Details

Autor(en) / Beteiligte

• Sesar, Branimir
• Bovy, Jo
• Bernard, Edouard J.
• Caldwell, Nelson
• Cohen, Judith G.
• Fouesneau, Morgan
• Johnson, Christian I.
• Ness, Melissa
• Ferguson, Annette M. N.
• Martin, Nicolas F.
• Price-Whelan, Adrian M.
• Rix, Hans-Walter
• Schlafly, Edward F.
• Burgett, William S.
• Chambers, Kenneth C.
• Flewelling, Heather
• Hodapp, Klaus W.
• Kaiser, Nick
• Magnier, Eugene A.
• Platais, Imants
• Tonry, John L.
• Waters, Christopher
• Wyse, Rosemary F. G.

Titel

THE NATURE AND ORBIT OF THE OPHIUCHUS STREAM

Ist Teil von

• The Astrophysical journal, 2015-08, Vol.809 (1), p.1-16

Ort / Verlag

United Kingdom: The American Astronomical Society

Erscheinungsjahr

2015

Quelle

Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals

Beschreibungen/Notizen

• ABSTRACT The Ophiuchus stream is a recently discovered stellar tidal stream in the Milky Way. We present high-quality spectroscopic data for 14 stream member stars obtained using the Keck and MMT telescopes. We confirm the stream as a fast moving (vlos ∼ 290 km s−1), kinematically cold group ( km s−1) of -enhanced and metal-poor stars ([ /Fe] ∼ 0.4 dex, [Fe/H] ∼ −2.0 dex). Using a probabilistic technique, we model the stream simultaneously in line-of-sight velocity, color-magnitude, coordinate, and proper motion space, and so determine its distribution in 6D phase-space. We find that the stream extends in distance from 7.5 to 9 kpc from the Sun; it is 50 times longer than wide, merely appearing highly foreshortened in projection. The analysis of the stellar population contained in the stream suggests that it is ∼12 Gyr old, and that its initial stellar mass was ∼2 × 104 M (or at least 7 × 103 M ). Assuming a fiducial Milky Way potential, we fit an orbit to the stream that matches the observed phase-space distribution, except for some tension in the proper motions: the stream has an orbital period of ∼350 Myr, and is on a fairly eccentric orbit (e ∼ 0.66) with a pericenter of ∼3.5 kpc and an apocenter of ∼17 kpc. The phase-space structure and stellar population of the stream show that its progenitor must have been a globular cluster that was disrupted only ∼240 Myr ago. We do not detect any significant overdensity of stars along the stream that would indicate the presence of a progenitor, and conclude that the stream is all that is left of the progenitor.