The ESA Gaia mission and its promise for cool giant planets

1 ESA UNCLASSIFIED – Releasable to the Public 7/10/2025 Johannes Sahlmann Gaia Project Scientist TITLE OF PRESENTATION The ESA Gaia mission and its promise for cool giant planets 2 Gaia reveals the origin and evolution of the Milky Way • Stellar positions and distances ➡ Galactic structure •Stellar motions ➡ Galactic kinematics • Stellar parameters, compositions, ages ➡ Galactic evolution • Optical all-sky survey with 3 instruments: Astrometry, Photometry, Spectroscopy • Gaia observes ~1% of the stars in the Galaxy • Gaia survey enables rich complementary science Credit: ESA/Gaia/DPAC, Stefan Payne-Wardenaar (source) 3 The Gaia spacecraft is 10 m wide and has 2 telescopes Credit: ESAC (source) 4 Gaia was launched to L2 in December 2013 • 10.5 years of science observations from July 2014 to January 2025 • Gaia was constantly spinning and scanning the sky • Surveying star-like sources, e.g. stars, galaxies, quasars, asteroids, … • Magnitudes range G ≈ 3-21 ESA/CNES/ARIANESPACE Credit: ESA (source) 5 Gaia data flow from the spacecraft to the ESA archive Gaia consortium incl. ESA Credit: ESA (source)Credit: ESA/ATG medialab (source) 6 DR3 2022 There were 3 intermediate Gaia data releases so far •Iterative process of incremental data releases •There is no proprietary period on science data for the Gaia collaboration •https://www.cosmos.esa.int/web/gaia/data • Early DR3 (2020) • Focused Product Release (5 products, 2023) Data timespan; Data quality; Data volume; Number and detail of catalogues DR1 2016 DR2 2018 Credit: ESA/Gaia/DPAC (source) 7 Credit: ESA/Gaia/DPAC, Milky Way impression by Stefan Payne-Wardenaar (source)Credit: ESA/Gaia/DPAC (source) 8 Gaia spacecraft was passivated on 27 March 2025 Credit: ESA/Gaia/DPAC (source) • Gaia exhausted its cold gas and stopped science observations on 15 January 2025 • Gaia was put in a heliocentric orbit and permanently switched off • ESA news release: https://www.esa.int/Enabling_Support /Operations/Farewell_Gaia!_Spacecr aft_operations_come_to_an_end •Additional information: https://www.cosmos.esa.int/web/gaia/ iow_20250327 https://www.cosmos.esa.int/web/gaia/ iow_20250929 • This is not the end of the mission 9 Gaia is a very productive science mission Credit: ESA/Gaia/DPAC (source) 16 Gaia astrometry opens up a new exoplanet window 17 The Gaia collaboration is preparing Gaia Data Release 4 •High quality data releases: science-ready, calibrated, and validated data products; extensive documentation DR1 2016 DR2 2018 DR3 2022 Gaia DR4 (planned December 2026) •5.5 years of data ; ~500 TB •New data products •Timeseries for all sources / instruments •Previews, content, and more •New Science! 18 Gaia DR4 astrometric uncertainties (median value vs. G) DPAC/ CU3/ AGIS/ DPCE team Parallax Proper motion expected improvement surpassed for G<13 expected improvement reached for all G Paraty - 2024.11.19 - 10/27 Proper motion uncertainty Credit: ESA/Gaia/DPAC (source) Upcoming Gaia DR4 is the “nominal mission” data release • Gaia DR4 covers 5.5 years (2014-2020) of Gaia data • More data, longer timespan, better precision, higher accuracy • >2 billion sources • More and new data products, including lower-level data: •Time series of astrometric data + CCD images •Lightcurves: time series of photometric data •Radial velocity time series •Time series of lowand high-resolution spectra •New non-single-source classes, source environment information, crowded field images, and much more • Gaia DR4 will lead to another flurry of discoveries 19 •Landing page: https://www.cosmos.esa.int/web/gaia/data-release-4 •Content page: https://www.cosmos.esa.int/web/gaia/dr4 • Currently incomplete list of >100 data tables and release items. Updates will be made gradually. Overview of Gaia DR4 and its content is public 20 Gaia DR4 preview: astrometric timeseries of Gaia BH3 https://www.cosmos.esa.int/web/gaia/iow_20240416 https://www.esa.int/Science_Exploration/Space_Science/Gaia/Sleeping_giant_surprises_Gaia_scientists Preliminary astrometric timeseries of Gaia BH3 and an orbit-fitting notebook are public: https://github.com/esa/gaia-bhthree Gaia splinter session (Ségransan & Delisle) 21 Gaia DR4 astrometric timeseries are accurate enough for exoplanet detection Gaia DR4 astrometric timeseries “epoch_astrometry” will contain all individual CCD measurements (cf. gaiadr3.sso_observation). CCD-level accuracy limited by calibration errors to ≳80–150 µas at bright end. Epoch astrometry uncertainties ✁Gaia DR4 formal per CCD astrometric uncertainties →50 µas at G↭13 (→15 µas averaged over 9 CCDs) ✁But: total uncertainties limited by calibration errors to →80–150 µas (30–50 µas averaged over 9 CCDs) DPAC/ CU3/ AGIS/ DPCE team Conclusions EAS2025 - 2025.06.26 - 5/23 Credit: ESA/Gaia/DPAC (source) Astrometric precision and accuracy for individual CCD measurements Combination of 9 CCD measurements limited to ≳ 30–50 µas per Gaia Field-of-View transit. Perryman+14 assumed 34 µas for G<13 stars. Credit: ESA (source) 22 Gaia astrometry opens up a new exoplanet window Gaia DR4 discovery space 23 Gaia DR4 will contain an astrometric exoplanet candidate catalog How many exoplanets will Gaia DR4 reveal? •Number detected by the DPAC pipelines? •Number detectable in Gaia DR4 epoch astrometry? •Mass and period range? •Completeness or purity? Twin binary stars can be astrophysical false positives. Mitigated by e.g. •Colour-magnitude modelling (Gaia Collab., Arenou+23) •Observations (e.g. Marcussen & Albrecht 23, Stefánsson+25) •Ensemble analysis (e.g. Sahlmann & Goméz 25) Most of the science will be done by the community •Gaia DR4 astrometric timeseries are a gamechanger •Astrometric accelerations of long-period systems •Combination with other techniques is very powerful Contributions by Bouchy, Greenfield, Handley, Nowak, Parc, Van Zandt, Schlaufman, and others. Gaia splinter session Not to scale Confirmed Exoplanets 24 Gaia Data Release 5 will constitute the mission’s legacy • Gaia DR5 (10.5 years of data) planned not before end of 2030 DR1 2016 DR2 2018 DR3 2022 Gaia DR4 (planned December 2026) •5.5 years of data ; ~500 TB •New data products •Timeseries for all sources / instruments •Previews, content, and more •New Science! Gaia DR5 (Not before end 2030) •10.5 years of Gaia data •~1 PB in ESA archive •Gaia’s legacy •New Science! 25 Gaia and ESA resources at your fingertips • Gaia general information and news releases: https://www.esa.int/Science_Exploration/Space_Science/Gaia • Information for Gaia scientific community: https://www.cosmos.esa.int/web/gaia • Receive Gaia data user notifications by signing up for the Gaia Bulletin emailing list: https://www.cosmos.esa.int/web/gaia/bulletin • Interested in boosting the visibility of your Gaia-related research with an ESA news release? See https://www.cosmos.esa.int/web/gaia/communicating-your-results • Please acknowledge the use of Gaia data in your research: https://www.cosmos.esa.int/web/gaia-users/credits •Information on ESA Archival Research Visitor Programme: https://www.cosmos.esa.int/web/esdc/visitorprogramme (next deadline 10 November 2025) •Information on ESA Research Fellowships in Space Science: https://www.cosmos.esa.int/web/spacescience-faculty/opportunities/research-fellowships (next call expected in the third quarter of 2026)