LERMA UMR8112

Laboratoire d’Études du Rayonnement et de la Matière en Astrophysique et Atmosphères



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Open PHD position in Astrophysics

par Valerie Audon - publié le

(October 2017)

Subject :

Sulphur-bearing molecules in star forming regions : Observational and laboratory investigations.

Supervisors :

L.E. Kristensen (Niels Bohr Institute & Natural History Museum of
Denmark, University of Copenhagen), F. Dulieu (LERMA, University of Cergy-Pontoise & Paris Observatory)

Thesis work.

The thesis aims at tackle the problem sulphur chemistry in star forming regions and in particular the of the origin of H2S in ices, as well as its link with other observed forms in shocks. One half of the work will be devoted to laboratory astrophysics. Using the experimental set-ups located in Neuville-sur-Oise (FORMOLISM and VENUS), the synthesis of H2S and the properties of the ice formed will be investigated. The experimental work will be done with the help of the team (https://lerma.obspm.fr/spip.php?article48). The other part will be devoted to the analysis of observations of sulphur bearing molecules in shocks, and will be mostly done in Copenhagen.

Practical details.

The grant will be a doctoral contract which is a 3 years working contract following
French/European regulations (1758€ monthly gross salary). The student will follow the courses and regulations of Doctoral School of Science and Engineering of Paris Seine University, (ED 417 http://www.collegedoctoral.u-cergy.fr/). The starting date is October 1st 2017 or as soon as possible thereafter. It is funded by ’Initiative excellence Paris Seine’

Application.

Applicant must have a master degree in Science, especially in Astrophysics, Physics or Chemistry. An experience (Internship, master diploma...) in radioastronomy or
experimental physics would be an effective positive aspect of the application.

Applicant must have excellent communication skills in English (oral and written), which will be the working language, although student will follow French language training (part of Doctoral School educational program), and may even learn Danish, Italian and few others languages with the team crews if motivated.

Applications should be constituted of a detailed CV, a letter of motivation and a letter of intent. The candidate should furthermore arrange for a recommendation letter from a professor familiar with the applicant to be sent to both Pr Dulieu and Dr Kristensen.
Applications received before 5th of september will receive full consideration.

More details : francois.dulieu@u-cergy.fr or lars.kristensen@nbi.ku.dk

Séminaires à venir

Vendredi 19 juillet 2019, 14h00
Salle de l'atelier, Paris
Magnetic fields in Young Protostellar Disks and Jets, and some Astro-chemistry
Chin Fei Lee
ASIAA, Taiwan
résumé :
Magnetic fields in Young Protostellar Disks and Jets, and some Astro-chemistry
Chin Fei Lee, ASIAA Taiwan

I will present our recent ALMA observations towards 3 young protostellar
systems, reporting the possible field morphology in their disks and jets.
In particular, I will report the field morphology implied from the dust
polarizations and SiO line polarizations, and discuss the possible toroidal
and poloidal fields in the disks and jets. I will also discuss the
formation process and the growth of the protostellar disks, and the possible
magnetic braking that reduces the angular momentum in the envelope.
Interestingly, more than 10 organic molecules including prebiotic molecules
are detected in the atmosphere of one of the disks. I will compare their
abundances to those in the hot corinos around low-mass protostars and touch
on the possible formation mechanism of those molecules. Some of the
molecules seem to be formed on CO icy grains and some in the gas phase.
 
Vendredi 20 septembre 2019, 14h00
Atelier, Paris
Challenging a Newtonian prediction through Gaia wide binaries
Xavier HERNANDEZ
UNAM, Mexico
résumé :
Under Newtonian dynamics, the relative motion of the components of a binary star should follow a Keplerian scaling with separation. Once orientation effects and a distribution of ellipticities are accounted for, dynamical evolution can be modelled to include the effects of Galactic tides and stellar mass perturbers. This furnishes a prediction for the relative velocity between the components of a binary and their projected separation. After reviewing recent work evidencing the existence of a critical acceleration scale in Elliptical Galaxies and Globular Clusters, I will show new results showing such a phenomenology in Gaia wide binaries using the latest and most accurate astrometry available. The results are consistent with the Newtonian prediction for projected separations below 7000 AU, but inconsistent with it at larger separations, where accelerations are expected to be lower than the critical a0 value of MONDian gravity. This result challenges Newtonian gravity at low accelerations and shows clearly the appearance of gravitational anomalies of the type usually attributed to dark matter at galactic scales, now at much smaller stellar scales.


 
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