Thursday, May 31, 2018

Comets & Asteroids - Summary for April & May 2018

During the 2-month period April through May 2018, 2 new comets were discovered, cometary activity was detected for 2 previously discovered objects (earlier designated as asteroids) and there  was 1 comet recovery. "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

Apr 26  Discovery of P/2018 H2 (PANSTARRS)
May 31 Discovery of C/2018 K1 (Weiland)

- Cometary activity detected

Apr 17 Cometary activity detected in A/2018 F4 = C/2018 F4 (PANSTARRS) *
Apr 20 Cometary activity detected in 2018 EF9 = C/2018 EF9 (Lemmon)

* This object initially received the unusual designation A/2018 F4 by G. V. Williams on MPEC 2018-F139 because of the hyperbolic orbit.

See also MPEC 2018-H21: "This object, originally announced as A/2018 F4, is being redesignated as a comet.  K. Sarneczky, Konkoly Observatory, reports that five stacked 120-s unfiltered CCD images taken on Apr. 9.9 UT with the 0.60-m Schmidt telescope at Piszkesteto, Hungary, show a broad fan-shaped coma of diameter nearly 6", elongated toward the east.  R. Weryk (University of Hawaii) reports that images taken with the 3.6-m CFHT on Mauna Kea on Apr. 13.39 UT show that the object has a FWHM of 2".4 (larger than the 1".4 FWHM for nearby stars) and a broad, short tail towards the east".

- Comet Recoveries

Apr 18  Recovery of P/2011 CR42 (CATALINA) as P/2018 H1

- Other news

Apr 16 New paper on Arxiv by Jewitt et al.: "The Nucleus of Active Asteroid 311P/(2013 P5) PANSTARRS".

Credits: Jewitt et al.

Apr 23 New paper on Arxiv by Nesvorny et al.: "Bi-lobed Shape of Comet 67P from a Collapsed Binary".

Apr 24 Dust, stars, and cosmic rays swirling around Comet 67P, captured by the @ESA_Rosetta probe (processing by @landru79)

Credit: Esa Rosetta

Apr 25 Gaia Data Release 2: Observations of solar system objects. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Gaia Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs.  The published Gaia data set in data release 2 only contains a selected sample of asteroids, as the observations of many more have already been collected, and will become available in future releases. By the end of the mission there will most probably be more than 300.000, and the accurate positions, 100s times better than in the past, will disclosing new possibility of investigation. The pictures below show a colorful plot of the orbits of the asteroids in Gaia’s second data release (coloured according to perihelion distance), between the Sun and Jupiter. As usual in scaled plots, the Solar System appears crowded and individual lines merge in the region of the Main Belt, between Mars and Jupiter, where most asteroids concentrate. In reality, of course, these asteroid trajectories are millions of km apart.

Credit: Credit: ESA/Gaia/DPAC, P. Tanga

May 07 Silicon Valley Astronomy Lecture: Rubble Piles in the Sky | @michael_w_busch reviews the near-Earth population, programs to track and characterize near-Earth asteroids, and current efforts to address the danger of asteroid impacts. Watch it here on Youtube

May 09 ESO Press Release: Exiled Asteroid Discovered in Outer Reaches of Solar System - ESO telescopes find first confirmed carbon-rich asteroid in Kuiper Belt: "An international team of astronomers has used ESO telescopes to investigate a relic of the primordial Solar System. The team found that the unusual Kuiper Belt Object 2004 EW95 is a carbon-rich asteroid, the first of its kind to be confirmed in the cold outer reaches of the Solar System. This curious object likely formed in the asteroid belt between Mars and Jupiter and has been flung billions of kilometres from its origin to its current home in the Kuiper Belt."

May 11 OSSOS Survey, the complete data release is now published!  Eight hundred and forty precisely defined orbits, with a survey simulator calibrating their detection efficiency. Article by Michele Bannister for @ConversationUK: "How @OSSOSurvey discovered 840 minor planets beyond Neptune – and what they can tell us"

Credit: OSSOS Survey

May 15 New paper on Arxiv by Fern├índez et al.: "Dynamical evolution and end states of active and inactive Centaurs". 

Credit: Fernández et al.

May 21 New paper on Nature Astronomy by Shi et al..: "Coma morphology of comet 67P controlled by insolation over irregular nucleus". Shi et al. study the activity of comet #67P using #Rosetta images, finding that diffuse activity is controlled by sunlight and it can be focused by the roughness of the nucleus' surface to create the nice coma shapes.

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; Nature Astronomy

Credit: Hsieh et al.

May 28 New paper on Arxiv by J. Agarwal & M. Mommert: "Nucleus of active asteroid 358P/Pan-STARRS (P/2012 T1)". 

by Ernesto Guido