Cometary Science Newsletter

October 2023
Michael S. P. Kelley (

ESA Archival Research Visitor Programme

To increase the scientific return from its space science missions, the European Space Agency (ESA) welcomes applications from scientists interested in pursuing research projects based on data publicly available in the ESA Space Science Archives (

The ESA Archival Research Visitor Programme is open to scientists, at all career levels, affiliated with institutes in ESA Member States and Collaborating States. Early-career scientists (within 10 years of the PhD) are particularly encouraged to apply. Applications by PhD students are also welcome.

During their stay, visiting scientists will have access to archives and mission specialists for help with the retrieval, calibration, and analysis of archival data. In principle, all areas of space research covered by ESA science missions can be supported.

Residence lasts typically between one and three months, also distributed over multiple visits. Research projects can be carried out at ESAC (Madrid, Spain) and at ESTEC (Noordwijk, Netherlands). To offset the expenses incurred by visitors, ESA covers travel costs from and to the home institution and provides support for lodging expenses and meals.

Applications received before 1 November 2023 will be considered for visits in spring and summer 2024.

For further details, including areas of research and contact information, please refer to:

or write to the programme coordinators at

Conference Announcements

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

What was that? – An ESO workshop on planning follow up for transients, variables, and solar system objects in the era of LSST

We invite participants to a workshop to prepare for effective follow up of alerts from the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) using European Southern Observatory (ESO) telescopes. This workshop will cover a broad range of science topics associated with variable, transient or moving objects that will be discovered in vast numbers by the LSST. We intend to mix overview talks on how LSST will impact these fields, lessons learned from previous surveys and ESO programmes, the expected yield of discoveries from LSST, and the planned capabilities of ESO facilities in the coming decade. We will have talks that introduce the LSST, its alert brokers and other tools and services designed to enable follow-up observations. The workshop will include dedicated breakout sessions to plan broad community follow up programmes at ESO.

The workshop will take place at ESO headquarters in Garching, Germany, between the 22nd and 26th of January 2024. In person attendance is encouraged to facilitate collaboration building, but virtual attendance will also be supported. Further information can be found at

The registration deadline will be 30 November 2023.

Refereed Articles

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

  • Z M Lewis 1
  • A Beth 1
  • K Altwegg 2
  • M Galand 1
  • C Goetz 3
  • K Heritier 1
  • L O’Rourke 4
  • M Rubin 2
  • P Stephenson 1
  1. Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK
  2. Physikalisches Institut, University of Bern, CH-3012 Bern, Switzerland
  3. Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne NE1 8ST, UK
  4. ESAC, European Space Agency, Madrid, 28692, Spain

The European Space Agency/Rosetta mission escorted comet 67P/Churyumov-Gerasimenko and witnessed the evolution of its coma from low activity (~2.5-3.8 au) to rich ion-neutral chemistry (~1.2-2.0 au). We present an analysis of the ion composition in the coma, focusing on the presence of protonated high proton affinity (HPA) species, in particular NH4+. This ion is produced through the protonation of NH3 and is an indicator of the level of ion-neutral chemistry in the coma. We aim to assess the importance of this process compared with other NH4+ sources, such as the dissociation of ammonium salts embedded in dust grains. The analysis of NH4+ has been possible thanks to the high mass resolution of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Double Focusing Mass Spectrometer (ROSINA/DFMS). In this work, we examine the NH4+ data set alongside data from the Rosetta Plasma Consortium instruments, and against outputs from our in-house ionospheric model. We show that increased comet outgassing around perihelion yields more detections of NH4+ and other protonated HPA species, which results from more complex ion-neutral chemistry occurring in the coma. We also reveal a link between the low magnetic field strength associated with the diamagnetic cavity and higher NH4+ counts. This suggests that transport inside and outside the diamagnetic cavity is very different, which is consistent with 3D hybrid simulations of the coma: non-radial plasma dynamics outside the diamagnetic cavity is an important factor affecting the ion composition.

Monthly Notices of the Royal Astronomical Society (Published)

DOI: 10.1093/mnras/stad1787 NASA ADS: 2023MNRAS.523.6208L

The activity of 119 comets

  • Betzler, A.S. 1
  • Diepvens, A. 2
  • de Sousa, O. F. 3
  1. Centro de Ciência e Tecnologia em Energia e Sustentabilidade, Universidade Federal do Recôncavo da Bahia, Feira de Santana, BA 44.085-132, Brazil
  2. Olmen Observatory C23, B-2491 Olmen, Belgium
  3. Centro de Formação de Professores, Universidade Federal do Recôncavo da Bahia, Amargosa, BA 45.300-000, Brazil

This study examines photometric data from 119 comets observed between 2011 and 2020 at the Olmen Observatory in Balen, Belgium, using R- and G-band filters. Applying the q-exponential distribution from Tsallis' nonextensive mechanics, we find that our sample of short-period (SP) and long-period (LP) comets is complete for objects with an absolute magnitude of H0 ≤ 11.2 and ≤ 8.7, respectively. These magnitude constraints were used to perform a statistical analysis of the physical parameters describing these populations. LP comets generally have brighter absolute magnitudes and higher activity (median × 15.4) compared to SP comets. The secular light curves of these comets are symmetric about perihelion. Cometary activity was divided into four categories ("unusual,"' "typical,"' "moderate,"' and "strong"') based on the Afρ(0) parameter at perihelion, with about 72.7 and 53.6% of the SP and LP comets falling into the "typical" classification.The distribution of peak magnitudes ΔM for outbursts is similar for SP and LP comets, with a median value of -1.0 and a range of -0.2 to -2.90 magnitudes. On average, there are 0.6 and 1.0 outbursts per comet for comets SP and LP, respectively. This result suggests that these events are somewhat more frequent for the LP comets. There is no evidence of periodicity in the frequency of outbursts based on our data. The peak magnitude ΔM of an outburst does not correlate with Afρ(0).

Monthly Notices of the Royal Astronomical Society (Published)

DOI: 10.1093/mnras/stad2696 NASA ADS: 2023MNRAS.526..246B