Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way

Victoria Bonidie; Travis Court; Christine Mazzola Daher; Catherine E. Fielder; Carles Badenes; Jeffrey Newman; Maxwell Moe; Kaitlin M. Kratter; Matthew G. Walker; Steven R. Majewski; Christian R. Hayes; Sten Hasselquist; Keivan Stassun; Marina Kounkel; Don Dixon; Guy S. Stringfellow; Joleen K. Carlberg; Borja Anguiano; Nathan De Lee; Nicholas W. Troup

doi:10.3847/2041-8213/ac79af

Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way

Victoria Bonidie, Travis Court, Christine Mazzola Daher, Catherine E. Fielder, Carles Badenes, Jeffrey Newman, Maxwell Moe, Kaitlin M. Kratter, Matthew G. Walker, Steven R. Majewski, Christian R. Hayes, Sten Hasselquist, Keivan Stassun, Marina Kounkel, Don Dixon, Guy S. Stringfellow, Joleen K. Carlberg, Borja Anguiano, Nathan De Lee, Nicholas W. Troup

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Abstract

We use time-resolved spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to examine the distribution of radial velocity (RV) variations in 249 stars identified as members of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy by Hayes et al. We select Milky Way (MW) stars that have stellar parameters ( log(g), T eff, and [Fe/H] ) similar to those of the Sagittarius members by means of a k-d tree of dimension 3. We find that the shape of the distribution of RV shifts in Sgr dSph stars is similar to that measured in their MW analogs, but the total fraction of RV variable stars in the Sgr dSph is larger by a factor of 1/42. After ruling out other explanations for this difference, we conclude that the fraction of close binaries in the Sgr dSph is intrinsically higher than in the MW. We discuss the implications of this result for the physical processes leading to the formation of close binaries in dwarf spheroidal and spiral galaxies.

Original language	English (US)
Article number	L18
Journal	Astrophysical Journal Letters
Volume	933
Issue number	1
DOIs	https://doi.org/10.3847/2041-8213/ac79af
State	Published - Jul 1 2022

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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Bonidie, V., Court, T., Daher, C. M., Fielder, C. E., Badenes, C., Newman, J., Moe, M., Kratter, K. M., Walker, M. G., Majewski, S. R., Hayes, C. R., Hasselquist, S., Stassun, K., Kounkel, M., Dixon, D., Stringfellow, G. S., Carlberg, J. K., Anguiano, B., De Lee, N., & Troup, N. W. (2022). Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way. Astrophysical Journal Letters, 933(1), Article L18. https://doi.org/10.3847/2041-8213/ac79af

Bonidie, V, Court, T, Daher, CM, Fielder, CE, Badenes, C, Newman, J, Moe, M, Kratter, KM, Walker, MG, Majewski, SR, Hayes, CR, Hasselquist, S, Stassun, K, Kounkel, M, Dixon, D, Stringfellow, GS, Carlberg, JK, Anguiano, B, De Lee, N & Troup, NW 2022, 'Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way', Astrophysical Journal Letters, vol. 933, no. 1, L18. https://doi.org/10.3847/2041-8213/ac79af

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title = "Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way",

abstract = "We use time-resolved spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to examine the distribution of radial velocity (RV) variations in 249 stars identified as members of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy by Hayes et al. We select Milky Way (MW) stars that have stellar parameters ( log(g), T eff, and [Fe/H] ) similar to those of the Sagittarius members by means of a k-d tree of dimension 3. We find that the shape of the distribution of RV shifts in Sgr dSph stars is similar to that measured in their MW analogs, but the total fraction of RV variable stars in the Sgr dSph is larger by a factor of 1/42. After ruling out other explanations for this difference, we conclude that the fraction of close binaries in the Sgr dSph is intrinsically higher than in the MW. We discuss the implications of this result for the physical processes leading to the formation of close binaries in dwarf spheroidal and spiral galaxies.",

author = "Victoria Bonidie and Travis Court and Daher, {Christine Mazzola} and Fielder, {Catherine E.} and Carles Badenes and Jeffrey Newman and Maxwell Moe and Kratter, {Kaitlin M.} and Walker, {Matthew G.} and Majewski, {Steven R.} and Hayes, {Christian R.} and Sten Hasselquist and Keivan Stassun and Marina Kounkel and Don Dixon and Stringfellow, {Guy S.} and Carlberg, {Joleen K.} and Borja Anguiano and {De Lee}, Nathan and Troup, {Nicholas W.}",

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AU - Bonidie, Victoria

AU - Court, Travis

AU - Daher, Christine Mazzola

AU - Fielder, Catherine E.

AU - Badenes, Carles

AU - Newman, Jeffrey

AU - Moe, Maxwell

AU - Kratter, Kaitlin M.

AU - Walker, Matthew G.

AU - Majewski, Steven R.

AU - Hayes, Christian R.

AU - Hasselquist, Sten

AU - Stassun, Keivan

AU - Kounkel, Marina

AU - Dixon, Don

AU - Stringfellow, Guy S.

AU - Carlberg, Joleen K.

AU - Anguiano, Borja

AU - De Lee, Nathan

AU - Troup, Nicholas W.

PY - 2022/7/1

Y1 - 2022/7/1

N2 - We use time-resolved spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to examine the distribution of radial velocity (RV) variations in 249 stars identified as members of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy by Hayes et al. We select Milky Way (MW) stars that have stellar parameters ( log(g), T eff, and [Fe/H] ) similar to those of the Sagittarius members by means of a k-d tree of dimension 3. We find that the shape of the distribution of RV shifts in Sgr dSph stars is similar to that measured in their MW analogs, but the total fraction of RV variable stars in the Sgr dSph is larger by a factor of 1/42. After ruling out other explanations for this difference, we conclude that the fraction of close binaries in the Sgr dSph is intrinsically higher than in the MW. We discuss the implications of this result for the physical processes leading to the formation of close binaries in dwarf spheroidal and spiral galaxies.

AB - We use time-resolved spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to examine the distribution of radial velocity (RV) variations in 249 stars identified as members of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy by Hayes et al. We select Milky Way (MW) stars that have stellar parameters ( log(g), T eff, and [Fe/H] ) similar to those of the Sagittarius members by means of a k-d tree of dimension 3. We find that the shape of the distribution of RV shifts in Sgr dSph stars is similar to that measured in their MW analogs, but the total fraction of RV variable stars in the Sgr dSph is larger by a factor of 1/42. After ruling out other explanations for this difference, we conclude that the fraction of close binaries in the Sgr dSph is intrinsically higher than in the MW. We discuss the implications of this result for the physical processes leading to the formation of close binaries in dwarf spheroidal and spiral galaxies.

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Multiplicity Statistics of Stars in the Sagittarius Dwarf Spheroidal Galaxy: Comparison to the Milky Way

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