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The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs

Zhang, Z.; Liu, M.C.; Best, W.M.J.; Magnier, E.A.; Aller, K.M.; Chambers, K.C.; Draper, P.W.; Flewelling, H.; Hodapp, K.W.; Kaiser, N.; R.-p., Kudritzki; Metcalfe, N.; Wainscoat, R.J.; Waters, C.

The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs Thumbnail


Authors

Z. Zhang

M.C. Liu

W.M.J. Best

E.A. Magnier

K.M. Aller

K.C. Chambers

P.W. Draper

H. Flewelling

K.W. Hodapp

N. Kaiser

Kudritzki R.-p.

R.J. Wainscoat

C. Waters



Abstract

We are conducting a proper-motion survey for young brown dwarfs in the Taurus-Auriga molecular cloud based on the Pan-STARRS1 3π Survey. Our search uses multi-band photometry and astrometry to select candidates, and is wider (370 deg2) and deeper (down to ≈3 M Jup) than previous searches. We present here our search methods and spectroscopic follow-up of our high-priority candidates. Since extinction complicates spectral classification, we have developed a new approach using low-resolution (R ≈ 100) near-infrared spectra to quantify reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (lesssim100–3 M Jup in Taurus). We have discovered 25 low-gravity (vl-g) and the first 11 intermediate-gravity (int-g) substellar (M6–L1) members of Taurus, constituting the largest single increase of Taurus brown dwarfs to date. We have also discovered 1 new Pleiades member and 13 new members of the Perseus OB2 association, including a candidate very wide separation (58 kau) binary. We homogeneously reclassify the spectral types and extinctions of all previously known Taurus brown dwarfs. Altogether our discoveries have thus far increased the substellar census in Taurus by ≈40% and added three more L-type members (lesssim5–10 M Jup). Most notably, our discoveries reveal an older (>10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. The mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes.

Citation

Zhang, Z., Liu, M., Best, W., Magnier, E., Aller, K., Chambers, K., …Waters, C. (2018). The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs. Astrophysical Journal, 858(1), Article 41. https://doi.org/10.3847/1538-4357/aab269

Journal Article Type Article
Acceptance Date Feb 20, 2018
Online Publication Date May 3, 2018
Publication Date May 3, 2018
Deposit Date May 16, 2018
Publicly Available Date May 16, 2018
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 858
Issue 1
Article Number 41
DOI https://doi.org/10.3847/1538-4357/aab269

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© 2018. The American Astronomical Society. All rights reserved.







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