J/AJ/160/114 Radial velocity monitoring of TOI-421 (Carleo+, 2020)
The multiplanet system TOI-421: a warm Neptune and a super puffy mini-Neptune
transiting a G9 V star in a visual binary.
Carleo I., Gandolfi D., Barragan O., Livingston J.H., Persson C.M.,
Lam K.W.F., Vidotto A., Lund M.B., D'Angelo C.V., Collins K.A., Fossati L.,
Howard A.W., Kubyshkina D., Brahm R., Oklopcic A., Molliere P., Redfield S.,
Serrano L.M., Dai F., Fridlund M., Borsa F., Korth J., Esposito M.,
Diaz M.R., Nielsen L.D., Hellier C., Mathur S., Deeg H.J., Hatzes A.P.,
Benatti S., Rodler F., Alarcon J., Spina L., Santos A.R.G., Georgieva I.,
Garcia R.A., Gonzalez-Cuesta L., Ricker G.R., Vanderspek R., Latham D.W.,
Seager S., Winn J.N., Jenkins J.M., Albrecht S., Batalha N.M., Beard C.,
Boyd P.T., Bouchy F., Burt J.A., Butler R.P., Cabrera J., Chontos A.,
Ciardi D.R., Cochran W.D., Collins K.I., Crane J.D., Crossfield I.,
Csizmadia S., Dragomir D., Dressing C., Eigmuller P., Endl M., Erikson A.,
Espinoza N., Fausnaugh M., Feng F., Flowers E., Fulton B., Gonzales E.J.,
Grieves N., Grziwa S., Guenther E.W., Guerrero N.M., Henning T., Hidalgo D.,
Hirano T., Hjorth M., Huber D., Isaacson H., Jones M., Jordan A., Kabath P.,
Kane S.R., Knudstrup E., Lubin J., Luque R., Mireles I., Narita N.,
Nespral D., Niraula P., Nowak G., Palle E., Patzold M., Petigura E.A.,
Prieto-Arranz J., Rauer H., Robertson P., Rose M.E., Roy A., Sarkis P.,
Schlieder J.E., Segransan D., Shectman S., Skarka M., Smith A.M.S.,
Smith J.C., Stassun K., Teske J., Twicken J.D., Van Eylen V., Wang S.,
Weiss L.M., Wyttenbach A.
<Astron. J., 160, 114 (2020)>
=2020AJ....160..114C 2020AJ....160..114C
ADC_Keywords: Exoplanets; Stars, dwarfs; Spectra, optical; Spectra, infrared;
Radial velocities
Keywords: Exoplanet astronomy ; Exoplanet systems ; Exoplanets ; Mini Neptunes ;
Hot Neptunes ; Fundamental parameters of stars ;
High resolution spectroscopy ; Transit photometry ; Radial velocity
Abstract:
We report the discovery of a warm Neptune and a hot sub-Neptune
transiting TOI-421 (BD-141137, TIC94986319), a bright (V=9.9) G9 dwarf
star in a visual binary system observed by the Transiting Exoplanet
Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed
ground-based follow-up observations-comprised of Las Cumbres
Observatory Global Telescope transit photometry, NIRC2 adaptive optics
imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy
Radial velocity Planet Searcher, High Resolution Echelle Spectrometer,
and Planet Finder Spectrograph high-precision Doppler measurements-and
confirmed the planetary nature of the 16 day transiting candidate
announced by the TESS team. We discovered an additional radial
velocity signal with a period of five days induced by the presence of
a second planet in the system, which we also found to transit its host
star. We found that the inner mini-Neptune, TOI-421b, has an orbital
period of Pb=5.19672±0.00049days, a mass of
Mb=7.17±0.66M⊕, and a radius of
Rb=2.68-0.18+0.19R⊕, whereas the outer warm Neptune,
TOI-421c, has a period of Pc=16.06819±0.00035days, a mass of
Mc=16.42-1.04+1.06M⊕, a radius of
Rc=5.09-0.15+0.16R⊕, and a density of
ρc=0.685-0.072+0.080g/cm3. With its characteristics, the
outer planet (ρc=0.685-0.072+0.080g/cm3) is placed in the
intriguing class of the super-puffy mini-Neptunes. TOI-421b and
TOI-421c are found to be well-suited for atmospheric characterization.
Our atmospheric simulations predict significant Lyα transit
absorption, due to strong hydrogen escape in both planets, as well as
the presence of detectable CH4 in the atmosphere of TOI-421c if
equilibrium chemistry is assumed.
Description:
We started the RV follow-up of TOI-421 in 2019 February using the
FIbre-fed Echelle Spectrograph (FIES) mounted at the 2.56m Nordic
Optical Telescope (NOT) of Roque de los Muchachos Observatory (La
Palma, Spain). We employed the intermediate-resolution fiber, which
provides a resolving power of R=45000 over the wavelength range
3660-9275Å, and acquired 10 spectra between 2019 February 2 and
March 13.
We acquired 105 high-resolution (R=115000) spectra of TOI-421 using
the HARPS spectrograph mounted at the ESO-3.6m telescope of La Silla
Observatory, Chile. Our HARPS observations were performed over two
observing seasons between 2019 February and 2020 January.
Between 2019 September 17 and 2020 March 3, we obtained 28 spectra
(R=55000) of TOI-421 over 27 nights using the High Resolution Echelle
Spectrometer (HIRES) on the 10m Keck I telescope. The spectra were
collected using an iodine cell for wavelength reference. The median
exposure time was 680 s, which allowed us to achieve a S/N ratio of
200 per reduced pixel at 5500Å.
We monitored TOI-421 with the Planet Finder Spectrograph (PFS) mounted
on the 6.5m Magellan II Clay Telescope at Las Campanas Observatory
(LCO) in Chile. The observations were performed on nine different
nights, between 2019 February 18 and October 11. For these
observations, we used the 0.3"x2.5" slit, which delivers
high-resolution spectra with a resolving power of R=130000.
Objects:
---------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
---------------------------------------------------------------
05 27 24.83 -14 16 37.0 TOI-421 = TIC 94986319 (P=5.19672d)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 63 9 FIES RV measurements of TOI-421
table3.dat 63 105 HARPS RV measurements of TOI-421
table4.dat 63 33 HIRES RV measurements of TOI-421
table5.dat 63 9 PFS RV measurements of TOI-421
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/397/147 : Activity-rotation relation. in stars (Pizzolato+,2003)
J/A+A/468/1115 : Thorium and argon lines in the visible (Lovis+, 2007)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)
J/ApJ/720/1118 : i-band photometry of HAT-P-16 (Buchhave+, 2010)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/ApJS/197/8 : Kepler's candid. multiple planets (Lissauer+, 2011)
J/ApJ/743/48 : Stars with rot. per. & X-ray luminosities (Wright+, 2011)
J/ApJS/208/9 : Intrinsic colors & temper. of PMS stars (Pecaut+,2013)
J/A+A/564/A125 : AGN Torus model comparison of AGN CDFS (Buchner+, 2014)
J/A+A/572/A34 : Pulsating solar-like stars in Kepler (Garcia+, 2014)
J/ApJ/784/45 : Kepler's multiple planet candidates. III. (Rowe+, 2014)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (Sullivan+, 2015)
J/A+A/605/A111 : Surface rotation of Kepler red giant stars (Ceillier+, 2017)
J/MNRAS/466/1868 : Neptune-like planets overabundance (Cubillos+, 2017)
J/AJ/154/226 : Photometry and radial velocities of K2-131 (Dai+, 2017)
J/AJ/153/71 : Kepler follow-up obs. program. I. Imaging (Furlan+, 2017)
J/AJ/154/123 : RV follow-up of the HD3167 system (Gandolfi+, 2017)
J/ApJ/836/77 : Library of high-S/N optical spectra FGKM stars (Yee+, 2017)
J/ApJS/239/2 : Simulated exoplanets TESS list of targets (Barclay+, 2018)
J/A+A/612/A95 : K2-141 b radial velocity and light curve (Barragan+, 2018)
J/A+A/619/L10 : pi Men radial velocity curves (Gandolfi+, 2018)
J/AJ/156/102 : TESS Input Catalog & Candidate Target List (Stassun+, 2018)
J/AJ/158/45 : TESS light curve & RVs for HD 1397 (Brahm+, 2019)
J/ApJ/876/L24 : HARPS radial velocities host star HD15337 (Gandolfi+, 2019)
J/ApJ/874/107 : HARPS-N solar radial velocities & activity (Milbourne+,2019)
J/A+A/628/A64 : EPIC 212036875b griz light curves (Persson+, 2019)
J/AJ/158/177 : Near-resonance in system sub-Neptunes TESS (Quinn+, 2019)
J/ApJS/244/21 : Surface rotation & activity Kepler stars I. (Santos+, 2019)
J/ApJS/241/12 : Asteroseismic Target List (ATL) for TESS (Schofield+, 2019)
J/A+A/638/A5 : HD 285507 & AD Leo light and velocity curves (Carleo+,2020)
J/A+A/634/L4 : HST/STIS FUV spectra of K2-18 (dos Santos+, 2020)
J/AJ/159/145 : RVs and opt. photom. of the host star TOI-677 (Jordan+,2020)
J/AJ/159/57 : HST spectro. LCs of Kepler 51b & 51d (Libby-Roberts+, 2020)
Byte-by-byte Description of file: table[2345].dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d BJD Barycentric Julian Date; BJD-2450000 (1)
13- 19 F7.4 km/s RVel Radial velocity
21- 26 F6.4 km/s e_RVel Error on RVel (σRV)
28- 34 F7.4 km/s BIS ? Bisector span
36- 41 F6.4 km/s FWHM ? Full width at half maximum
43- 48 F6.3 [-] logRHK ? CaII H and K lines activity indicator
50- 54 F5.3 [-] e_logRHK ? Error on logRHK
56- 59 I4 s Texp Exposurer time
61- 63 I3 /pix S/N Signal to noise ratio at 550nm
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Note (1): Barycentric Julian dates are given in barycentric dynamical time
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 15-Dec-2020