J/AJ/160/192 Photometry and RVs of K2-25b with HPF (Stefansson+, 2020)
The habitable zone planet finder reveals a high mass and low obliquity for the
young Neptune K2-25b.
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., Canas C., Cochran W.,
Diddams S.A., Fredrick C., Halverson S., Hearty F., Hebb L., Kanodia S.,
Levi E., Metcalf A.J., Monson A., Ramsey L., Roy A., Schwab C., Terrien R.,
Wright J.T.
<Astron. J., 160, 192 (2020)>
=2020AJ....160..192S 2020AJ....160..192S
ADC_Keywords: Exoplanets; Stars, dwarfs; Photometry, infrared; Radial velocities
Keywords: Exoplanet astronomy ; Exoplanet systems ; Radial velocity ;
Exoplanet detection methods ; Transit photometry ; Photometry ;
Exoplanet formation ; Mini Neptunes ; Low mass stars ;
Near infrared astronomy
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 600-800Myr 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±0.12R⊕ and
24.5-5.2+5.7M⊕. 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.
Description:
We obtained five transits of K2-25b using the Astrophysical Research
Consortium Telescope Imaging Camera (ARCTIC) imager on the 3.5m
Astrophysical Research Consortium (ARC) 3.5m Telescope at Apache Point
Observatory (APO) on the nights of UT 2017 September 17; 2019 January
4, 18, and 25; and 2019 February 1. All of the transit observations
were performed with the Engineered Diffuser available on ARCTIC, which
we designed specifically to enable very high precision photometric
observations. We used the Sloan Digital Sky Survey (SDSS) i' filter,
except on the night of 2019 January 18, when we used the SDSS z'
filter without the diffuser to minimize background Moon contamination.
We observed four transits of K2-25b using the Half-Degree Imager (HDI)
at the WIYN 0.9m telescope at Kitt Peak National Observatory on the
nights of UT 2018 February 7 and 21 and 2018 December 14 and 21.
We obtained precision Near Infra Red (NIR) Radial Velocities (RVs) of
K2-25 with the Habitable Zone Planet Finder (HPF) with the twofold
goal to constrain the mass of K2-25b and the obliquity of the host
star. The HPF is a high-resolution (R∼55000) NIR fiber-fed
spectrograph on the 10m Hobby-Eberly Telescope (HET) at McDonald
Observatory in Texas.
Objects:
-----------------------------------------------------
RA (2000) DE Designation(s) (Period)
-----------------------------------------------------
04 13 05.61 +15 14 52.0 K2-25b = K2-25b (P=1.878)
-----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fig2.dat 75 5168 K2 light curve and ground-based transits
tablec1.dat 88 32 Out-of-transit RVs from HPF
tablec2.dat 38 31 In-transit RVs from HPF
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/289 : UCAC2 Catalogue (Zacharias+ 2004)
I/298 : LSPM-North Catalog (Lepine+ 2005)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/AJ/128/463 : A preliminary 20pc census from the NLTT catalogue (Reid+,2004)
J/ApJ/703/L99 : Outlandish orbit of HAT-P-7b (Winn+, 2009)
J/ApJ/723/L223 : Radial velocities of HAT-P-11 (Winn+, 2010)
J/ApJ/757/18 : Radial velocities 16 hot Jupiter host stars (Albrecht+, 2012)
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
J/AJ/143/93 : Rotational velocities in early-M stars (Reiners+, 2012)
J/ApJ/807/45 : Potentially habit. planets orbiting M dwarfs (Dressing+, 2015)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/ApJ/801/3 : Rotation periods for Q3-Q14 KOIs (Mazeh+, 2015)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
J/AJ/152/204 : HARPS-N radial velocities of HD 179070 (Lopez-Morales+, 2016)
J/ApJ/825/19 : Mass-radius relation for planets with Rp<4 (Wolfgang+, 2016)
J/ApJ/834/17 : Mass & radius of planets, moons, low mass stars (Chen+, 2017)
J/AJ/154/226 : Photometry and radial velocities of K2-131 (Dai+, 2017)
J/AJ/153/142 : RVs of systems hosting sub-Saturns (Petigura+, 2017)
J/ApJ/836/77 : Library of high-S/N optical spectra of FGKM stars (Yee+, 2017)
J/AJ/155/203 : HARPS-N RVs & activity indicators Kepler-1655 (Haywood+, 2018)
J/AJ/158/75 : Mid-type M dwarfs planet occurrence (Hardegree-Ullman+, 2019)
J/ApJ/871/63 : How to constrain your M dwarf II. Nearby binaries (Mann+,2019)
J/AJ/159/63 : New AO obs. of exoplanets & brown dwarf comp. (Bowler+, 2020)
J/AJ/159/83 : Transit analysis for the K2-25 system (Kain+, 2020)
J/AJ/159/100 : Flux & RVs of the dwarf G9-40 with K2 & HPF (Stefansson+,2020)
Byte-by-byte Description of file: fig2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Inst Instrument identifier (1)
6- 23 F18.10 d BJD [2457061/2458516] Barycentric Julian Date
flux-weighted midpoint
25- 36 F12.10 --- Flux [0.96/1.03] Normalized photometric flux
38- 49 F12.10 --- e_Flux [0.0007/0.03] Error in FLux
51- 62 F12.10 --- Model [0.97/1.03] Best-fit Transit model (2)
64- 75 F12.10 --- GP [0.97/1.03] Gaussian-Process red noise component
of the best-fit model
--------------------------------------------------------------------------------
Note (1): Instruments as follows:
K2 = K2 spacecraft in Campaign 4.
HDI1 = Half Degree imager on the 0.9m WIYN Telescope at Kitt Peak Observatory
on the night of 2018-02-07UT in SDSS z' bandpass.
HDI2 = Half Degree imager on the 0.9m WIYN Telescope at Kitt Peak Observatory
on the night of 2018-02-21UT in SDSS z' bandpass.
HDI3 = Half Degree imager on the 0.9m WIYN Telescope at Kitt Peak Observatory
on the night of 2018-12-14UT in SDSS z' bandpass.
HDI4 = Half Degree imager on the 0.9m WIYN Telescope at Kitt Peak Observatory
on the night of 2018-12-21UT in SDSS z' bandpass. Observed without the
diffuser during sub-optimal observing conditions (Moon
illumination 97%).
APO1 = ARCTIC imager on the 3.5m Telescope at Apache Point Observatory
on the night of 2017-09-17UT in SDSS i' bandpass.
APO2 = ARCTIC imager on the 3.5m Telescope at Apache Point Observatory
on the night of 2019-01-04UT in SDSS i' bandpass.
APO3 = ARCTIC imager on the 3.5m Telescope at Apache Point Observatory
on the night of 2019-01-18UT in SDSS z' bandpass. Observed without
the diffuser.
APO4 = ARCTIC imager on the 3.5m Telescope at Apache Point Observatory
on the night of 2019-01-25UT in SDSS i' bandpass.
APO5 = ARCTIC imager on the 3.5m Telescope at Apache Point Observatory
on the night of 2019-02-01UT in SDSS i' bandpass.
Note (2): Including transit and Gaussian Process red-noise model.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian Date (1)
15- 20 F6.1 m/s RVel Radial velocity
22- 25 F4.1 m/s e_RVel Error in RVel
27- 32 F6.1 m2/s2 dLW Differential line width indicator
34- 38 F5.1 m2/s2 e_dLW Error in dLW
40- 46 F7.1 --- CRX Chromatic activity indicator (2)
48- 52 F5.1 --- e_CRX Error in CRX (2)
54- 58 F5.3 --- IRT1 Line number 1 CaII Infrared Triplet line
activity indicator
60- 64 F5.3 --- e_IRT1 Error in IRT1
66- 70 F5.3 --- IRT2 Line number 2 CaII Infrared Triplet line
activity indicator
72- 76 F5.3 --- e_IRT2 Error in IRT2
78- 82 F5.3 --- IRT3 Line number 3 CaII Infrared Triplet line
activity indicator
84- 88 F5.3 --- e_IRT3 Error in IRT3
--------------------------------------------------------------------------------
Note (1): Flux-weighted midpoint of HPF RV observations.
Note (2): In units of m/s/Np where Np gives the wavelength ratio in Nepers.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD Barycentric Julian Date (1)
16- 23 F8.3 m/s RVel Radial velocity
25- 31 F7.3 m/s e_RVel Error estimate in RVel
33- 36 F4.1 --- S/N Signal-to-noise ratio of observation
38- 38 I1 --- Transit Transit identifier (2)
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Note (1): Flux-weighted midpoint of HPF RV observations.
Note (2): Transits as follows:
1 = Transit Dec 21, 2018;
2 = Transit Dec 28, 2018;
3 = Transit Jan 04, 2019.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 20-Nov-2020