Contemporaneous Multi-Wavelength and Precovery Observations of Active Centaur P/2019 LD2 (ATLAS. (arXiv:2011.09993v1 [astro-ph.EP])

Contemporaneous Multi-Wavelength and Precovery Observations of Active Centaur P/2019 LD2 (ATLAS. (arXiv:2011.09993v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kareta_T/0/1/0/all/0/1">Theodore Kareta</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Woodney_L/0/1/0/all/0/1">Laura M. Woodney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schambeau_C/0/1/0/all/0/1">Charles Schambeau</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fernandez_Y/0/1/0/all/0/1">Yanga Fernandez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pinto_O/0/1/0/all/0/1">Olga Harrington Pinto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wierzchos_K/0/1/0/all/0/1">Kacper Wierzchos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Womack_M/0/1/0/all/0/1">M. Womack</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bus_S/0/1/0/all/0/1">S.J. Bus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Steckloff_J/0/1/0/all/0/1">Jordan Steckloff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sarid_G/0/1/0/all/0/1">Gal Sarid</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Volk_K/0/1/0/all/0/1">Kathryn Volk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harris_W/0/1/0/all/0/1">Walter M. Harris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reddy_V/0/1/0/all/0/1">Vishnu Reddy</a>

The discovery of Gateway Centaur P/2019 LD2 (ATLAS) (Sarid et al., 2019)
provides the first opportunity to observe the orbital migration of a Solar
System small body from a Centaur orbit to a Jupiter Family Comet (JFC) some
four decades from now (Kareta et al., 2020, Hsieh et al., 2020.) The Gateway
transition region is beyond where water ice can power cometary activity, so
coma production there is as poorly understood as in all Centaurs. We present
contemporaneous multi-wavelength observations of LD2 from 2020 July 2-4: Gemini
North visible imaging, NASA IRTF near-infrared spectroscopy, and ARO
Sub-Millimeter Telescope millimeter-wavelength spectroscopy. Precovery DECam
images limit the nucleus’s effective radius to $sim$ 1.2 km or less and
Catalina Sky Survey archival data show only smooth changes in brightness. The
observed colors of LD2’s coma are $g’ – r’ = 0.70 pm 0.07$ and $r’ – i’ = 0.26
pm 0.07$ with a dust production rate of $sim 10-20$ kg/s. We used LD2’s coma
morphology to estimate the dust coma’s outflow velocity between $ v sim
0.6-3.3$ m/s. We do not detect CO towards LD2, giving a 2020 Jul 2-3 production
rate upper limit of $Q(CO) < $ 3.8 x 10$^{27}$ mol s$^{-1}$ (3-$sigma$). The
near-infrared spectra show evidence for water ice at the 1-10% level depending
on grain size. Spatial profiles and archival data support the idea of ongoing
consistent activity. The evidence supports the hypothesis that LD2 is a typical
small Centaur that will become a typical JFC, and thus LD2 is critical to
understanding the transition between these two populations. Finally, we discuss
strategies for taking advantage of the windfall of cometary science from a
community-wide, long baseline monitoring effort of P/2019 LD2.

The discovery of Gateway Centaur P/2019 LD2 (ATLAS) (Sarid et al., 2019)
provides the first opportunity to observe the orbital migration of a Solar
System small body from a Centaur orbit to a Jupiter Family Comet (JFC) some
four decades from now (Kareta et al., 2020, Hsieh et al., 2020.) The Gateway
transition region is beyond where water ice can power cometary activity, so
coma production there is as poorly understood as in all Centaurs. We present
contemporaneous multi-wavelength observations of LD2 from 2020 July 2-4: Gemini
North visible imaging, NASA IRTF near-infrared spectroscopy, and ARO
Sub-Millimeter Telescope millimeter-wavelength spectroscopy. Precovery DECam
images limit the nucleus’s effective radius to $sim$ 1.2 km or less and
Catalina Sky Survey archival data show only smooth changes in brightness. The
observed colors of LD2’s coma are $g’ – r’ = 0.70 pm 0.07$ and $r’ – i’ = 0.26
pm 0.07$ with a dust production rate of $sim 10-20$ kg/s. We used LD2’s coma
morphology to estimate the dust coma’s outflow velocity between $ v sim
0.6-3.3$ m/s. We do not detect CO towards LD2, giving a 2020 Jul 2-3 production
rate upper limit of $Q(CO) < $ 3.8 x 10$^{27}$ mol s$^{-1}$ (3-$sigma$). The
near-infrared spectra show evidence for water ice at the 1-10% level depending
on grain size. Spatial profiles and archival data support the idea of ongoing
consistent activity. The evidence supports the hypothesis that LD2 is a typical
small Centaur that will become a typical JFC, and thus LD2 is critical to
understanding the transition between these two populations. Finally, we discuss
strategies for taking advantage of the windfall of cometary science from a
community-wide, long baseline monitoring effort of P/2019 LD2.

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