Whitten, D. D.; Placco, V. M.; Beers, T. C.; Chies-Santos, A. L.; Bonatto, C.; Varela, J.; Cristóbal-Hornillos, D.; Ederoclite, A.; Masseron, T.; Lee, Y. S.; Akras, S.; Borges Fernandes, M.; Caballero, J. A.; Cenarro, A. J.; Coelho, P.; Costa-Duarte, M. V.; Daflon, S.; Dupke, R. A.; Lopes de Oliveira, R.; López-Sanjuan, C.; Marín-Franch, A.; Mendes de Oliveira, C.; Moles, M.; Orsi, A. A.; Rossi, S.; Sodré, L.; Vázquez Ramió, H.
Bibliographical reference
Astronomy and Astrophysics, Volume 622, id.A182, 18 pp.
Description
Context. We present a new methodology for the estimation of stellar
atmospheric parameters from narrow- and intermediate-band photometry of
the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a
method for target pre-selection of low-metallicity stars for follow-up
spectroscopic studies. Photometric metallicity estimates for stars in
the globular cluster M15 are determined using this method. Aims:
By development of a neural-network-based photometry pipeline, we aim to
produce estimates of effective temperature, Teff, and
metallicity, [Fe/H], for a large subset of stars in the J-PLUS
footprint. Methods: The Stellar Photometric Index Network
Explorer, SPHINX, was developed to produce estimates of Teff
and [Fe/H], after training on a combination of J-PLUS photometric inputs
and synthetic magnitudes computed for medium-resolution (R 2000)
spectra of the Sloan Digital Sky Survey. This methodology was applied to
J-PLUS photometry of the globular cluster M15. Results: Effective
temperature estimates made with J-PLUS Early Data Release photometry
exhibit low scatter, σ(Teff) = 91 K, over the
temperature range 4500 < Teff (K) < 8500. For stars
from the J-PLUS First Data Release with 4500 < Teff (K)
< 6200, 85 ± 3% of stars known to have [Fe/H] < -2.0 are
recovered by SPHINX. A mean metallicity of [Fe/H] = - 2.32 ±
0.01, with a residual spread of 0.3 dex, is determined for M15 using
J-PLUS photometry of 664 likely cluster members. Conclusions: We
confirm the performance of SPHINX within the ranges specified, and
verify its utility as a stand-alone tool for photometric estimation of
effective temperature and metallicity, and for pre-selection of
metal-poor spectroscopic targets.
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