J/AJ/167/79 He-10830 triplet EW in young stars (Krolikowski+, 2024)
The Strength and Variability of the Helium 10830Å Triplet in Young Stars,
with Implications for Exosphere Detection.
Krolikowski D.M., Kraus A.L., Tofflemire B.M., Morley C.V., Mann A.W.,
Vanderburg A.
<Astron. J., 167, 79 (2024)>
=2024AJ....167...79K 2024AJ....167...79K
ADC_Keywords: Exoplanets; YSOs; Atomic physics; Spectra, infrared
Keywords: Stellar activity ; Atomic spectroscopy ; Exoplanet atmospheres ;
Stellar chromospheres
Abstract:
Young exoplanets trace planetary evolution, in particular the
atmospheric mass loss that is most dynamic in youth. However, the high
activity level of young stars can mask or mimic the spectroscopic
signals of atmospheric mass loss. This includes the activity-sensitive
He-10830Å triplet, which is an increasingly important exospheric
probe. To characterize the He-10830 triplet at young ages, we present
time-series NIR spectra for young transiting planet hosts taken with
the Habitable-zone Planet Finder. The He-10830 absorption strength is
similar across our sample, except at the fastest and slowest
rotations, indicating that young chromospheres are dense and populate
metastable helium via collisions. Photoionization and recombination by
coronal radiation only dominates metastable helium population at the
active and inactive extremes. Volatile stellar activity, such as
flares and changing surface features, drives variability in the
He-10830 triplet. Variability is largest at the youngest ages before
decreasing to ≲5-10mÅ (or 3%) at ages above 300Myr, with six of
eight stars in this age range agreeing with there being no intrinsic
variability. He-10830 triplet variability is smallest and
age-independent at the shortest timescales. Intrinsic stellar
variability should not preclude detection of young exospheres, except
at the youngest ages. We recommend out-of-transit comparison
observations taken directly surrounding transit and observation of
multiple transits to minimize activity's effect. Regardless, caution
is necessary when interpreting transit observations in the context of
stellar activity, as many scenarios can lead to enhanced stellar
variability even on timescales of an hour.
Description:
To study the behavior of the He-10830 triplet at young ages, we
measure the feature's equivalent width (EW) from the HPF spectral time
series for each star. For this analysis, we must first correct the
spectra for telluric contamination before measuring the EWs. We
describe our procedures for both of these steps in section 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 37 564 Helium 10830Angstrom triplet equivalent width
measurements
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See also:
J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)
J/MNRAS/422/2024 : X-ray-age relation & exoplanet evaporation (Jackson+, 2012)
J/ApJ/795/161 : Activity & rotation in Praesepe & Hyades (Douglas+, 2014)
J/ApJ/809/161 : X-ray obs. & membership probabilities of M37 (Nunez+, 2015)
J/A+A/581/A47 : Lines and continuum sky emission in the NIR (Oliva+, 2015)
J/ApJ/806/183 : Planet radii of Kepler Object of Interest (Wolfgang+, 2015)
J/ApJ/839/97 : HeI 5876 & 10830Å EWs solar-type stars (Andretta+, 2017)
J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)
J/A+A/612/A49 : 324 CARMENES M dwarfs velocities (Reiners+, 2018)
J/AJ/158/87 : 86 cool dwarfs observed K2 Campaigns 1-17 (Dressing+, 2019)
J/A+A/632/A24 : HeI IR triplet measurements for Mdwarfs (Fuhrmeister+, 2019)
J/A+A/640/A52 : M dwarfs HeI UR triplet variability (Fuhrmeister+, 2020)
J/ApJ/899/29 : Radial velocities of TOI-1728 with HPF (Kanodia+, 2020)
J/AJ/159/100 : Flux & RVs of dwarf G9-40 with K2 & HPF (Stefansson+, 2020)
J/AJ/162/82 : IRD & HPF spectra of TRAPPIST-1b,e &f (Krishnamurthy+, 2021)
J/AJ/162/110 : Gaia EDR3 census Taurus-Auriga complex (Krolikowski+, 2021)
J/AJ/161/65 : THYME. IV. 3 Exoplanets around TOI-451 B (Newton+, 2021)
J/AJ/161/171 : THYME V. Discovering stellar association (Tofflemire+, 2021)
J/AJ/163/247 : HIRES, PEPSI & TRES rvel of V1298 Tau (Johnson+, 2022)
J/AJ/164/81 : Radial velocity & photometric flux TOI-3757 (Kanodia+, 2022)
J/AJ/164/115 : TESS Hunt Young & Maturing Exoplanets. VII. (Newton+, 2022)
J/AJ/163/68 : Fiducial stellar spectrum of HD 63433 (Zhang+, 2022)
J/AJ/163/67 : 5-55000Å spectrum of TOI 560 (Zhang+, 2022)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Object Object name
10- 21 F12.4 d JD [2458425/2459306] Julian Date, observation
midpoint
23- 28 F6.2 10-13m EW [168/750]? Helium triplet equivalent width
30- 35 F6.2 10-13m e_EW [3/241]? Uncertainty in EW
37- 37 I1 --- f_EW [1/3]? Flag for EW (1)
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Note (1): Reason for missing EW measurement as follows:
1 = low spectrum signal-to-noise;
2 = failed spectral fit;
3 = bad spectral fit.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 04-Jun-2024