Expert on asteroids visits Cerro Calán

For five weeks, Damya Souami, astronomer of the Paris-Meudon Observatory (France) and member of the Lucky Star team, will be at the National Astronomical Observatory of Cerro Calán, as supported by the “Action Fédératrice Gaia”.

The objective of her visit is to perform high-precision astrometry of small NEAs (Near Earth Asteroids), objects ranging in size from a few kilometers to a few hundred meters. “My goal is to predict the occultations by these objects”, says Souami.

The scientist’s priority is to apply these new algorithms to the Didymos asteroid, which is the target of the DART mission (NASA), launched in the early hours of November 24. “My collaborators and I intend to have at least one occultation before impact, and a few more just after impact, and thus be able to assess the effect of DART on Didymos’ orbit.”

Souami is a member of the DART/Hera research team, and is part of the group in charge of ground tracking of the Didymos system, the results of which will be crucial to the success of the mission. “Our goal is to evaluate the effect of the DART kinetic impactor by measuring the change in the rotation period of this binary asteroid”, she reveals.

Hera, for its part, is the mission led by the European Space Agency, which will be launched in 2024, in order to study the consequences of DART’s impact on Dimorphos (Didymos’ satellite).

Her time in Calan

At Calán, Dr. Souami is working with Professor René Méndez, academic of the Department of Astronomy, who is a specialist in high-precision astrometry, and also with Dr. Sébastien Bouquillon, from the French-Chilean Laboratory of Astronomy, FCLA, who is the developer of the Gaia-GBOT (“Ground Based Optical tracking”, system in charge of the tracking of the Gaia probe).

About her work with Méndez, the researcher points out that, “He is one of the world’s leading experts in high-precision astrometry and parallax measurement. We knew each other from a distance since 2018, we were supposed to meet in Paris in March 2020, but our meeting was delayed as were many other projects. René’s experience with high-precision astrometry and parallax measurement is crucial for the success of our joint work”, she assures.

Souami further gives details of the research: “In Calan we use the expertise we have developed together with my collaborators, in terms of high-precision astrometry in particular for Gaia-GBOT and the tracking of the Gaia satellite along its orbit with an uncertainty of ∼20 milliseconds of arc (∼ 150 m along Gaia’s orbit)”, she says.

Since successfully predicting stellar occultation by NEAs requires higher precision in astrometry that benefits from the Gaia probe’s stellar catalogs, for which, explains the astronomer, “we need to take into account weak effects such as those due to differential chromatic refraction (DCR)”.

A promising career

Until October of this year, Souami was a postdoctoral fellow at the Paris-Meudon Observatory, but she is now a research affiliate at Paris-Meudon Observatory. Prior to that, she completed a ‘Doctoré’ at Pierre and Marie Curie University, now renamed Sorbonne University, in Paris. “However, I completed my PhD studies at the SYRTE department of the Paris Observatory under the supervision of Professor Jean Souchay and the co-supervision of Professor Anne Lemaître of the Université de Namur in Belgium”, she adds.

About her area of research, she points out that “what interests me most is to understand the origin and evolution of the solar system and planetary systems in general. To do so, I make use of different tools from planetary sciences and celestial mechanics”.

“For example, I am interested in the physical characterization of small solar system objects going from the inner solar system with Near-Earth Asteroids (NEAs) to the outer solar system Trans-Neptunian Objects (TNOs) and beyond, with the goal of better understanding their origin and constraining their dynamical evolution”, she says.

Finally, Damya Souami, Ph.D., reaches out to the observing community in Chile: “Stellar occultations require the use of several telescopes across the projected path on the Earth’s surface. Most of our observing campaigns are possible thanks to the involvement and efforts of the amateur community at large. Small telescopes equipped with fast cameras and good absolute time accuracy are an advantage for most of our campaigns. Any of you with a sufficiently sensitive fast camera (at least a few images per second), a guaranteed absolute time precision of a few milliseconds (nowadays easily obtainable with GPS) can contribute to science, even with a 20 cm telescope. More information about our campaigns can be found in the following link“.