J/AJ/167/79ivo://CDS.VizieR/J/AJ/167/79doi:10.26093/cds/vizier.51670079CDSKrolikowski D.M.Kraus A.L.Tofflemire B.M.Morley C.V.Mann A.W.,Vanderburg A.2026-03-27T20:03:59Z2024-06-19T06:12:40ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frexoplanetsyoung-stellar-objectsatomic-physicsinfrared-astronomyspectroscopyYoung 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-10830{AA} 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^-10^m{AA} (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.2024AJ....167...79Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/167/79CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/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 & 10830{AA} 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 : 5-55000{AA} spectrum of TOI 560 (Zhang+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/167/79https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/167/79http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/167/79https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/167/79https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/167/79http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/167/79GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/AJ/167/79/table3Helium 10830Angstrom triplet equivalent width measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObjectObject namemeta.id;meta.maincharJD[2458425/2459306] Julian Date, observation midpointdtime.epochdoubleEW[168/750]? Helium triplet equivalent width1e-13mspect.line.eqWidthfloatnullablee_EW[3/241]? Uncertainty in EW1e-13mstat.error;spect.line.eqWidthfloatnullablef_EW[1/3]? Flag for EW (1)meta.codeintnullable