Journal article
The Galah Survey: Classification and Diagnostics with t-SNE Reduction of Spectral Information
The Astrophysical journal. Supplement series, Vol.228(2), pp.24-24
02/01/2017
DOI: 10.3847/1538-4365/228/2/24
Abstract
Galah is an ongoing high-resolution spectroscopic survey with the goal of disentangling the formation history of the Milky Way using the fossil remnants of disrupted star formation sites that are now dispersed around the Galaxy. It is targeting a randomly selected magnitude-limited (V <= 14) sample of stars, with the goal of observing one million objects. To date, 300,000 spectra have been obtained. Not all of them are correctly processed by parameter estimation pipelines, and we need to know about them. We present a semi-automated classification scheme that identifies different types of peculiar spectral morphologies in an effort to discover and flag potentially problematic spectra and thus help to preserve the integrity of the survey results. To this end, we employ the recently developed dimensionality reduction technique t-SNE (t-distributed stochastic neighbor embedding), which enables us to represent the complex spectral morphology in a two-dimensional projection map while still preserving the properties of the local neighborhoods of spectra. We find that the majority (178,483) of the 209,533 Galah spectra considered in this study represents normal single stars, whereas 31,050 peculiar and problematic spectra with very diverse spectral features pertaining to 28,579 stars are distributed into 10 classification categories: hot stars, cool metal-poor giants, molecular absorption bands, binary stars, H alpha/H beta emission, H alpha/H beta emission superimposed on absorption, H alpha/H beta P-Cygni, H alpha/H beta inverted P-Cygni, lithium absorption, and problematic. Classified spectra with supplementary information are presented in the catalog, indicating candidates for follow-up observations and population studies of the short-lived phases of stellar evolution.
Details
- Title: Subtitle
- The Galah Survey: Classification and Diagnostics with t-SNE Reduction of Spectral Information
- Creators
- G. Traven - University of LjubljanaG. Matijevic - Leibniz Institute for Astrophysics PotsdamT. Zwitter - University of LjubljanaM. Zerjal - University of LjubljanaJ. Kos - University of SydneyM. Asplund - Australian National UniversityJ. Bland-Hawthorn - University of SydneyA. R. Casey - University of CambridgeG. De Silva - Australian Astronomical ObservatoryK. Freeman - Australian National UniversityJ. Lin - Australian National UniversityS. L. Martell - UNSW SydneyK. J. Schlesinger - Mount Stromlo ObservatoryS. Sharma - University of SydneyJ. D. Simpson - Australian Astronomical ObservatoryD. B. Zucker - Macquarie UniversityB. Anguiano - Macquarie UniversityG. Da Costa - Australian National UniversityL. Duong - Australian National UniversityJ. Horner - University of Southern QueenslandE. A. Hyde - Australian Astronomical ObservatoryP. R. Kafle - University of Western AustraliaU. Munari - National Institute for AstrophysicsD. Nataf - Australian National UniversityC. A. Navin - Macquarie UniversityW. Reid - Western Sydney UniversityY. -S. Ting - Center for Astrophysics Harvard & Smithsonian
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal. Supplement series, Vol.228(2), pp.24-24
- Publisher
- IOP Publishing Ltd
- DOI
- 10.3847/1538-4365/228/2/24
- ISSN
- 0067-0049
- eISSN
- 1538-4365
- Number of pages
- 19
- Grant note
- ST/P00556X/1 / STFC; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) ST/P00556X/1 / Science and Technology Facilities Council; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC) P1-0188 / Slovenian Research Agency; Slovenian Research Agency - Slovenia 2013B/13; 2014A/25; 2015A/19 / Australian Astronomical Observatory DE140100598 / Australian Research Council
- Language
- English
- Date published
- 02/01/2017
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701735502771
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