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Durham University

Department of Physics

Staff profile

Publication details for Dr Nigel Metcalfe

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. (2015). A New Faint Milky Way Satellite Discovered in the Pan-STARRS1 3π Survey. The Astrophysical Journal 802(2): L18.

Author(s) from Durham


We present the discovery of a faint Milky Way satellite, Laevens 2/Triangulum II, found in the Panoramic Survey Telescope And Rapid Response System 3π imaging data and confirmed with follow-up wide-field photometry from the Large Binocular Cameras. The stellar system, with an absolute magnitude of MV = −1.8 ± 0.5, a heliocentric distance of $30_{-2}^{+2}\;{\rm kpc}$, and a half-mass–radius of $34_{-8}^{+9}\;{\rm pc}$, shows remarkable similarity to faint, nearby, small satellites such as Willman 1, Segue 1, Segue 2, and Boötes 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.