Friday, August 4, 2017

Comets & Asteroids - Summary for May 2017

During the month of May 2017, 2 new comets were discovered and cometary activity was detected for 1 previously discovered object (earlier designated as an asteroid).  "Current comet magnitudes" & "Daily updated asteroid flybys" pages are available at the top of this blog (or just click on the underline text here). See below for the "Other news" section.

The dates below refer to the date of issuance of CBET (Central Bureau Electronic  Telegram)  which reported the official news & designations.

- Comet Discoveries

May 24 Discovery of C/2017 K1 (PANSTARRS)
May 24 Discovery of C/2017 K2 (PANSTARRS)

- Cometary activity detected

May 28 Cometary activity detected in 2016 WM_48 = P/2016 WM_48 (LEMMON)

- Other news 

May 02 H. H. Hsieh reports on CBET 4388 that r'-band observations taken on Apr. 26 and 29 with the Gemini South Observatory (seven 100-s exposures per night; queue observer J. Chavez) show that comet 259P (cf. IAUC 8969; CBET 3115), which has been previously identified as an active minor planet and main-asteroid-belt comet candidate, is currently active. According to CBET 4388: "Including its previously observed active apparition in 2008 (IAUC 8969), these observations mark the second time that comet 259P has been seen to be active.  The fact that 259P exhibits regularly repeated periods of activity, interspersed with periods of quiescence, is a strong indicator that its activity is driven by the sublimation of volatile material, consistent with its initial identification as an ice-bearing main-asteroid-belt comet."

May 18 Hubble Spots Moon Around "2007 OR10", Third Largest Dwarf Planet in the Kuiper Belt. The team's results appeared in The Astrophysical Journal Letters: "2007 OR10 is currently the third largest known dwarf planet in the trans-Neptunian region, with an effective radiometric diameter of ∼1535 km. It has a slow rotation period of ∼45 hr that was suspected to be caused by tidal interactions with a satellite undetected at that time. Here, we report on the discovery of a likely moon of 2007 OR10, identified on archival Hubble Space Telescope WFC3/UVIS system images."

Credits: NASA, ESA, C. Kiss (Konkoly Observatory), and J. Stansberry (STScI)

May 24 CBET 4394 reports that minor planet (190166) 2005 UP156 is a fully-synchronous binary system with an orbital/rotational period of 40.542 +/- 0.008 hr.  The V magnitude was 16.0 on May 4, brightening to 15.2 on May 23.  The out-of-eclipse lightcurve shows an amplitude of about 0.5 magnitude with eclipse attenuations of about 0.6 mag.  The deeper event lasts about 2.8 hours.  The effective secondary-to-primary diameter ratio is estimated to be 0.8 +/- 0.1. 

May 26 A possible impact flash on #Jupiter was imaged by on May 26 by S. Pedranghelu with at least 2 independent confirmations. More info on see our blog post here

Credit: T. Riessler 

May 29 RIP Dr. Michael Francis A'Hearn (1940 - 2017). PI for the NASA Deep Impact; he introduced Afρ parameter for comets.

Credit: M. Mendelsohn

by Ernesto Guido