Formation of Charon’s Red Poles From Seasonally Cold-Trapped Volatiles. (arXiv:1903.03724v1 [astro-ph.EP])

Formation of Charon’s Red Poles From Seasonally Cold-Trapped Volatiles. (arXiv:1903.03724v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Grundy_W/0/1/0/all/0/1">W.M. Grundy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cruikshank_D/0/1/0/all/0/1">D.P. Cruikshank</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gladstone_G/0/1/0/all/0/1">G.R. Gladstone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Howett_C/0/1/0/all/0/1">C.J.A. Howett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lauer_T/0/1/0/all/0/1">T.R. Lauer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spencer_J/0/1/0/all/0/1">J.R. Spencer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Summers_M/0/1/0/all/0/1">M.E. Summers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buie_M/0/1/0/all/0/1">M.W. Buie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Earle_A/0/1/0/all/0/1">A.M. Earle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ennico_K/0/1/0/all/0/1">K. Ennico</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parker_J/0/1/0/all/0/1">J. Wm. Parker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Porter_S/0/1/0/all/0/1">S.B. Porter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Singer_K/0/1/0/all/0/1">K.N. Singer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stern_S/0/1/0/all/0/1">S.A. Stern</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Verbiscer_A/0/1/0/all/0/1">A.J. Verbiscer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beyer_R/0/1/0/all/0/1">R.A. Beyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Binzel_R/0/1/0/all/0/1">R.P. Binzel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Buratti_B/0/1/0/all/0/1">B.J. Buratti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cook_J/0/1/0/all/0/1">J.C. Cook</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ore_C/0/1/0/all/0/1">C.M. Dalle Ore</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Olkin_C/0/1/0/all/0/1">C.B. Olkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parker_A/0/1/0/all/0/1">A.H. Parker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Protopapa_S/0/1/0/all/0/1">S. Protopapa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Quirico_E/0/1/0/all/0/1">E. Quirico</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Retherford_K/0/1/0/all/0/1">K.D. Retherford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robbins_S/0/1/0/all/0/1">S.J. Robbins</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schmitt_B/0/1/0/all/0/1">B. Schmitt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stansberry_J/0/1/0/all/0/1">J.A. Stansberry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Umurhan_O/0/1/0/all/0/1">O.M. Umurhan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weaver_H/0/1/0/all/0/1">H.A. Weaver</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Young_L/0/1/0/all/0/1">L.A. Young</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zangari_A/0/1/0/all/0/1">A.M. Zangari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bray_V/0/1/0/all/0/1">V.J. Bray</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cheng_A/0/1/0/all/0/1">A.F. Cheng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McKinnon_W/0/1/0/all/0/1">W.B. McKinnon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McNutt_R/0/1/0/all/0/1">R.L. McNutt Jr.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moore_J/0/1/0/all/0/1">J.M. Moore</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nimmo_F/0/1/0/all/0/1">F. Nimmo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reuter_D/0/1/0/all/0/1">D.C. Reuter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schenk_P/0/1/0/all/0/1">P.M. Schenk</a>, the <a href="http://arxiv.org/find/astro-ph/1/au:+Team_New_Horizons_Science/0/1/0/all/0/1">New Horizons Science Team</a>

A unique feature of Pluto’s large satellite Charon is its dark red northern
polar cap. Similar colours on Pluto’s surface have been attributed to organic
macromolecules produced by energetic radiation processing of hydrocarbons. The
polar location of this material on Charon implicates the temperature extremes
that result from Charon’s high obliquity and long seasons. The escape of
Pluto’s atmosphere provides a potential feed stock for production of complex
chemistry. Gas from Pluto that is transiently cold-trapped and processed at
Charon’s winter pole was proposed as an explanation on the basis of an image of
Charon’s northern hemisphere, but not modelled quantitatively. Here we report
images of the southern hemisphere illuminated by Pluto-shine and also images
taken during the approach phase showing the northern polar cap over a range of
longitudes. We model the surface thermal environment on Charon, the supply and
temporary cold-trapping of material escaping from Pluto, and, while
cold-trapped, its photolytic processing into more complex and less volatile
molecules. The model results are consistent with the proposed mechanism
producing the observed colour pattern on Charon.

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