A collision of the Milky Way with a small galaxy accurately dated by the study of the star ν Indi

ν Indi is a bright star (visual magnitude mv = 5.3) visible with the naked-eye from the southern hemisphere. By using ground data (ESO telescopes), space data (Gaia and Tess missions) and by combining very diverse spectroscopic, astrometric, kinematic or asteroseismological information, an international team including two researchers from the Department of Astrophysics / AIM Laboratory of CEA-Saclay was able to determine the epoch, between 11.6 and 13.2 billion years ago, of a collision between our galaxy and a small dwarf galaxy, Gaia-Enceladus. This work is published in the journal Nature Astronomy, January 2020.

Dense molecular filaments are the cradles of stars

An international team led by the Astrophysics Department-AIM Laboratory of CEA-Irfu has just obtained new clues about the origin of star mass distribution, combining observational data from the large interferometer ALMA and the APEX radio telescope operated by the European Austral Observatory (ESO) and the Herschel Space Observatory. Thanks to ALMA, the researchers have discovered in the so-called Cat's Paw Nebula, located at about 5,500 light-years, the presence of protostellar dense cores much more massive than those observed in the solar vicinity. Researchers have shown that there is a close link between the mass distribution of interstellar filaments and the mass distribution of stars. The density - or mass per unit length - of the parent filaments is the crucial parameter that controls the masses of newly-formed stars. This discovery provides a key clue to the origin of stellar masses. These results are published in three articles of the journal Astronomy & Astrophysics.

Sounding the cosmic dust around proto-stars

An international team led by researchers from the CEA Paris-Saclay Astrophysics Department (DAp) have probed for the first time the dust envelopes surrounding stars in formation (so-called Class 0 protostars) thanks to the large interferometer NOEMA (former Plateau de Bure, France). Surpisingly, the researchers discovered the presence of large grains whose size grows as one gets closer to the central star. The presence of such large grains, already forms a few 10000 years after the beginning of the initial gas collapse is extremely unexpected. These grains are the building blocks from which planets will be formed. These results could thus call for a major revision of the timeline and timescales to form planets. These conclusions are published in Astronomy & Astrophysics.

Lisa Bugnet is one of 35 young women researchers who won the L'Oréal-Unesco Fellowships for Women in Science in 2019. As an asteroseismologist at the Dynamic Laboratory of Stars, (Exo)planets and their Environment of the DAP/Irfu, she uses seismic waves emitted by stars to probe their heart and understand their evolution from birth to the end of their life.

An international collaboration, involving the Astrophysics Department-Laboratory AIM of CEA irfu, participated in the study of an exoplanetary system, Kepler-107 and revealed an amazing distribution of its 4 planets of which two seem potentially resulting from a giant impact. Thanks to asteroseismology (the study of star vibrations) and the modeling of planetary transits, researchers have been able to determine the mass and radius of the central star and its planets with great precision. and highlighted the unusual density of one of the planets. This anomaly can be explained by a giant collision between planets, probably similar to the one that affected the Earth in the past to form the Moon. These results are published in the journal Nature Astronomy of Februrary 4th, 2019.

At the World SuperComputing'17 Congress in Denver (United States), which brings together more than 10,000 HPC experts, CEA researchers, members of an international team, received the "2017 HPCWire Publishers Award" for outstanding results based on high-performance computing that unlock the secrets of star magnetic cycles (HPCWire Editors Choice Awards 2017, Top HPC-enabled Scientific Achievement). HPCWire is the world leader in new sources of information in the field of supercomputing.

Star formation in the filamentary Aquila and Taurus molecular clouds

Based on observations of nearby molecular clouds with the Herschel space observatory, recently large samples of future stars were detected in the form of dense cores. The properties of these compact seeds and their connection with interstellar filaments reveal us the earliest key stages of stars and the way of low-mass star formation.

Among several cloud complexes along the Gould Belt (see image below) the Aquila and Taurus regions were targeted. While the star formation in Aquila was relatively unexplored until recently, the Taurus cloud with its main filaments is well known. The Aquila Rift lies above the Galactic plane at the distance of about 260 parsec (approximately 850 light-years from the Sun). The Taurus region is more nearby, it seems to sit in the wall of the Local Bubble - a cavity, surrounding the Solar System- at 140 parsec (or 450 light-years) from us. 

Promising scientific results for the largest space telescope

One year on from the launch of the Herschel European satellite, the European Space Agency (ESA) is carrying out an initial scientific assessment of the mission, starting with the first symposium of Herschel scientific results, held from 4th to 7th May on the ESTEC site in Noordwijk (Netherlands).
The scientific community has been analyzing the initial data received since Herschel was declared 'science-ready' in September 2009. More than 400 scientists gathered at ESTEC to present their initial results, which have lived up to everyone's expectations. These results are due for publication in a special issue of Astronomy & Astrophysics in the autumn of 2010, and are mentioned in a CNRS-CEA press release.
The French community is deeply involved in the Herschel project, accounting for 25% of the participants, including several teams from the Astrophysics Department of the CEA-IRFU-AIM Laboratory.

The unexpected shape of the Saturn moons inside the rings (7 Decembre 2007)

The high resolution images provided by the Cassini spacecraft have uncovered a surprising shape for two small Saturn satellites located inside the rings of the giant planet. An international team, leaded by Sébastien Charnoz and André Brahic from the Service d'Astrophysique (SAp) of CEA/DSM/DAPNIA and laboratoire AIM (CNRS, Université Paris Diderot), have just shown that the Pan and Atlas satellites, two small moons with only a 30 km radius, are circled at their equator by an important padding making them looking like "flying saucers". Thanks to numerical simulations able to reproduce the collisions among particles taking place inside the Saturn rings, the astronomers have now gain new indications that the small bodies have indeed "grown" inside the rings. They constitute a new evidence that the Saturn rings originate from the cataclysmic desintegration of a bigger satellite or comet.
These results are published in Science of 7 décembre 2007.

For details and more information in French : click HERE 


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