Detection of He I 10830 AA~ absorption during the transit of a warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder. (arXiv:1910.02070v1 [astro-ph.EP])

Detection of He I 10830 AA~ absorption during the transit of a warm Neptune around the M-dwarf GJ 3470 with the Habitable-zone Planet Finder. (arXiv:1910.02070v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ninan_J/0/1/0/all/0/1">Joe P. Ninan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stefansson_G/0/1/0/all/0/1">Gudmundur Stefansson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mahadevan_S/0/1/0/all/0/1">Suvrath Mahadevan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bender_C/0/1/0/all/0/1">Chad Bender</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robertson_P/0/1/0/all/0/1">Paul Robertson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ramsey_L/0/1/0/all/0/1">Lawrence Ramsey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Terrien_R/0/1/0/all/0/1">Ryan Terrien</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wright_J/0/1/0/all/0/1">Jason Wright</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Diddams_S/0/1/0/all/0/1">Scott A. Diddams</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kanodia_S/0/1/0/all/0/1">Shubham Kanodia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cochran_W/0/1/0/all/0/1">William Cochran</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Endl_M/0/1/0/all/0/1">Michael Endl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ford_E/0/1/0/all/0/1">Eric B. Ford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fredrick_C/0/1/0/all/0/1">Connor Fredrick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Halverson_S/0/1/0/all/0/1">Samuel Halverson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hearty_F/0/1/0/all/0/1">Fred Hearty</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jennings_J/0/1/0/all/0/1">Jeff Jennings</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaplan_K/0/1/0/all/0/1">Kyle Kaplan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lubar_E/0/1/0/all/0/1">Emily Lubar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Metcalf_A/0/1/0/all/0/1">Andrew J. Metcalf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Monson_A/0/1/0/all/0/1">Andrew Monson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nitroy_C/0/1/0/all/0/1">Colin Nitroy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roy_A/0/1/0/all/0/1">Arpita Roy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schwab_C/0/1/0/all/0/1">Christian Schwab</a>

Understanding the dynamics and kinematics of out-flowing atmospheres of hot
and warm exoplanets is crucial to understanding the origins and evolutionary
history of the exoplanets near the evaporation desert. Recently, ground based
measurements of the meta-stable Helium atom’s resonant absorption at 10830
AA~has become a powerful probe of the base environment which is driving the
outflow of exoplanet atmospheres. We report the detection of He I 10830 AA~in
absorption (equivalent width $sim$ $0.012 pm 0.002$ AA) in the exosphere of
a warm Neptune orbiting the M-dwarf, GJ 3470, during three transits using the
Habitable Zone Planet Finder (HPF) near infrared spectrograph. This marks the
first reported detection of He I 10830 AA, atmospheric absorption for a
planet orbiting a M-dwarf. Our detected absorption is broad and its blueshifted
wing extends to -36 km/sec, the largest reported in the literature to date. We
modelled the state of Helium atoms in the exosphere of GJ3470b based on
assumptions on the UV and X-ray flux of GJ 3470, and found our measurement of
flux-weighted column density of meta-stable state He $= 2.4 times 10^{10}
mathrm{cm^{-2}}$, derived from our transit observations, to be consistent with
model, within its uncertainties. The methodology developed here will be useful
to study and constrain the atmosphere outflow models of other exo-planets, like
GJ 3470b, which are near the edge of the evaporation desert.

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