Serendipitous discovery of a thin stellar stream near the Galactic bulge in the Pan-STARRS1 3π Survey

Bernard, Edouard J.; Ferguson, Annette M. N.; Schlafly, Edward F.; Abbas, Mohamad; Bell, Eric F.; Deacon, N. R.; Martín, Nicolás F.; Rix, H. W.; Sesar, Branimir; Slater, Colin T.; Peñarrubia, Jorge; Wyse, Rosemary F. Ġ.; Burgett, W. S.; Chambers, K.; Draper, P. W.; Hodapp, Klaus W.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A.; Metcalfe, N.; Morgan, J. S.; Price, P. A.; Tonry, J.; Wainscoat, R. J.; Waters, C.

doi:10.1093/mnrasl/slu089

Cited by 60 publications

(44 citation statements)

References 43 publications

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“…However, further insight can be obtained from the known kinematics of the star (see Table 1) and about half of the candidate GCs with matching metallicity (D. Casetti 2 ). We proceed under the assumption that the progenitor cluster is still intact, while evidence has also been found in the inner halo for disrupted GCs (Bernard et al 2014).…”

Section: Discussionmentioning

confidence: 99%

TheGaia-ESO Survey: A globular cluster escapee in the Galactic halo

Lind

Koposov

Battistini

et al. 2015

A&A

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A small fraction of the halo field is made up of stars that share the light element (Z ≤ 13) anomalies characteristic of second generation globular cluster (GC) stars. The ejected stars shed light on the formation of the Galactic halo by tracing the dynamical history of the clusters, which are believed to have once been more massive. Some of these ejected stars are expected to show strong Al enhancement at the expense of shortage of Mg, but until now no such star has been found. We search for outliers in the Mg and Al abundances of the few hundreds of halo field stars observed in the first eighteen months of the Gaia-ESO public spectroscopic survey. One halo star at the base of the red giant branch, here referred to as 22593757-4648029 is found to have [Mg/Fe] = −0.36 ± 0.04 and [Al/Fe] = 0.99 ± 0.08, which is compatible with the most extreme ratios detected in GCs so far. We compare the orbit of 22593757-4648029 to GCs of similar metallicity and find it unlikely that this star has been tidally stripped with low ejection velocity from any of the clusters. However, both chemical and kinematic arguments render it plausible that the star has been ejected at high velocity from the anomalous GC ω Centauri within the last few billion years. We cannot rule out other progenitor GCs, because some may have disrupted fully, and the abundance and orbital data are inadequate for many of those that are still intact.

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Section: Discussionmentioning

confidence: 99%

TheGaia-ESO Survey: A globular cluster escapee in the Galactic halo

Lind

Koposov

Battistini

et al. 2015

A&A

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“…Recent surveys have discovered dynamically cold tidal debris of many disrupted stellar systems-likely globular clusters or low mass dwarf galaxies-in the inner tens of kiloparsecs of the Milky Way (Grillmair 2010(Grillmair , 2014Bonaca et al 2012;Bernard et al 2014;Koposov et al 2014;Martin et al 2014). These debris, arranged in thin streams of stars, are powerful probes for the structure of our own galaxy.…”

Section: Introductionmentioning

confidence: 99%

“…This effect has been invoked by Sesar et al (2016) to explain the puzzling orbit and length of the recently observed Ophiuchus stream (Bernard et al 2014;Sesar et al 2015). This suggests that spherical potentials are no longer suitable for modeling tidal streams.…”

Section: Introductionmentioning

confidence: 99%

Dispersal of Tidal Debris in a Milky-Way-Sized Dark Matter Halo

Ngan

Carlberg

Bozek

et al. 2016

ApJ

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We simulate the tidal disruption of a collisionless N-body globular star cluster in a total of 300 different orbits selected to have galactocentric radii between 10 and 30 kpc in four dark matter halos: (a) a spherical halo with no subhalos, (b) a spherical halo with subhalos, (c) a realistic halo with no subhalos, and (d) a realistic halo with subhalos. This allows us to isolate and study how the halo's (lack of) dynamical symmetry and substructures affect the dispersal of tidal debris. The realistic halos are constructed from the snapshot of the Via Lactea II simulation at redshift zero. We find that the overall halo's symmetry disperses tidal debris to make the streams fluffier, consistent with previous studies of tidal debris of dwarf galaxies in larger orbits than ours in this study. On the other hand, subhalos in realistic potentials can locally enhance the densities along streams, making streams denser than their counterparts in smooth potentials. We show that many long and thin streams can survive in a realistic and lumpy halo for a Hubble time. This suggests that upcoming stellar surveys will likely uncover more thin streams which may contain density gaps that have been shown to be promising probes for dark matter substructures.

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“…The recently found cold (velocity dispersion 1 v ⪅ s km s −1 ) Ophiuchus stream (Bernard et al 2014), presents a puzzle in this respect: its stellar population is old (∼12 Gyr), yet it is on an orbit with an orbital period P 350 Myr » and it is apparently only 1.6kpc long (Sesar et al 2015, hereafter S15). To maintain such a short length, the observed debris should have been disrupted only within the last 250 million years.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Fanning in the Ophiuchus Stream

Sesar

Price-Whelan

Cohen

et al. 2015

ApJL

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The Ophiuchus stellar stream presents a dynamical puzzle: its old stellar populations (∼12 Gyr) cannot be reconciled with (1) its orbit in a simple model for the Milky Way potential and (2) its short angular extent, both of which imply that the observed stream formed within the last 1 Gyr < . Recent theoretical work has shown that streams on chaotic orbits may abruptly fan out near their apparent ends; stars in these fans are dispersed in both position and velocity and may be difficult to associate with the stream. Here we present the first evidence of such stream-fanning in the Ophiuchus stream, traced by four blue horizontal branch stars beyond the apparent end of the stream. These stars stand out from the background by their high velocities (v 230 los > km s −1 ) against ∼40 other stars: their velocities are comparable to those of the stream, but would be exceptional if they were unrelated halo stars. Their positions and velocities are, however, inconsistent with simple extrapolation of the observed cold, high-density portion of the stream. These observations suggest that stream-fanning may be a real, observable effect and, therefore, that Ophiuchus may be on a chaotic orbit. They also show that the Ophiuchus stream is more extended and hence dynamically older than previously thought, easing the stellar population versus dynamical age tension.

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Serendipitous discovery of a thin stellar stream near the Galactic bulge in the Pan-STARRS1 3π Survey

Cited by 60 publications

References 43 publications

TheGaia-ESO Survey: A globular cluster escapee in the Galactic halo

TheGaia-ESO Survey: A globular cluster escapee in the Galactic halo

Dispersal of Tidal Debris in a Milky-Way-Sized Dark Matter Halo

Evidence of Fanning in the Ophiuchus Stream

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