Cometary Science Newsletter

September 2017
Michael S. P. Kelley (

Conference Announcements

Announcements for cometary conferences or workshops. Limited to 2000 characters.

Diversis mundi (OPS-III): The Solar System in an Exoplanetary context

Santiago, Chile, March 5 - 9, 2018
Conference email

This one-week workshop has the objective to bring together the solar system and exoplanet scientific communities and explore how the expertise and recent discoveries in those fields can feed and contrast each other. Strong interactions and collaborations between both communities are essential, as the discovery of exoplanetary systems with a large variety of architectures can teach us about the formation and history of our own solar system, and the deep understanding of our own environment can help us towards our search for life traces outside of the solar system. Various aspects such as formation and architecture of planetary systems, small components of planetary systems, or planetary atmospheres and biomarkers will be discussed from both points of view and in the context of the forthcoming new observational facilities. During this workshop, emphasis will be made on developing new ideas and encouraging synergies between both fields, and plenty of time will be left for discussion and interactions. The main topics and related questions are:

  1. Formation of planetary systems and their components
  2. Architecture and evolution of planetary systems
  3. Small components of planetary systems
  4. Atmospheres and biomarkers

The workshop will be held at the ESO office in Vitacura (Santiago de Chile) from March 5 to 9, 2018. The venue can host a maximum of 110 participants. The conference fee will include coffee breaks, lunch, and welcome folder.

Refereed Articles

Abstracts of articles in press or recently published. Limited to 3000 characters.

Ground-based monitoring of comet 67P/Churyumov-Gerasimenko gas activity throughout the Rosetta mission

  • Opitom, C. 1
  • Snodgrass, C. 2
  • Fitzsimmons, A. 3
  • Jehin, E. 4
  • Manfroid, J. 4
  • Tozzi, G. P. 5
  • Faggi, S. 5
  • Gillon, M. 4
  1. European Southern Observatory, Avda. Alonso de Cordova 3107 Vitacura, Casilla 19001, Santiago de Chile, Chile
  2. School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK 0000-0001-9328-2905
  3. Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK
  4. Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, allée du 6 Août 17, B-4000 Liège, Belgium
  5. INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50 125 Firenze, Italy

Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active gas species and imaging of the overall dust coma. We present more than 2 yr of observations performed with the FORS2 low-resolution spectrograph at the VLT, TRAPPIST and ACAM at the WHT. We focus on the evolution of the CN production as a tracer of the comet activity. We find that it is asymmetric with respect to perihelion and different from that of the dust. The CN emission is detected for the first time at 1.34 au pre-perihelion and production rates then increase steeply to peak about 2 weeks after perihelion at (1.00 ± 0.10) × 1025 molecules s-1, while the post-perihelion decrease is more shallow. The evolution of the comet activity is strongly influenced by seasonal effects with enhanced CN production when the Southern hemisphere is illuminated.

Monthly Notices of the Royal Astronomical Society (Published)

DOI: 10.1093/mnras/stx1591 NASA ADS: 2017MNRAS.469S.222O

The Unusual Apparition of Comet 252P/2000 G1 (LINEAR) and Comparison with Comet P/2016 BA14 (PanSTARRS)

  • Jian-Yang Li (李荐扬) 1
  • Michael S. P. Kelley 2
  • Nalin H. Samarasinha 1
  • Davide Farnocchia 3
  • Max J. Mutchler 4
  • Yanqiong Ren (任彦瓊) 5
  • Xiaoping Lu (盧曉平) 5
  • David J. Tholen 6
  • Tim Lister 7
  • Marco Micheli 8
  1. Planetary Science Institute, 1700 E. Ft. Lowell Rd., Suite 106, Tucson, AZ 85719, USA
  2. Department of Astronomy, University of Maryland, College Park, MD 20742, USA
  3. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
  4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218-2463, USA
  5. Macau University of Science and Technology, Macau, China
  6. Institute for Astronomy, University of Hawai’i, Honolulu, HI 96822, USA
  7. Las Cumbres Observatory, 6740 Cortona Drive Ste. 102, Goleta, CA 93117, USA
  8. ESA SSA-NEO Coordination Centre, 00044 Frascati (RM), Italy

We imaged Comet 252P/2000 G1 (LINEAR) (hereafter 252P) with the Hubble Space Telescope and both 252P and P/2016 BA14 (PanSTARRS) (hereafter BA14) with the Discovery Channel Telescope in March and April 2016, surrounding its close encounter to Earth. The r'-band Afρ of 252P in a 0.2"-radius aperture were 16.8±0.3 and 57±1 cm on March 14 and April 4, respectively, and its gas production rates were: Q(OH) = (5.8±0.1)×1027 s-1, and Q(CN) = (1.25±0.01)×1025 s-1 on April 17. The r'-band upper limit Afρ of BA14 was 0.19±0.01 cm in a 19.2"-radius aperture, and Q(CN) = (1.4±0.1)×1022 s-1 on April 17, 2017. 252P shows a bright and narrow jet of a few hundred kilometers long in the sunward direction, changing its projected position angle in the sky with a periodicity consistent with 7.24 hours. However, its photometric lightcurve is consistent with a periodicity of 5.41 hours. We suggest that the nucleus of 252P is likely in a non-principal axis rotation. The nucleus radius of 252P is estimated to be about 0.3±0.03 km, indicating an active fraction of 40% to >100% in its 2016 apparition. Evidence implies a possible cloud of slow-moving grains surrounding the nucleus. The activity level of 252P in the 2016 apparition increased by two orders of magnitude from its previous apparitions, making this apparition unusual. On the other hand, the activity level of BA14 appears to be at least three orders of magnitude lower than that of 252P, despite its ten times or larger surface area.

The Astronomical Journal (In press)

NASA ADS: 2017arXiv170805190L arXiv: 1708.05190