The GALAH survey: characterization of emission-line stars with spectral modelling using autoencoders
Article
Article Title | The GALAH survey: characterization of emission-line stars with spectral modelling using autoencoders |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Cotar, Klemen (Author), Zwitter, Tomaz (Author), Traven, Gregor (Author), Bland-Hawthorn, Joss (Author), Buder, Sven (Author), Hayden, Michael R. (Author), Kos, Janez (Author), Lewis, Geraint F. (Author), Martell, Sarah L. (Author), Nordlander, Thomas (Author), Stello, Dennis (Author), Horner, Jonathan (Author), Ting, Yuan-Sen (Author), Zerjal, Marusa (Author) and Galah Collaboration, . (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 500 (4), pp. 4849-4865 |
Number of Pages | 17 |
Year | 2021 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/staa2524 |
Web Address (URL) | https://academic.oup.com/mnras/article/500/4/4849/6029994 |
Abstract | We present a neural network autoencoder structure that is able to extract essential latent spectral features from observed spectra and then reconstruct a spectrum from those features. Because of the training with a set of unpeculiar spectra, the network is able to reproduce a spectrum of high signal-to-noise ratio that does not show any spectral peculiarities, even if they are present in an observed spectrum. Spectra generated in this manner were used to identify various emission features among spectra acquired by multiple surveys using the HERMES spectrograph at the Anglo-Australian telescope. Emission features were identified by a direct comparison of the observed and generated spectra. Using the described comparison procedure, we discovered 10 364 candidate spectra with varying intensities (from partially filled-in to well above the continuum) of the Hα/Hβ emission component, produced by different physical mechanisms. A fraction of these spectra belong to the repeated observation that shows temporal variability in their emission profile. Among the emission spectra, we find objects that feature contributions from a nearby rarefied gas (identified through the emission of [N II] and [S II] lines) that was identified in 4004 spectra, which were not all identified as having Hα emission. The positions of identified emission-line objects coincide with multiple known regions that harbour young stars. Similarly, detected nebular emission spectra coincide with visually prominent nebular clouds observable in the red all-sky photographic composites. |
Keywords | line: profiles; methods: data analysis; catalogues; stars: activity; stars: emission line; Be; stars: peculiar; Astrophysics - Solar and; Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies; Astrophysics - Instrumentation and Methods for Astrophysics; Physics -; Data Analysis; Statistics and Probability |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Institution of Origin | University of Southern Queensland |
Byline Affiliations | University of Ljubljana, Slovenia |
Lund Observatory, Sweden | |
University of Sydney | |
Australian National University | |
University of New South Wales | |
University of New South Wales | |
Centre for Astrophysics | |
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions, Australia |
https://research.usq.edu.au/item/q612w/the-galah-survey-characterization-of-emission-line-stars-with-spectral-modelling-using-autoencoders
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