Lyman alpha and energetic particles H escape Allison

Lyman alpha and energetic particles: H escape Allison Youngblood NASA GSFC / USRA

H escape: responsible for sculpting observed 1. 7 Rsun radius gap Hot sub. Neptune desert Gas-rich Theory predictions from Lopez & Rice (2016): Atmospheric loss Gas-poor low completeness Owen & Wu 2013, 2017 Figure from Fulton et al. Formed gas-poor

Super-Earths Sub-Neptunes Teff = 4700– 6500 K Gap not ruled in or out yet for M dwarfs See also Ginzburg et al. 2018 for planet corepowered atmospheric loss. Fulton et al. 2018

Lyman alpha transit of escaping H atmosphere + stellar wind drag Bourrier et al. 2016 Laura Harbach

Bourrier et al. 2016

Thorny issues with precisely measuring Lyman alpha: ISM, geocorona, intrinsic profile shape Jeff Linsky / JILA

Reconstructing the intrinsic Lyα profiles Intrinsic Lyα profile Youngblood et al. 2016 2/23/18 Allison Youngblood 8

Reconstructing the intrinsic Lyα profiles Intrinsic Lyα profile Youngblood et al. 2016 2/23/18 Allison Youngblood 9

Reconstructing the intrinsic Lyα profiles + N(HI) = 1018 cm-2, b = 12 km/s, D/H = 1. 5 × 10 -5 Observed Lyα profile Youngblood et al. 2016 2/23/18 DI absorption Allison Youngblood HI absorption 10

Reconstructing the intrinsic Lyα profiles Reconstructed F(Lyα) = (3. 9 ± 0. 4) × 10 -13 erg cm-2 s-1 Youngblood et al. 2016 2/23/18 Allison Youngblood 11

Reconstructing the intrinsic Lyα profiles high spectral resolution is not feasible for current exoplanet transits of interest Jeff Linsky / JILA 2/23/18 Allison Youngblood 12

Unknown intrinsic profile shapes Solar The Sun’s Lyα profile Network (high B; low opacity) Internetwork (low B; high opacity) Solar Lyα selfreversal depends on magnetic field strength and orientation Tian+ 2009 (SOHO/SUMER) See also Curdt+ 2001, Fontenla+ 1988 2/23/18 Allison Youngblood 13

But did we pick the right intrinsic Lyα profile? Kapteyn’s Star, Mg II Youngblood et al. 2016 2/23/18 Allison Youngblood 14

Directly determine intrinsic Lyα profile from high-RV stars • HST Cycle 25 – PI: Youngblood • Selected the nearest stars with high radial velocity • 3 M dwarfs, 1 K dwarf, 1 G dwarf • Elucidate a dependency of self-reversal on spectral type • Reveal information about stellar magnetic fields • Improve accuracy of Lyα reconstructions 2/23/18 Allison Youngblood 15

Directly determine intrinsic Lyα profile from high-RV stars • Lines like Mg II (2796, 2802 Å) and Ca II (3933, 3968 Å) may also be similar to Lyα • And they are not as affected by the ISM Ca II The Sun: 2/23/18 Allison Youngblood 16

Lyman alpha reconstructions at R~1000 Si III Pineda et al. in prep FUMES Survey G 140 M R~10, 000 E 140 M R~50, 000 E 140 H R~100, 000 Add in as many prior constraints on parameters as possible! (e. g. , Bourrier et al. 2017) • Radial Velocities from other emission lines • Temperature of ISM H I atoms • ISM column density

Extended wings of Lyman alpha • < 5% of the total Lyman alpha flux • But potentially a significant “continuum” source (e. g. , important for photochemistry) Below the sensitivity of STIS E 140 H, E 140 M, and G 140 M spectra. Detectable with STIS G 140 L (out to ± 5000 km/s) and COS G 130 M (out to ± 1000 km/s) Extends out Youngblood et al. 2016 Pineda et al. in prep

Energetic