Bibcode
Martinez-Valpuesta, Inma; Gerhard, Ortwin
Bibliographical reference
The Astrophysical Journal Letters, Volume 734, Issue 1, article id. L20, 4 pp. (2011).
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6
2011
Citations
105
Refereed citations
94
Description
It has been known for sometime that the Milky Way is a barred disk
galaxy. More recently several studies inferred from star count
observations that the Galaxy must contain a separate, new, flat long bar
component, twisted relative to the barred bulge. Here we use a
simulation with a boxy bulge and bar to suggest that these observations
can be reproduced with a single structure. In this simulation, a stellar
bar evolved from the disk, and the boxy bulge originated from it through
secular evolution and the buckling instability. We calculate star count
distributions for this model at different longitudes and latitudes, in a
similar way as observers have done for resolved star counts. Good
agreement between the simulation and the observations can be achieved
for a suitable snapshot, even though the simulation has a single boxy
bulge and bar structure. In this model, part of the long bar signature
is due to a volume effect in the star counts, and another part is due to
choosing a snapshot in which the planar part of the boxy bulge and bar
has developed leading ends through interaction with the adjacent spiral
arm heads. We also provide predictions from this model for the
line-of-sight velocity distributions at the longitudes with the long bar
signature, for comparison with upcoming surveys.