APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy

Journal Article · Sun Aug 20 00:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7DDC· OSTI ID:22663205

Hasselquist, Sten; Holtzman, Jon ^[1]; Shetrone, Matthew ^[2]; Smith, Verne; Nidever, David L. ^[3]; McWilliam, Andrew ^[4]; Fernández-Trincado, J. G.; Tang, Baitian ^[5]; Beers, Timothy C. ^[6]; Majewski, Steven R.; Anguiano, Borja ^[7]; Tissera, Patricia B. ^[8]; Alvar, Emma Fernández; Carigi, Leticia; Delgado Inglada, Gloria ^[9]; Allende Prieto, Carlos; Battaglia, Giuseppina; García-Hernández, D. A. ^[10]; Almeida, Andres ^[11]; Frinchaboy, Peter ^[12] ; others, and

---

1. New Mexico State University, Las Cruces, NM 88003 (United States)
2. University of Texas at Austin, McDonald Observatory, Fort Davis, TX 79734 (United States)
3. National Optical Astronomy Observatories, Tucson, AZ 85719 (United States)
4. The Observatories of the Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
5. Departamento de Astronomía, Casilla 160-C, Universidad de Concepción, Concepción (Chile)
6. Department of Physics and JINA Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, IN 46556 (United States)
7. Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
8. Department of Physics, Universidad Andres Bello, 700 Fernandez Concha (Chile)
9. Instituto de Astronomía, Universidad Nacional Autnoma de México, Apdo. Postal 70264, Ciudad de México, 04510 (Mexico)
10. Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)
11. Departamento de Física, Facultad de Ciencias, Universidad de La Serena, Cisternas 1200, La Serena (Chile)
12. Texas Christian University, Fort Worth, TX 76129 (United States)

The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze thechemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] ≳ −0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function.

• OSTI ID: 22663205
• Journal Information: Astrophysical Journal, Vol. 845, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ELEMENT ABUNDANCE
GALACTIC EVOLUTION
HYDROSTATICS
ISOCHRONOUS CYCLOTRONS
MAGELLANIC CLOUDS
MASS
MILKY WAY
RED GIANT STARS
RESOLUTION
VISIBLE RADIATION