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A New Faint Milky Way Satellite Discovered in the Pan-STARRS1 3π Survey

Laevens, B.P.M.; Martin, N.F.; Ibata, R.A.; Rix, H.-W.; Bernard, E.J.; Bell, E.F.; Sesar, B.; Ferguson, A.M.N.; Schlafly, E.F.; Slater, C.T.; Burgett, W.S.; Chambers, K.C.; Flewelling, H.; Hodapp, K.A.; Kaiser, N.; Kudritzki, R.-P.; Lupton, R.H.; Magnier, E.A.; Metcalfe, N.; Morgan, J.S.; Price, P.A.; Tonry, J.L.; Wainscoat, R.J.; Waters, C.

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B.P.M. Laevens

N.F. Martin

R.A. Ibata

H.-W. Rix

E.J. Bernard

E.F. Bell

B. Sesar

A.M.N. Ferguson

E.F. Schlafly

C.T. Slater

W.S. Burgett

K.C. Chambers

H. Flewelling

K.A. Hodapp

N. Kaiser

R.-P. Kudritzki

R.H. Lupton

E.A. Magnier

J.S. Morgan

P.A. Price

J.L. Tonry

R.J. Wainscoat

C. Waters


We present the discovery of a faint Milky Way satellite, Laevens 2/Triangulum II, found in the Panoramic Survey Telescope And Rapid Response System (Pan-STARRS 1) 3 pi imaging data and confirmed with follow-up wide-field photometry from the Large Binocular Cameras. The stellar system, with an absolute magnitude of M_V=-1.8 +/-0.5, a heliocentric distance of 30 +2/-2 kpc, and a half-mass radius of 34 +9/-8 pc, shows remarkable similarity to faint, nearby, small satellites such as Willman 1, Segue 1, Segue 2, and Bo\"otes II. The discovery of Laevens 2/Triangulum II further populates the region of parameter space for which the boundary between dwarf galaxies and globular clusters becomes tenuous. Follow-up spectroscopy will ultimately determine the nature of this new satellite, whose spatial location hints at a possible connection with the complex Triangulum-Andromeda stellar structures.


Laevens, B., Martin, N., Ibata, R., Rix, H., Bernard, E., Bell, E., …Waters, C. (2015). A New Faint Milky Way Satellite Discovered in the Pan-STARRS1 3π Survey. Astrophysical Journal Letters, 802(2),

Journal Article Type Article
Acceptance Date Mar 17, 2015
Publication Date Apr 1, 2015
Deposit Date Aug 3, 2015
Publicly Available Date Sep 3, 2015
Journal Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 802
Issue 2
Keywords Galaxies: dwarf, Galaxy: structure, Globular clusters: general, Local Group.


Published Journal Article (429 Kb)

Copyright Statement
© 2015. The American Astronomical Society. All rights reserved.

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