Abstract
We identify a halo substructure in the Tycho Gaia Astrometric Solution
(TGAS) data set, cross-matched with the Radial Velocity Experiment
(RAVE-on) data release. After quality cuts, the stars with large radial
action (JR > 800 km s−1 kpc) are
extracted. A subset of these stars is clustered in longitude and
velocity and can be selected with further cuts. The 14 stars are centred
on (X, Y, Z) ≈ (9.0, −1.0, −0.6) kpc and form a coherently moving structure in the halo with median (vR, vϕ, vz) = (167.33, 0.86, −94.85) km s−1.
They are all metal-poor giants with median [Fe/H] = −0.83. To guard
against the effects of distance errors, we compute spectrophotometric
distances for 8 out of the 14 stars where this is possible. We find that
six of the stars are still comoving. These six stars also have a much
tighter [Fe/H] distribution ∼−0.7 with one exception ([Fe/H] = −2.12).
We conclude that the existence of the comoving cluster is stable against
changes in distance estimation and conjecture that this is the
dissolving remnant of a globular cluster accreted long ago.
Original language | English |
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Journal | Monthly Notices of the Royal Astronomical Society: Letters, Volume |
Early online date | 10 Apr 2017 |
DOIs | |
Publication status | Published - 1 Jul 2017 |
Keywords / Materials (for Non-textual outputs)
- astro-ph.GA
- astro-ph.CO