Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk. (arXiv:1807.10766v2 [astro-ph.EP] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Wagner_K/0/1/0/all/0/1">Kevin Wagner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Follette_K/0/1/0/all/0/1">Katherine B. Follette</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Close_L/0/1/0/all/0/1">Laird M. Close</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Apai_D/0/1/0/all/0/1">Dániel Apai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gibbs_A/0/1/0/all/0/1">Aidan Gibbs</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keppler_M/0/1/0/all/0/1">Miriam Keppler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muller_A/0/1/0/all/0/1">André Müller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Henning_T/0/1/0/all/0/1">Thomas Henning</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kasper_M/0/1/0/all/0/1">Markus Kasper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wu_Y/0/1/0/all/0/1">Ya-Lin Wu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Long_J/0/1/0/all/0/1">Joseph Long</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Males_J/0/1/0/all/0/1">Jared Males</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morzinski_K/0/1/0/all/0/1">Katie Morzinski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McClure_M/0/1/0/all/0/1">Melissa McClure</a>
PDS 70b is a recently discovered and directly imaged exoplanet within the
wide ($gtrsim$40 au) cavity around PDS 70 (Keppler et al. 2018, M”uller et
al. 2018). Ongoing accretion onto the central star suggests that accretion onto
PDS 70b may also be ongoing. We present the first high contrast images at
H$alpha$ (656 nm) and nearby continuum (643 nm) of PDS 70 utilizing the MagAO
system. The combination of these filters allows for the accretion rate of the
young planet to be inferred, as hot infalling hydrogen gas will emit strongly
at H$alpha$ over the optical continuum. We detected a source in H$alpha$ at
the position of PDS 70b on two sequential nights in May 2018, for which we
establish a false positive probability of $<$0.1%. We conclude that PDS 70b is
a young, actively accreting planet. We utilize the H$alpha$ line luminosity to
derive a mass accretion rate of $dot M= 10^{-8pm1}$ M$_{Jup}/yr$, where the
large uncertainty is primarily due to the unknown amount of optical extinction
from the circumstellar and circumplanetary disks. PDS 70b represents the second
case of an accreting planet interior to a disk gap, and is among the early
examples of a planet observed during its formation.
PDS 70b is a recently discovered and directly imaged exoplanet within the
wide ($gtrsim$40 au) cavity around PDS 70 (Keppler et al. 2018, M”uller et
al. 2018). Ongoing accretion onto the central star suggests that accretion onto
PDS 70b may also be ongoing. We present the first high contrast images at
H$alpha$ (656 nm) and nearby continuum (643 nm) of PDS 70 utilizing the MagAO
system. The combination of these filters allows for the accretion rate of the
young planet to be inferred, as hot infalling hydrogen gas will emit strongly
at H$alpha$ over the optical continuum. We detected a source in H$alpha$ at
the position of PDS 70b on two sequential nights in May 2018, for which we
establish a false positive probability of $<$0.1%. We conclude that PDS 70b is
a young, actively accreting planet. We utilize the H$alpha$ line luminosity to
derive a mass accretion rate of $dot M= 10^{-8pm1}$ M$_{Jup}/yr$, where the
large uncertainty is primarily due to the unknown amount of optical extinction
from the circumstellar and circumplanetary disks. PDS 70b represents the second
case of an accreting planet interior to a disk gap, and is among the early
examples of a planet observed during its formation.
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