The Galah Survey : Classification and Diagnostics with t-SNE Reduction of Spectral Information
(2017) In Astrophysical Journal, Supplement Series 228(2).- 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... (More)
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, Hμ/Hβ emission, Hμ/Hβ emission superimposed on absorption, Hμ/Hβ P-Cygni, Hμ/Hβ 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.
(Less)
- author
- publishing date
- 2017-02-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- binaries: general, catalogs, methods: data analysis, stars: activity, stars: peculiar, surveys
- in
- Astrophysical Journal, Supplement Series
- volume
- 228
- issue
- 2
- article number
- 24
- publisher
- IOP Publishing
- external identifiers
-
- scopus:85014831098
- ISSN
- 0067-0049
- DOI
- 10.3847/1538-4365/228/2/24
- language
- English
- LU publication?
- no
- id
- 9426575d-f5cb-44de-be03-05a40de1c87b
- date added to LUP
- 2019-05-30 00:04:00
- date last changed
- 2022-04-11 12:19:48
@article{9426575d-f5cb-44de-be03-05a40de1c87b,
abstract = {{<p>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, Hμ/Hβ emission, Hμ/Hβ emission superimposed on absorption, Hμ/Hβ P-Cygni, Hμ/Hβ 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.</p>}},
author = {{Traven, G. and Matijevič, G. and Zwitter, T. and Žerjal, M. and Kos, J. and Asplund, M. and Bland-Hawthorn, J. and Casey, A. R. and De Silva, G. and Freeman, K. and Lin, J. and Martell, S. L. and Schlesinger, K. J. and Sharma, S. and Simpson, J. D. and Zucker, D. B. and Anguiano, B. and Da Costa, G. and Duong, L. and Horner, J. and Hyde, E. A. and Kafle, P. R. and Munari, U. and Nataf, D. and Navin, C. A. and Reid, W. and Ting, Y. S.}},
issn = {{0067-0049}},
keywords = {{binaries: general; catalogs; methods: data analysis; stars: activity; stars: peculiar; surveys}},
language = {{eng}},
month = {{02}},
number = {{2}},
publisher = {{IOP Publishing}},
series = {{Astrophysical Journal, Supplement Series}},
title = {{The Galah Survey : Classification and Diagnostics with t-SNE Reduction of Spectral Information}},
url = {{http://dx.doi.org/10.3847/1538-4365/228/2/24}},
doi = {{10.3847/1538-4365/228/2/24}},
volume = {{228}},
year = {{2017}},
}