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A scientific guide to Gaia Astrophysical Parameters

Figure 1. Gaia DPAC CU8

Gaia's Data Processing and Analysis Consortium consists of 9 coordination units, each with their own responsibilities in the preparation of a Gaia data release. Gaia's coordination unit 8 is responsible for the production of the astrophysical parameters. A webinar series was held early 2023 to explain the different processing modules and their results as published in Gaia's Data Release 3 (as released in June 2022). This webinar series follows in the footsteps of the video series called CU8 Pills of Science as prepared by Gaia DPAC CU8 for publication along with the Gaia Data Release 3 papers. Find here the recorded videos from the Gaia DPAC CU8 webinar series. The presentations can also be downloaded from the main seminar website and are available from the Gaia DPAC CU8 youtube channel ​​​​​​.

General Stellar Parametrizer from Photometry or GSP-Phot

This module aims to derive a detailed characterisation of the single stars using the low-resolution BP/RP spectra, the apparent G magnitude and parallax, as measured by Gaia. More information from the Gaia Data Release Documentation on the General Stellar Parametrizer from Photometry.

Presented in this video is the GSP-Phot module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by R. Andrae for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/R. Andrae.

Extended Stellar Parametrizer for Hot Stars or ESP-HS, and Extended Stellar Parametrizer for Emission-Line Stars or ESP-ELS

This module aims to derive the astrophysical parameters of stars hotter than 7500 K. ESP-ELS stands for Extended Stellar Parametrizer for Emission-Line Stars. This module aims to identify the XP spectra of seven classes of emission-line stars (ELS): Be stars, Herbig Ae/Be stars, T Tauri stars, active M dwarf stars, Wolf Rayet WC stars & WN stars, and planetary nebula. More information from the Gaia Data Release Documentation on the Extended Stellar Parametrizer for Hot Stars.

Presented in this video are the ESP-HS and ESP-ELS modules, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by Y. Fremat for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/Y. Fremat.

Extended Stellar Parametrizer for UltraCool Dwarfs or ESP-UCD

The module aims to identify Ultracool Dwarfs and produce estimates of their effective temperatures based on their RP spectra. More information from the Gaia Data Release Documentation on the Extended Stellar Parametrizer for UltraCool Dwarfs.

Presented in this video is the ESP-UCD module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by L. Sarro Baro for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/L. Sarro Baro.

Extended Stellar Parametrizer for Cool Stars or ESP-CS

This module aims to infer a chromospheric activity index from the analysis of the Ca II IRT (calcium infrared triplet) in the RVS spectra. More information from the Gaia Data Release Documentation on the Extended Stellar Parametrizer for Cool Stars.

Presented in this video is the ESP-CS module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by A. Lanzafame for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/A. Lanzafame.

Final Luminosity Age Mass Estimator or FLAME

This module aims to produce the stellar mass and evolutionary parameters for each Gaia source. More information from the Gaia Data Release Documentation on the Final Luminosity Age Mass Estimator.

Presented in this video is the FLAME module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by O. Creevey for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/O. Creevey.

General Stellar Parametrizer from Spectroscopy or GSP-Spec

The module estimates the stellar atmospheric parameters, individual chemical abundances and Diffuse Interstellar Band (DIB) parameters from combined RVS spectra of single stars. More information from the Gaia Data Release Documentation on the General Stellar Parametrizer from Spectroscopy.

Presented in this video is the GSPSpec module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by P. A. Palicio for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/P.A. Palicio.

Discrete Source Classifier or DSC

The module classifies Gaia sources probabilistically into five classes: quasar, galaxy, star, white dwarf, physical binary star. More information from the Gaia Data Release Documentation on the Discrete Source Classifier.

Presented in this video is the DSC module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by C.A.L. Bailer Jones and S. Jamal for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/C.A.L. Bailer-Jones and S. Jamal.

Unresolved Galaxy Classifier or UGC

This module aims to estimate the redshift of unresolved galaxies observed by Gaia. More information from the Gaia Data Release Documentation on the Unresolved Galaxy Classifier.

Presented in this video is the UGC module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by D. Hatzidimitriou for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/D. Hatzidimitriou.

Total Galactic Extinction or TGE

This module aims to provide the total Galactic extinction map at different resolutions. More information from the Gaia Data Release Documentation on the Total Galactic Extinction.

Presented in this video is the TGE module, developed by Gaia DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by R. Drimmel and D. Marshall for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/R. Drimmel and D. Marshall.

Quasar Classifier or QSOC

The module aims to determine the redshift of the sources that are classified as quasars by the DSC module. More information from the Gaia Data Release Documentation on the Quasar Classifier.

Presented in this video is the QSOC module, developed by DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by L. Delchambre for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/L. Delchambre.

Outlier Analysis or OA

The module aims to complement the overall classification performed by the DSC module by processing those objects with a lower probability classification from DSC. It aims to help in the photometric processing by detecting artefacts, improving DSC classification and analysing weird, infrequent objects. Specifically, it deals with the analysis of those sources that are assigned DSC combined probabilities below a given threshold for all the considered classes. More information from the Gaia Data Release Documentation on the Outlier Analysis.

Presented in this video is the OA module, developed by DPAC CU8, and its outputs in Gaia DR3. The video is the recording of the webinar by D. Garabato for the "A scientific guide to Gaia Astrophysical Parameters" webinar series. Video credit: Gaia/DPAC/CU8/D. Garabato.

Credits: ESA/Gaia/DPAC/CU8

[Published: 13/09/2023]