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The GALAH survey : Characterization of emission-line stars with spectral modelling using autoencoders

Čotar, Klemen ; Zwitter, Tomaz ; Traven, Gregor LU ; Bland-Hawthorn, Joss ; Buder, Sven ; Hayden, Michael R. ; Kos, Janez ; Lewis, Geraint F. ; Martell, Sarah L. LU and Nordlander, Thomas , et al. (2021) In Monthly Notices of the Royal Astronomical Society 500(4). p.4849-4865
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... (More)

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.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
catalogues, line: profiles, methods: data analysis, stars: activity, stars: emission line, Be, stars: peculiar
in
Monthly Notices of the Royal Astronomical Society
volume
500
issue
4
pages
17 pages
publisher
Oxford University Press
external identifiers
  • scopus:85099700962
ISSN
0035-8711
DOI
10.1093/mnras/staa2524
language
English
LU publication?
yes
id
3754a6cb-e014-474f-8172-5cfc9f7baff2
date added to LUP
2021-02-02 08:44:51
date last changed
2023-01-01 03:59:45
@article{3754a6cb-e014-474f-8172-5cfc9f7baff2,
  abstract     = {{<p>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. </p>}},
  author       = {{Čotar, Klemen and Zwitter, Tomaz and Traven, Gregor and Bland-Hawthorn, Joss and Buder, Sven and Hayden, Michael R. and Kos, Janez and Lewis, Geraint F. and Martell, Sarah L. and Nordlander, Thomas and Stello, Dennis and Horner, Jonathan and Ting, Yuan Sen and Zerjal, Maruša}},
  issn         = {{0035-8711}},
  keywords     = {{catalogues; line: profiles; methods: data analysis; stars: activity; stars: emission line, Be; stars: peculiar}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{4849--4865}},
  publisher    = {{Oxford University Press}},
  series       = {{Monthly Notices of the Royal Astronomical Society}},
  title        = {{The GALAH survey : Characterization of emission-line stars with spectral modelling using autoencoders}},
  url          = {{http://dx.doi.org/10.1093/mnras/staa2524}},
  doi          = {{10.1093/mnras/staa2524}},
  volume       = {{500}},
  year         = {{2021}},
}