[Astronomy seminar] Reminder: Astronomy departmental seminar Friday October 13 at 10:30am - Guillaume Guiglion (ZAH/ LSW, MPIA)

[Astronomy seminar announcements]

Dear all,

This is a reminder of the weekly SU astronomy departmental seminar that will take place in about 20 minutes, at 10:30am in room FC61 (AlbaNova building, 6th floor) and on zoom (https://stockholmuniversity.zoom.us/s/61002076352). As usual, we encourage you to attend in person if possible.

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Speaker:  Guillaume Guiglion (ZAH/ LSW, MPIA)

Title: Machine-learning for stellar spectroscopy: from RAVE to Gaia-RVS & 4MOST

Event: https://indico.fysik.su.se/e/guillaume-guiglion

Abstract:

In this seminar, I will present recent developments in the field of machine-learning applied to stellar spectra in the context of large scale spectroscopic surveys, such as Gaia-ESO and RAVE. I will particularly focus on Gaia DR3, which provided the community with approximately one million RVS spectra covering the CaII triplet region. One third of the spectra have a signal-to-noise ratio from 15 to 25 per pixel. I will demonstrate that precise parametrization can be achieved for such a type of dataset by using machine-learning and the full power of the Gaia data. I will present a new approach in the form of a hybrid Convolutional Neural-Network (CNN) to derive atmospheric parameters (Teff, log(g), and [M/H]) and chemical abundances ([Fe/H] and [α/M]).

Our CNN is designed to effectively combine the Gaia DR3 RVS spectra, photometry (G, Bp, Rp), parallaxes, and XP coefficients and is able to extract additional information from non-spectral inputs to   supplement the limited spectral coverage of the RVS spectra. We manage to characterize the [α/M] − [M/H] bimodality from the inner regions to the outer part of the Milky Way, which has never been characterized using RVS spectra or similar datasets. I will also discuss the benefits of using CNNs for future  large scale spectroscopic surveys such as 4MOST.

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We look forward to seeing many of you there. Thanks!

Adur and Adélaïde

Upcoming Events:

2023-10-20 Adam Rains
2023-10-27 Maryam Saberi
2023-11-03 TBA
2023-11-10 Alberto Saldana Lopez
2023-11-17 TBA
2023-11-24 Aline Chu
2023-12-01 Heitor Ernandes
2023-12-08 Quentin Perceval Xavier Pognan

You can subscribe to the seminars calendar in: https://ttt.astro.su.se/ical/astro-seminars.ics

(Please note that calendar can be subject to updates)

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Join Zoom Meeting:
https://stockholmuniversity.zoom.us/s/61002076352
Meeting ID: 610 0207 6352
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