A Comet Active Beyond the Crystallization Zone

  title={A Comet Active Beyond the Crystallization Zone},
  author={David C. Jewitt and Man-To Hui and Max J. Mutchler and H. Weaver and Jing Li and Jessica Agarwal},
  journal={The Astrophysical Journal Letters},
We present observations showing inbound long-period comet C/2017 K2 (PANSTARRS) to be active at a record heliocentric distance. Nucleus temperatures are too low (60–70 K) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. Using the Hubble Space Telescope we find a sharply bounded, circularly symmetric dust coma 105 km in radius, with a total scattering cross-section of ∼105 km2. The coma has a logarithmic surface brightness… 

Figures and Tables from this paper

Distant Comet C/2017 K2 and the Cohesion Bottleneck

The distant long-period comet C/2017 K2 (PANSTARRS) has been outside the planetary region of the solar system for ∼3 Myr, negating the possibility that heat retained from the previous perihelion

Cometary Activity Begins at Kuiper Belt Distances: Evidence from C/2017 K2

We study the development of activity in the incoming long-period comet C/2017 K2 over the heliocentric distance range 9 ≲ r H ≲ 16 au. The comet continues to be characterized by a coma of

Probable Detection of Water Ice in the Coma of the Inbound Long-period Comet C/2017 K2 (PanSTARRS)

We present near-infrared reflectance spectra from 0.7 to 2.5 μm taken 2021 April 30 at the NASA Infrared Telescope Facility that show strong evidence for water ice within the coma of comet C/2017 K2

C/2010 U3 (Boattini): A Bizarre Comet Active at Record Heliocentric Distance

We present a photometric and dynamical study of comet C/2010 U3 (Boattini), which was seen active in prediscovery data as early as 2005 November at a new inbound record heliocentric distance of rH =

The Discus Comet: C/2014 B1 (Schwartz)

Long-period comet C/2014 B1 (Schwartz) exhibits a remarkable optical appearance, like that of a discus or bi-convex lens viewed edgewise. Our measurements in the four years since discovery reveal a

Pre-discovery Observations and Orbit of Comet C/2017 K2 (PANSTARRS)

We present a study of comet C/2017 K2 (PANSTARRS) using pre-discovery archival data taken from 2013 to 2017. Our measurements show that the comet has been marginally increasing in activity since at

A Look at Outbursts of Comet C/2014 UN271 (Bernardinelli–Bernstein) near 20 au

Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the

Discovery of Carbon Monoxide in Distant Comet C/2017 K2 (PANSTARRS)

Optical observations of the Oort cloud comet C/2017 K2 (PANSTARRS) show that its activity began at large heliocentric distances (up to 35 au), which cannot be explained by either the sublimation or

Activity of Comets Constrains the Chemistry and Structure of the Protoplanetary Disk

Recent data of molecular clouds and protoplanetary disks constrain the composition and structure of the disk and planetesimals. Laboratory experiments suggest that dust accretion in disks stops at

Characterization of the Nucleus, Morphology, and Activity of Interstellar Comet 2I/Borisov by Optical and Near-infrared GROWTH, Apache Point, IRTF, ZTF, and Keck Observations

We present visible and near-infrared (NIR) photometric and spectroscopic observations of interstellar object (ISO) 2I/Borisov taken from 2019 September 10 to 2019 December 20 using the GROWTH, the



Activity of comets at large heliocentric distances pre-perihelion


Centaurs are believed to be Kuiper Belt objects in transition between Jupiter and Neptune before possibly becoming Jupiter family comets. Some indirect observational evidence is consistent with the

Coma expansion and photometry of comet Bowell (1980b)

What drives the dust activity of comet 67P/Churyumov-Gerasimenko?

We use the gravitational instability formation scenario of cometesimals to derive the aggregate size that can be released by the gas pressure from the nucleus of comet 67P/Churyumov-Gerasimenko for


Remote investigations of ancient matter in the solar system have traditionally been carried out through observations of long-period (LP) comets, which are less affected by solar irradiation than

Comet Bowell /1980b/ - An active-looking dormant object

The absence of molecular emissions in the spectrum of Comet Bowell, a nearly constant amount of dust in its coma, a slow expansion rate of the coma and implied low particle velocities, a tail width


We report new observations of the prototype main-belt comet (active asteroid) 133P/Elst-Pizarro taken at high angular resolution using the Hubble Space Telescope. The object has three main

Gas release in comet nuclei.

The model of 0.2 g cm-3 density is found to reproduce quite well many of the light-curve and activity characteristics of comet P/Halley.

Surface brightness profiles of 10 comets

CCD photometric observations of the comae of 10 comets, obtained at the 4-m and 2.1-m telescopes at KPNO during 1985-1986 using filters centered at 700.5, 650.0, or 546.0 nm, are reported. The data

Acceleration of individual, decimetre-sized aggregates in the lower coma of comet 67P/Churyumov-Gerasimenko

We present OSIRIS/NAC observations of decimetre-sized, likely ice-containing aggregates ejected from a confined region on the surface of comet 67P/Churyumov-Gerasimenko. The images were obtained in