal",

issn = "0004-6256",

publisher = "American Astronomical Society",

number = "4",

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Stefansson, G, Mahadevan, S, Maney, M, Ninan, JP, Robertson, P, Rajagopal, J, Haase, F, Allen, L, Ford, EB, Winn, J, Wolfgang, A, Dawson, RI, Wisniewski, J, Bender, CF, Cañas, C, Cochran, W, Diddams, SA, Fredrick, C, Halverson, S, Hearty, F, Hebb, L, Kanodia, S, Levi, E, Metcalf, AJ, Monson, A, Ramsey, L, Roy, A, Schwab, C, Terrien, R & Wright, JT 2020, 'The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b', Astronomical Journal, vol. 160, no. 4, abb13a. https://doi.org/10.3847/1538-3881/abb13a

TY - JOUR

T1 - The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b

AU - Stefansson, Gudmundur

AU - Mahadevan, Suvrath

AU - Maney, Marissa

AU - Ninan, Joe P.

AU - Robertson, Paul

AU - Rajagopal, Jayadev

AU - Haase, Flynn

AU - Allen, Lori

AU - Ford, Eric B.

AU - Winn, Joshua

AU - Wolfgang, Angie

AU - Dawson, Rebekah I.

AU - Wisniewski, John

AU - Bender, Chad F.

AU - Cañas, Caleb

AU - Cochran, William

AU - Diddams, Scott A.

AU - Fredrick, Connor

AU - Halverson, Samuel

AU - Hearty, Fred

AU - Hebb, Leslie

AU - Kanodia, Shubham

AU - Levi, Eric

AU - Metcalf, Andrew J.

AU - Monson, Andrew

AU - Ramsey, Lawrence

AU - Roy, Arpita

AU - Schwab, Christian

AU - Terrien, Ryan

AU - Wright, Jason T.

PY - 2020/10

Y1 - 2020/10

N2 - Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 ± 0.12 R☉ and 24.5-+5.25.7 MÅ. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 ± 0.05. The sky-projected stellar obliquity is λ = 3° ± 16°, compatible with spin-orbit alignment, in contrast to other “hot Neptunes” that have been studied around older stars.

AB - Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 ± 0.12 R☉ and 24.5-+5.25.7 MÅ. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 ± 0.05. The sky-projected stellar obliquity is λ = 3° ± 16°, compatible with spin-orbit alignment, in contrast to other “hot Neptunes” that have been studied around older stars.

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DO - 10.3847/1538-3881/abb13a

M3 - Article

AN - SCOPUS:85092517825

SN - 0004-6256

VL - 160

JO - Astronomical Journal

JF - Astronomical Journal

IS - 4

M1 - abb13a

ER -

The habitable zone planet finder reveals a high mass and low obliquity for the young neptune k2-25b

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