Cometary Science Newsletter

Observations of Planetary Objects with Non-Planetary Spacecraft (Session B0.3)

COSPAR 2018 - Pasadena, California, 14-22 July 2018
Abstracts due February 9th

Missions not primarily designed for planetary observations are nevertheless valuable sources of observational data on major, dwarf, and minor planets, as well as comets. Example missions are the NASA/ESA SOHO and NASA STEREO solar and heliospheric missions, that have returned observations of numerous comets, the NASA Kepler exoplanet mission which has observed planets and various small bodies, and ESA's Gaia mapping mission. In this session, we address such observations carried out by past and current missions as well as projects that are in development and proposed. Contributions are invited to provide an overview of results from such observations, and those planned for the future. Contributions that provide insights into the securing of serendipitous planetary observations to help advise future efforts are particularly encouraged.

Abstracts for contributed presentations at Session B0.3 are due on February 9, 2018, and must be submitted on the COSPAR website—full details for abstract submission, as well as the detailed description of the content of the session are available at https://www.cospar-assembly.org.

Organizers - Geraint Jones (MSSL, University College London, UK) & Matthew Knight (University of Maryland, USA)

Rosetta Workshop and SWT - Registration and abstract submission OPEN!

Dear Colleagues,

Please note that abstract submission and registration is now open for the Rosetta science extravaganza in Rhodes in May/June. Please go to the web page to register and if you like, submit an abstract.

https://www.cosmos.esa.int/web/rosetta-swt-49

Note that the special rate available at the conference hotel is only available up to March 26th. Please use the form available in the accommodation section of the conference web page to secure your room!

Registration fee is expected to be around 300 Euros and will include the conference dinner and excursion and for those staying in the conference hotel, this will also include lunch. Exact costs will be made clearer nearer the time, once we have a better idea at the number of participants.

Please pass this message on, the meeting is open to all scientists interested in comets, solar system formation and evolution, etc.

Best regards,

Matt Taylor, on behalf of the SOC

Call for Observations of C/2016 R2 (PanSTARRS)

Recent observations at multiple wavelengths have revealed an atypical coma composition for comet C/2016 R2 (PanSTARRS), including very large CO production rates (Wierzchos and Womack, CBET4464) and the presence of N2+ and CO+ in the optical spectrum (Cochran and McKay, in press). We are working to obtain as many observations as possible at all wavelengths to fully characterize this comet, with observations already scheduled/obtained on facilities such as Spitzer, IRAM, SMT, and NASA IRTF. We encourage the cometary science community to observe this comet with any complementary or independent methods at their disposal. Of particular interest are data that can be obtained near simultaneously with scheduled observations with Spitzer on UT Feb 12 and Feb 21, though any observations obtained to date and over the next couple months will be beneficial. Please contact Adam McKay (adam.mckay@nasa.gov) with any questions or to express interest.

JWST Cycle 1 Update: 88P/Howell and 313P/Gibbs

The James Webb Space Telescope's Guaranteed-Time Observation (GTO) program includes observations of comets in Heidi Hammel's "Solar System Observations with the James Web Space Telescope" GTO project. The targets were originally 46P/Wirtanen and a target of opportunity Oort cloud comet in Cycle 1, and main-belt comet 313P/Gibbs in Cycle 2. Given JWST's revised launch window of April - June 2019, the Space Telescope Science Institute approved replacing 46P/Wirtanen with 88P/Howell, and shifting 313P/Gibbs from Cycle 2 to Cycle 1. The target of opportunity comet project remains unchanged. These data will be made available to the planetary community immediately, in order to facilitate plans for future comet observations with Webb. See CSN Issue 20, or JWST proposals 1252 and 1253 for details.

Mike Kelley, Univ. Maryland
Stefanie Milam, NASA GSFC
Heidi Hammel, AURA

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

• Geraint H. Jones ^{1, 2}
• Matthew M. Knight ^{3, 4}
• Karl Battams ⁵
• Daniel C. Boice ^{6, 7, 8}
• John Brown ⁹
• Silvio Giordano ¹⁰
• John Raymond ¹¹
• Colin Snodgrass ^{12, 13}
• Jordan K. Steckloff ^{14, 15, 16}
• Paul Weissman ¹⁴
• Alan Fitzsimmons ¹⁷
• Carey Lisse ¹⁸
• Cyrielle Opitom ^{19, 20}
• Kimberley S. Birkett ^{1, 2, 21}
• Maciej Bzowski ²²
• Alice Decock ^{19, 23}
• Ingrid Mann ^{24, 25}
• Yudish Ramanjooloo ^{1, 2, 26}
• Patrick McCauley ¹¹

1. Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, UK
2. The Centre for Planetary Sciences at UCL/Birkbeck, London, UK
3. University of Maryland, College Park, USA
4. Lowell Observatory, Flagstaff, USA
5. Naval Research Laboratory, Washington, D.C., USA
6. Scientific Studies and Consulting, San Antonio, USA
7. Trinity University, San Antonio, USA
8. IAG, Universidade de São Paulo, São Paulo, Brasil
9. University of Glasgow, Glasgow, UK
10. Osservatorio Astrofisico di Torino, INAF, Pino Torinese, Italy
11. Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
12. The Open University, Milton Keynes, UK
13. Max Planck Institute for Solar System Research, Göttingen, Germany
14. Planetary Science Institute, Tucson, USA
15. Massachusetts Institute of Technology, Cambridge, USA
16. Purdue University, West Lafayette, USA
17. Queen’s University Belfast, Belfast, UK
18. Johns Hopkins University Applied Physics Laboratory, Laurel, USA
19. University of Liège, Liège, Belgium
20. European Southern Observatory, Santiago de Chile, Chile
21. Surrey Satellite Technology Ltd, Guildford, UK
22. CBK, Warsaw, Poland
23. Observatoire de Paris, Paris, France
24. EISCAT Scientific Association, Kiruna, Sweden
25. UiT The Arctic University of Norway, Tromsø, Norway
26. Institute for Astronomy, University of Hawai’I, Honolulu, USA

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics.

Open access article.

Space Science Reviews (Published)

DOI: 10.1007/s11214-017-0446-5