Bibcode
Hunt, J. A. S.; Bovy, Jo; Pérez-Villegas, Angeles; Holtzman, Jon A.; Sobeck, Jennifer; Chojnowski, Drew; Santana, Felipe A.; Palicio, P. A.; Wegg, Christopher; Gerhard, Ortwin; Almeida, Andrés; Bizyaev, Dmitry; Fernandez-Trincado, Jose G.; Lane, Richard R.; Longa-Peña, Penélope; Majewski, Steven R.; Pan, Kaike; Roman-Lopes, Alexandre
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 474, Issue 1, p.95-101
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2
2018
Citations
29
Refereed citations
27
Description
The Hercules stream is a group of comoving stars in the solar
neighbourhood, which can potentially be explained as a signature of
either the outer Lindblad resonance (OLR) of a fast Galactic bar or the
corotation resonance (CR) of a slower bar. In either case, the feature
should be present over a large area of the disc. With the recent
commissioning of the APOGEE-2 Southern spectrograph we can search for
the Hercules stream at (l, b) = (270°, 0), a direction in which the
Hercules stream, if caused by the bar's OLR, would be strong enough to
be detected using only the line-of-sight velocities. We clearly detect a
narrow, Hercules-like feature in the data that can be traced from the
solar neighbourhood to a distance of about 4 kpc. The detected feature
matches well the line-of-sight velocity distribution from the fast-bar
(OLR) model. Confronting the data with a model where the Hercules stream
is caused by the CR of a slower bar leads to a poorer match, as the
corotation model does not predict clearly separated modes, possibly
because the slow-bar model is too hot.