Possible outburst and disintegration of comet C/2022 R2 (ATLAS)
ATel #15658; Michael S. P. Kelley (University of Maryland), Quanzhi Ye (University of Maryland), on behalf of the Zwicky Transient Facility Collaboration
on 10 Oct 2022; 21:40 UT
Credential Certification: Kumar Venkataramani (kumarv@caltech.edu)
Comet C/2022 R2 (ATLAS) is a long-period comet with a perihelion distance of 0.63 au on 2022 Oct 25 ( Minor Planet Center 2022). Observations of the comet with the Zwicky Transient Facility (ZTF; Bellm et al. 2019, PASP, 131, a8002) measured in 5 arcsec radius apertures (PS1 photometric system) show that the
comet's absolute brightness increased approximately following a power-law function of heliocentric distance with an approximate slope of -7, based on the following apparent magnitudes: g=17.49+/-0.02,
r=16.11+/-0.01, and r=15.31+/-0.02 mag, on 2022 Sep 19.51, 25.51, and 29.51 UTC at rh=0.97, 0.90, and 0.83 au, respectively (we assumed g-r=0.55 mag). By the next observational epoch on Oct 03.53 (rh=0.78 au), the comet had brightened to r=14.24+/-0.02 mag, suggestive of either an outburst of strength ~-0.5 mag or a change in the brightening rate, steepening to ~rh**-12. The comet's brightness subsequently faded to r=14.47+/-0.03 and 14.77+/-0.02 mag, on Oct 06.53 and 09.53, at rh=0.75 and 0.72 au, respectively. Overall, the comet's absolute brightness was fainter by +0.9 mag with respect to the original brightening rate of rh**-7 extrapolated to the Oct 9 observations. The coma morphology evolved from one dominated by a tail (Sep 19) to a tail with a strong nearly circular coma (Oct 3), and trending back to a tail dominated morphology (Oct 9). The light-curve variability and morphological changes suggest a dramatic development occurring at the comet, possibly fragmentation or disintegration.
Based on observations obtained with the Samuel Oschin Telescope 48-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science
Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, Weizmann Institute for Science, Oskar Klein Center at Stockholm University, University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, TANGO Consortium of Taiwan, University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW.
