TRACING THE ORIGIN OF THE AQUARIUS STREAM. I

Journal Article · Fri Aug 10 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/755/1/35· OSTI ID:22039162

Wylie-de Boer, Elizabeth; Freeman, Kenneth; Keller, Stefan ^[1]; Williams, Mary; Steinmetz, Matthias ^[2]; Munari, Ulisse ^[3]

---

1. Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia)
2. Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
3. INAF Astronomical Observatory of Padova, 36012 Asiago (Italy)

We present an abundance analysis of six member stars of the recently discovered Aquarius stream, in an attempt to ascertain whether this halo stream is real and, if so, to understand its origin. The mean metallicities of the six stars have a dispersion of only 0.10 dex, indicating that they are part of a chemically coherent structure. We then investigate whether the stream represents the debris of a disrupted dwarf galaxy or a disrupted globular cluster. The [Ni/Fe]-[Na/Fe] plane provides a good diagnostic: globular cluster stars and dwarf spheroidal galaxy stars are well separated in this plane, and the Aquarius stream stars lie unambiguously in the globular cluster region. The Aquarius stream stars also lie on the distinct [Na/Fe]-[O/Fe] and [Mg/Fe]-[Al/Fe] relations delineated by Galactic globular cluster stars. Spectroscopic parameters for the six Aquarius stars show that they are tightly confined to a 12 Gyr, [Fe/H] =-1.0, {alpha}-enhanced isochrone, consistent with their identification as globular cluster debris. We present evidence that the Aquarius stream may continue through the disk and out into the northern halo. Our results indicate a globular cluster origin for the Aquarius stream and demonstrate the potential for chemical tagging to identify the origins of Galactic substructures.

• OSTI ID: 22039162
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 755; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ASTRONOMY
ASTROPHYSICS
DISPERSIONS
GALACTIC EVOLUTION
GALAXIES
STAR CLUSTERS
STARS