The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds
Name:
Nidever_2020_ApJ_895_88.pdf
Size:
4.525Mb
Format:
PDF
Description:
Final Published Version
Author
Nidever, David L.Hasselquist, Sten
Hayes, Christian R.
Hawkins, Keith
Povick, Joshua
Majewski, Steven R.
Smith, Verne V.
Anguiano, Borja
Stringfellow, Guy S.
Sobeck, Jennifer S.
Cunha, Katia
Beers, Timothy C.

Bestenlehner, Joachim M.
Cohen, Roger E.
Garcia-Hernandez, D. A.
Jönsson, Henrik
Nitschelm, Christian
Shetrone, Matthew
Lacerna, Ivan

Allende Prieto, Carlos
Beaton, Rachael L.
Dell’Agli, Flavia
Fernández-Trincado, José G.
Feuillet, Diane

Gallart, Carme

Hearty, Fred R.
Holtzman, Jon
Manchado, Arturo

Muñoz, Ricardo R.
O’Connell, Robert
Rosado, Margarita
Affiliation
Univ Arizona, Steward ObservIssue Date
2020-05-28
Metadata
Show full item recordPublisher
IOP PUBLISHING LTDCitation
Nidever, D. L., Hasselquist, S., Hayes, C. R., Hawkins, K., Povick, J., Majewski, S. R., ... & Rosado, M. (2020). The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds. The Astrophysical Journal, 895(2), 88.Journal
ASTROPHYSICAL JOURNALRights
© 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We report the first APOGEE metallicities and alpha-element abundances measured for 3600 red giant stars spanning a large radial range of both the Large (LMC) and Small Magellanic Clouds, the largest Milky Way (MW) dwarf galaxies. Our sample is an order of magnitude larger than that of previous studies and extends to much larger radial distances. These are the first results presented that make use of the newly installed southern APOGEE instrument on the du Pont telescope at Las Campanas Observatory. Our unbiased sample of the LMC spans a large range in metallicity, from [Fe/H] = -0.2 to very metal-poor stars with [Fe/H] -2.5, the most metal-poor Magellanic Cloud (MC) stars detected to date. The LMC [alpha/Fe]-[Fe/H] distribution is very flat over a large metallicity range but rises by similar to 0.1 dex at -1.0 < [Fe/H] less than or similar to -0.5. We interpret this as a sign of the known recent increase in MC star formation activity and are able to reproduce the pattern with a chemical evolution model that includes a recent "starburst." At the metal-poor end, we capture the increase of [alpha/Fe] with decreasing [Fe/H] and constrain the "alpha-knee" to [Fe/H] less than or similar to -2.2 in both MCs, implying a low star formation efficiency of similar to 0.01 Gyr(-1). The MC knees are more metal-poor than those of less massive MW dwarf galaxies such as Fornax, Sculptor, or Sagittarius. One possible interpretation is that the MCs formed in a lower-density environment than the MW, a hypothesis that is consistent with the paradigm that the MCs fell into the MW's gravitational potential only recently.ISSN
0004-637XEISSN
1538-4357Version
Final published versionSponsors
European Regional Development Fundae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/ab7305