Learning through research

Lab Insertion Unit

• Spectral analysis of in-situ magnetic field measurements : Cluster and Solar Orbiter observations in the solar wind
  Subject : This LIU deals with simple models of turbulence signal as detected in space plasma measurements. Spectral analysis methods to analyze data of the Cluster mission (at 1 AU) and of the Solar Orbiter mission, closer to the Sun. The students therefore developed a Python based first on a Fourier series analysis, then a Morlet wavelet analysis.
  Team : Youssoupha, Léo under the direction of Olga Alexandrova, LESIA
  Results : Students discovered the physics of turbulence in the solar wind. They first learned how to analyze synthetic signals with Fourier and wavelet transforms, then used these two methods of spectral analysis to identify the energy distribution of the magnetic field in the solar wind observed by the Cluster mission. The routines that were developed can now be used to treat data collected by the Solar Orbiter ESA/mission.
• Oxygen chemistry in the protostellar bowshock of HH54
  Subject : This study of the interstellar medium of galaxies focusses on the physics and chemistry of shocks, in connection with the star formation processes. Shock waves, ubiquitous in the interstellar medium, cause the heating, compression, dissociation, and/or ionization of the gas through which they propagate. Recent observations in the IR to mm domains are used to derive unique constraints on the physics and chemistry of shocks. To answer these questions, students had to interpret infrared and millimetric observations of rotational transitions of atomic hydrogen and atomic oxygen, in order to provide an estimate of the total column density and of the excitation temperature of the two elements.
  Team : Jessica, Itan under the direction of Antoine Gusdorf, LPENS
  Results : Students learned to understand the physical and chemical nature of the bowshock, and subsequently its effect on the interstellar medium surrounding it. They presented the challenges and procedure in measuring and producing excitation diagrams for the rotational transitions of H2 and its column density. They studied two protostellar binary system : they took extinction into account to derive unbiased information. Results were finally limited by the fact they only had access to one spectral line and could not construct an excitation diagram to obtain abundances.
• Functional validation of CubeSat COTS in VEGA room
  Subject : New protocols for CubeSat components dedicated to nanosatellites are developed, in order to prepare scientific teams to assess the right choices and the complexity of their development plan in terms of inhouse tests, system acceptance, or full integration of CubeSats onground and in-flight commissioning. This LIU was more particularly interested in the fine pointing performance of objects in the planetary foreground, to measure the position of a CubeSat by parallax.
  Team : Julien, Salvatore under the direction of Boris Segret, CENSUS
  Results : Students developed a way to read live data from a BiSon64 Sun-Sensor, a component-off -the-shelf bi-directional photo sensor intended for locating the Sun for CubeSats. They used an Arduino Mega to interpret current originating from the solar sensor and performing the calculations to return the two angles down from a vector normal to the photo-sensor’s face.

Internships

• Destabilization of Titan due to Saturn’s tilt
  Subject : This work focuses on regions of instability in Titan’s trajectory and their evolution. The Hamiltonian and the secular Hamiltonian were established to define the equations of motion and equilibrium points of the Saturn-Titan system
  Team : Aurore under the direction of Melaine Saillenfest, IMCCE
  Results : The goal of the internship was to determine the regions of instability for Titan and their evolution. The Hamiltonian and secular Hamiltonian were established to define the equations of motion and equilibrium points of the Saturn-Titan system. The simplified cases of the circular orbit, the far satellite and the near satellite have been largely treated analytically, while the general case has been solved by characterizing the Poincaré surface of the system.
• Energy particles in solar flares : X-ray and radio diagnostics
  Subject : The Solar Orbiter mission (ESA/NASA) has several instruments on board, among which STIX (Spectrometer / Telescope for Imaging X-rays) and RPW (Radio and Plasma Waves). One of the interest of comparing X-ray and radio observations is to characterize particle acceleration during solar flares. The first STIX observations recovered during the commissioning phase provide an approach to future observations, notably for the detection of solar flares.
  Team : Adrien under the direction of Nicole Vilmer, LESIA
  Results : Spectrograms of both RPW and STIX observations in November 2020 were drawn, during which STIX observed many flares, unfortunately without any radio counterpart. The internship work showed that there is some delay between the observational signatures. An analysis of RPW observations was performed to determine the drift rate of the type III burst, aiming at providing the velocity of excited electrons.
• Design of a 325 GHz sub-harmonic mixer as part of the ACCP study
  Subject : GHz and THz heterodyne receivers offer very high spectral resolving powers to resolve molecular lines and understand and characterize planetary atmospheres.
  Team : Estelle under the direction of Jeanne Treuttel, LERMA
  Results : The study carried out during this internship consisted in a critical analysis of the simulations of subharmonic mixers, then a study of performance at 325 GHz. (ACCP : Aerosol, Cloud, Convection and Precipitation)
• Simulating Stellar Streams
  Subject : Stellar streams are over-densities of an ensemble of stars that exists in the Galaxy. They have been observed as well as modeled numerically and theoretically
  They are composed of stars that escaped from either small satellite galaxies or globular clusters. The determination of their structure makes it possible to better understand the Galactic gravitational field. This in turn can allow for a better understanding of the distribution of dark matter in the Galaxy.
  Team : Salvatore under the direction of Paola Di Matteo, GEPI
  Results : Progenitors of stellar streams were analyzed through numerical simulations of 145 globular clusters in the Milky Way. A Galactic potential model consisting of a thick and a thin disc, and a spherical dark matter halo, was used. Simulated stellar streams were compared to those discovered by analysing data from the Gaia space mission.
• Angle based Multiple Cross-Correlation algorithm implementation in ESA’s OPS-Sat
  Subject : The autonomous navigation of nanosats uses the parallactic elements of planetary sources observed against a background of stars. As some scientific projects requires a demanding accuracy better than an arcsecond, specific algorithms must be developed for achieving this goal.
  Team : Youssoupha under the direction of Boris Segret, CENSUS
  Results : This project validated and tested the functional specifications of the pointing system. Many codes have been produced for this purpose, which must be validated in ESA format.
• Predicting the Fractions of Supermassive Black Holes and Active Galactic Nuclei in Dwarf Galaxies using state-of-the-art Cosmological Simulations
  Subject : Most local massive galaxies harbour a supermassive black hole in their center. How they form, grow and evolve is believed to be
  linked to the galaxy in which they reside. All of which are still open questions !
  Team : Houda under the direction of Volonteri / Habouzit, LERMA / MPIA
  Results : This work has investigated the formation and evolution of BHs in dwarf galaxies, focussing on probing for BHs and AGN in the local dwarf regime (z = 0) using six state-of-the-art cosmological simulations compares with recent observational findings. Original results from this work is now published in Haidar et al. 2022, accepted in MNRAS , 2022arXiv220109888H

Gap years

• Type : Research
  Place : LUTh Laboratory, Observatoire de Paris - PSL
  Subject : Centaurus A with Gammapy
  Student : Jessica
  Motivation : With this gap year internship, and before starting a M2 in astrophysics, Jessica wanted to discover the world of research while working in a scientific topic that she wanted to deepen. She completed the six-month internship in a lab with research experience in the space industry
• Type : Discovering corporate world
  Place : Thales Alenia Space
  Subject : Development of an AI tool to measure WCET (Worst Case Execution Time) and optimize an on-board software
  Student : Léo
  Motivation : To approach the M2 engineering course with confidence, Léo wanted to have a gap year in order to discover the space agencies and industries, with an internship at CNES followed by another internship in one of the major industrial groups in the sector.
• Type : Training
  Place : Lund University, Sweden
  Subject : Learning Swedish, with a scientific internship in a laboratory at Lund University
  Student : Antoine
  Motivation : Antoine learned Swedish by himself. He has identified that a gap year in a scientific Master’s degree in Lund brings him international experience, allows him to perfect his learning of Swedish and to discover the astrophysical topics he wishes to develop.