THE Gaia-ESO Survey : Metal-rich bananas in the bulge
(2016) In Astrophysical Journal Letters 824(2).- Abstract
We analyze the kinematics of ∼2000 giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region -10° ≲ l≲ 10° and -11° ≲ b ≲ -3°. We find distinct kinematic trends in the metal-rich ([M H] > 0) and metal-poor ([M H] <0) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy-peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal-rich stars also exhibit peaky features in their line of sight velocity histograms,... (More)
We analyze the kinematics of ∼2000 giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region -10° ≲ l≲ 10° and -11° ≲ b ≲ -3°. We find distinct kinematic trends in the metal-rich ([M H] > 0) and metal-poor ([M H] <0) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy-peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal-rich stars also exhibit peaky features in their line of sight velocity histograms, particularly along the minor axis of the bulge. We propose that these features are due to stars on resonant orbits supporting the boxy-peanut bulge. This conjecture is strengthened through the comparison of the minor axis data with the velocity histograms of resonant orbits generated in simulations of buckled bars. The "banana" or 2:1:2 orbits provide strongly bimodal histograms with narrow velocity peaks that resemble the Gaia-ESO metal-rich data.
(Less)
- author
- organization
- publishing date
- 2016-06-20
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- galaxies: general, galaxies: kinematics and dynamics, Galaxy: bulge
- in
- Astrophysical Journal Letters
- volume
- 824
- issue
- 2
- article number
- L29
- publisher
- IOP Publishing
- external identifiers
-
- wos:000378168200013
- scopus:84976444253
- ISSN
- 2041-8205
- DOI
- 10.3847/2041-8205/824/2/L29
- project
- Gaia-ESO Survey
- language
- English
- LU publication?
- yes
- id
- 9c568909-138e-4124-9f9c-00d413f2d720
- date added to LUP
- 2016-08-17 14:22:09
- date last changed
- 2024-09-20 21:25:39
@article{9c568909-138e-4124-9f9c-00d413f2d720, abstract = {{<p>We analyze the kinematics of ∼2000 giant stars in the direction of the Galactic bulge, extracted from the Gaia-ESO survey in the region -10° ≲ l≲ 10° and -11° ≲ b ≲ -3°. We find distinct kinematic trends in the metal-rich ([M H] > 0) and metal-poor ([M H] <0) stars in the data. The velocity dispersion of the metal-rich stars drops steeply with latitude, compared to a flat profile in the metal-poor stars, as has been seen previously. We argue that the metal-rich stars in this region are mostly on orbits that support the boxy-peanut shape of the bulge, which naturally explains the drop in their velocity dispersion profile with latitude. The metal-rich stars also exhibit peaky features in their line of sight velocity histograms, particularly along the minor axis of the bulge. We propose that these features are due to stars on resonant orbits supporting the boxy-peanut bulge. This conjecture is strengthened through the comparison of the minor axis data with the velocity histograms of resonant orbits generated in simulations of buckled bars. The "banana" or 2:1:2 orbits provide strongly bimodal histograms with narrow velocity peaks that resemble the Gaia-ESO metal-rich data.</p>}}, author = {{Williams, Angus A. and Evans, N. W. and Molloy, Matthew and Kordopatis, Georges and Smith, M. C. and Shen, J. and Gilmore, G. and Randich, S. and Bensby, T. and Francois, P. and Koposov, S. E. and Recio-Blanco, A. and Bayo, A. and Carraro, G. and Casey, A. and Costado, T. and Franciosini, E. and Hourihane, A. and Laverny, P. De and Lewis, J. and Lind, K. and Magrini, L. and Monaco, L. and Morbidelli, L. and Sacco, G. G. and Worley, C. and Zaggia, S. and Mikolaitis}}, issn = {{2041-8205}}, keywords = {{galaxies: general; galaxies: kinematics and dynamics; Galaxy: bulge}}, language = {{eng}}, month = {{06}}, number = {{2}}, publisher = {{IOP Publishing}}, series = {{Astrophysical Journal Letters}}, title = {{THE Gaia-ESO Survey : Metal-rich bananas in the bulge}}, url = {{http://dx.doi.org/10.3847/2041-8205/824/2/L29}}, doi = {{10.3847/2041-8205/824/2/L29}}, volume = {{824}}, year = {{2016}}, }