The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b

被引：52

作者：

Stefansson, Gudmundur ^{[1
,2
,3
]}

Mahadevan, Suvrath ^{[1
,2
]}

Maney, Marissa ^{[1
]}

Ninan, Joe P. ^{[1
,2
]}

Robertson, Paul ^{[4
]}

Rajagopal, Jayadev ^{[5
]}

Haase, Flynn ^{[5
]}

Allen, Lori ^{[5
]}

Ford, Eric B. ^{[1
,2
,6
]}

Winn, Joshua ^{[3
]}

Wolfgang, Angie ^{[1
,2
]}

Dawson, Rebekah I. ^{[1
,2
]}

Wisniewski, John ^{[7
]}

Bender, Chad F. ^{[8
]}

Canas, Caleb ^{[1
,2
]}

Cochran, William ^{[9
,10
]}

Diddams, Scott A. ^{[11
,12
]}

Fredrick, Connor ^{[11
,12
]}

Halverson, Samuel ^{[13
]}

Hearty, Fred ^{[1
]}

Hebb, Leslie ^{[14
]}

Kanodia, Shubham ^{[1
,2
]}

Levi, Eric ^{[1
]}

Metcalf, Andrew J. ^{[11
,12
,15
]}

Monson, Andrew ^{[1
,2
]}

Ramsey, Lawrence ^{[1
,2
]}

Roy, Arpita ^{[16
]}

Schwab, Christian ^{[17
]}

Terrien, Ryan ^{[18
]}

Wright, Jason T. ^{[1
,2
]}

机构：

[1] Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, University Pk, PA 16802 USA

[2] Ctr Exoplanets & Habitable Worlds, University Pk, PA 16802 USA

[3] Princeton Univ, Dept Astrophys Sci, 4 Ivy Lane, Princeton, NJ 08540 USA

[4] Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA

[5] NSFs OIR Lab, 950 North Cherry Ave, Tucson, AZ 85719 USA

[6] Penn State Univ, Inst Computat & Data Sci, 203 Comp Bldg, University Pk, PA 16802 USA

[7] Univ Oklahoma, Homer L Dodge Dept Phys & Astron, 440 West Brooks St, Norman, OK 73019 USA

[8] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA

[9] Univ Texas Austin, McDonald Observ, Austin, TX 78712 USA

[10] Univ Texas Austin, Ctr Planetary Syst Habitabil, Austin, TX 78712 USA

[11] NIST, Div Time & Frequency, 325 Broadway, Boulder, CO 80305 USA

[12] Univ Colorado, Dept Phys, 2000 Colorado Ave, Boulder, CO 80309 USA

[13] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[14] Hobart & William Smith Coll, Dept Phys, 300 Pulteney St, Geneva, NY 14456 USA

[15] US Air Force, Space Vehicles Directorate, Res Lab, 3550 Aberdeen Ave SE, Kirtland AFB, NM 87117 USA

[16] CALTECH, 1200 East Calif Blvd, Pasadena, CA 91125 USA

[17] Macquarie Univ, Dept Phys & Astron, Balaclava Rd, N Ryde, NSW 2109, Australia

[18] Carleton Coll, Dept Phys & Astron, Northfield, MN 55057 USA

来源：

ASTRONOMICAL JOURNAL | 2020年 / 160卷 / 04期

基金：

美国国家航空航天局;

关键词：

Exoplanet astronomy; Exoplanet systems; Radial velocity; Exoplanet detection methods; Transit photometry; Photometry; Exoplanet formation; Mini Neptunes; Low mass stars; Near infrared astronomy; STELLAR ROTATION; GIANT PLANETS; HOT JUPITERS; SUPER-EARTHS; ORBIT; STARS; SPIN; SPECTROSCOPY; MISALIGNMENT; EXOPLANETS;

D O I：

10.3847/1538-3881/abb13a

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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-circle plus and 24.5(-5.2)(+5.7) M-circle plus. 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 lambda = 3 degrees +/- 16 degrees, compatible with spin-orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.

引用

页数：28

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