LIRA
Laboratory for Instrumentation and Research in Astrophysics

LIRA, a pioneer in astrophysics and instrumentation, pushes back the frontiers of knowledge

LENS: LIRA – Weekly Highlight

The fastest star in the Milky Way!

31 August 2026

An international team has discovered S301, a star that is breaking all records in its orbit around Sagittarius A*, the supermassive black hole at the centre of our Galaxy. It travels at 25,000 km/s – 8 per cent of the speed of light – and comes within just 12 astronomical units of the black hole, roughly the distance between the Sun and Saturn.

This exceptional proximity makes S301 a new laboratory for general relativity. Its orbit could enable the detection of the effect of the black hole’s rotation on space-time and, ultimately, allow for a direct measurement of the rotation of Sagittarius A*. It could then provide a new test of general relativity in one of the most extreme environments in our Galaxy.

This discovery is the result of several decades of technical progress to which LIRA has actively contributed: adaptive optics systems, the development of GRAVITY and subsequently GRAVITY+, new methods of data analysis, and numerical tools for comparing observations with theoretical predictions. These advances now make it possible to detect stars that are ever fainter and ever closer to the black hole.

Credit: ESO/Collaboration GRAVITY
SEMINAR Tuesday 8 September 2026 14:00
Séminaires du pôle Étoiles et Galaxies
Eloisa Poggio : The Milky Way through Gaia’s eyes: morphology and kinematics of the Galactic disc
SEMINAR Friday 18 September 2026 11:00
Séminaires du pôle Systèmes Exoplanétaires
Jennifer P. Lucero (PhD student, Instituto de Astrofísica e Ciências do Espaço, Portugal) : Using the Sun to Understand the Effects of Stellar...
SEMINAR Friday 30 October 2026 11:00
Séminaires du pôle Systèmes Exoplanétaires
Bin B. Ren (Professor, Xiamen University, China) : A Multi-Epoch VLT/SPHERE Protoplanetary Disk Imaging Survey — SAFFRON

Presentation

LIRA, a CNRS joint research unit at Paris Observatory, is a laboratory of excellence in astrophysics and instrumentation. It studies astrophysical objects, from the Solar System to our Galaxy and beyond, through five thematic areas. Through international collaboration and instrumental innovation, it pushes back the frontiers of science and contributes to the training and dissemination of knowledge.

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Our projects

MIRS on the JAXA MMX mission

The Martian Moons eXploration (MMX) mission of JAXA (Japan Aerospace Exploration Agency) is the first sample-return mission from the Phobos satellite. It also includes an exploration of the Martian system. The mission’s primary objective is to decipher the origin of Martian moons, which will provide important information on planet formation and the conditions for the emergence of water on Earth-like planets.

The MIRS (MMX InfraRed Spectrometer) instrument, developed under the leadership of LESIA (now LIRA), is an imaging spectrometer that will characterize the composition of the Martian system and help select candidate sites for sample collection.

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GRAVITY+

The GRAVITY instrument, installed on the European Southern Observatory’s Very Large Telescope Interferometer (VLTI/ESO), has produced spectacular and transformative results on the supermassive black hole at the centre of the Milky Way, the active nuclei of other galaxies, proto-planetary disks around young stars and exoplanets. GRAVITY+ aims to modernise both VLTI and GRAVITY to make them ≈ 100 times more sensitive, while increasing sky coverage by a factor of ≈ 100, and contrast in the vicinity of bright objects by a factor of ≈ 10. These gains will benefit all the VLTI’s current and future instruments for the next 20 years, and will perpetuate it as a unique infrastructure in the world.

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Contacts

Contacts

Postal address
Observatoire de Paris
5, place Jules Janssen
92195 Meudon

Phone
01 45 07 77 01

Mail
contact.lira@obspm.fr

Meudon site

LIRA
Observatoire de Paris
5, place Jules Janssen
92195 MEUDON Cedex

How to get to Meudon

Paris site

LIRA
Observatoire de Paris
77, Avenue Denfert-Rochereau
75014 Paris

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Cergy site

LIRA - Site de Neuville II
UFR Sciences et Techniques - Département de physique
5, mail Gay Lussac
95000 Neuville-sur-Oise

How to get to Cergy