SMHASH: A new mid-infrared RR Lyrae distance determination for the Local Group dwarf spheroidal galaxy Sculptor

Alessia Garofalo, Victoria Scowcroft, Gisella Clementini, Kathryn V. Johnston, Judith G. Cohen, Wendy L. Freedman, Barry F. Madore, Steven R. Majewski, Andrew J. Monson, Jillian R. Neeley, Carl J. Grillmair, David Hendel, Nitya Kallivayalil, Massimo Marengo, Roeland van der Marel

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Abstract

We present a new distance estimation for the Milky Way dwarf spheroidal satellite Sculptor obtained from multi-epoch mid-infrared observations of RR Lyrae stars (RRLs). The 3.6 μm observations have been acquired with the Infrared Array Camera onboard the Spitzer Space Telescope as part of the SMHASH program. Mid-infrared light curves for 42 RRLs were obtained, from which we measured Sculptor's distance modulus to be μ = 19.60 ± 0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.09 mag), using the 3.6 μm empirical period-luminosity relations derived from the Galactic globular clusterM4, orμ=19.57±0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.11 mag) using empirical relations in the same passband recently derived from the Large Magellanic Cloud globular cluster Reticulum. Both these measurements are in good agreement with values presented in previous works with Sculptor RRLs in optical bands, and are also consistent with recent near-infrared RR Lyrae results. Best agreement with the literature is found for the lattermodulus which is equivalent to a distance of d = 82 ± 1 (statistical) ± 2 (photometric) kpc (with σsys = 4 kpc). Finally, using a subsample of RRLs with spectroscopic metallicities, we demonstrate that these distance estimates are not affected by metallicity effects.

Original languageEnglish
Pages (from-to)578-595
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume481
Issue number1
Early online date16 Aug 2018
DOIs
Publication statusPublished - 21 Nov 2018

Keywords

  • Galaxies: dwarf
  • Galaxies: individual (Sculptor)
  • Milky Way
  • Stars: distances
  • Stars: variables: RR Lyrae
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

SMHASH : A new mid-infrared RR Lyrae distance determination for the Local Group dwarf spheroidal galaxy Sculptor. / Garofalo, Alessia; Scowcroft, Victoria; Clementini, Gisella; Johnston, Kathryn V.; Cohen, Judith G.; Freedman, Wendy L.; Madore, Barry F.; Majewski, Steven R.; Monson, Andrew J.; Neeley, Jillian R.; Grillmair, Carl J.; Hendel, David; Kallivayalil, Nitya; Marengo, Massimo; van der Marel, Roeland.

In: Monthly Notices of the Royal Astronomical Society, Vol. 481, No. 1, 21.11.2018, p. 578-595.

Research output: Contribution to journalArticle

Garofalo, A, Scowcroft, V, Clementini, G, Johnston, KV, Cohen, JG, Freedman, WL, Madore, BF, Majewski, SR, Monson, AJ, Neeley, JR, Grillmair, CJ, Hendel, D, Kallivayalil, N, Marengo, M & van der Marel, R 2018, 'SMHASH: A new mid-infrared RR Lyrae distance determination for the Local Group dwarf spheroidal galaxy Sculptor', Monthly Notices of the Royal Astronomical Society, vol. 481, no. 1, pp. 578-595. https://doi.org/10.1093/mnras/sty2222
Garofalo, Alessia ; Scowcroft, Victoria ; Clementini, Gisella ; Johnston, Kathryn V. ; Cohen, Judith G. ; Freedman, Wendy L. ; Madore, Barry F. ; Majewski, Steven R. ; Monson, Andrew J. ; Neeley, Jillian R. ; Grillmair, Carl J. ; Hendel, David ; Kallivayalil, Nitya ; Marengo, Massimo ; van der Marel, Roeland. / SMHASH : A new mid-infrared RR Lyrae distance determination for the Local Group dwarf spheroidal galaxy Sculptor. In: Monthly Notices of the Royal Astronomical Society. 2018 ; Vol. 481, No. 1. pp. 578-595.
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abstract = "We present a new distance estimation for the Milky Way dwarf spheroidal satellite Sculptor obtained from multi-epoch mid-infrared observations of RR Lyrae stars (RRLs). The 3.6 μm observations have been acquired with the Infrared Array Camera onboard the Spitzer Space Telescope as part of the SMHASH program. Mid-infrared light curves for 42 RRLs were obtained, from which we measured Sculptor's distance modulus to be μ = 19.60 ± 0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.09 mag), using the 3.6 μm empirical period-luminosity relations derived from the Galactic globular clusterM4, orμ=19.57±0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.11 mag) using empirical relations in the same passband recently derived from the Large Magellanic Cloud globular cluster Reticulum. Both these measurements are in good agreement with values presented in previous works with Sculptor RRLs in optical bands, and are also consistent with recent near-infrared RR Lyrae results. Best agreement with the literature is found for the lattermodulus which is equivalent to a distance of d = 82 ± 1 (statistical) ± 2 (photometric) kpc (with σsys = 4 kpc). Finally, using a subsample of RRLs with spectroscopic metallicities, we demonstrate that these distance estimates are not affected by metallicity effects.",
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T2 - A new mid-infrared RR Lyrae distance determination for the Local Group dwarf spheroidal galaxy Sculptor

AU - Garofalo, Alessia

AU - Scowcroft, Victoria

AU - Clementini, Gisella

AU - Johnston, Kathryn V.

AU - Cohen, Judith G.

AU - Freedman, Wendy L.

AU - Madore, Barry F.

AU - Majewski, Steven R.

AU - Monson, Andrew J.

AU - Neeley, Jillian R.

AU - Grillmair, Carl J.

AU - Hendel, David

AU - Kallivayalil, Nitya

AU - Marengo, Massimo

AU - van der Marel, Roeland

PY - 2018/11/21

Y1 - 2018/11/21

N2 - We present a new distance estimation for the Milky Way dwarf spheroidal satellite Sculptor obtained from multi-epoch mid-infrared observations of RR Lyrae stars (RRLs). The 3.6 μm observations have been acquired with the Infrared Array Camera onboard the Spitzer Space Telescope as part of the SMHASH program. Mid-infrared light curves for 42 RRLs were obtained, from which we measured Sculptor's distance modulus to be μ = 19.60 ± 0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.09 mag), using the 3.6 μm empirical period-luminosity relations derived from the Galactic globular clusterM4, orμ=19.57±0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.11 mag) using empirical relations in the same passband recently derived from the Large Magellanic Cloud globular cluster Reticulum. Both these measurements are in good agreement with values presented in previous works with Sculptor RRLs in optical bands, and are also consistent with recent near-infrared RR Lyrae results. Best agreement with the literature is found for the lattermodulus which is equivalent to a distance of d = 82 ± 1 (statistical) ± 2 (photometric) kpc (with σsys = 4 kpc). Finally, using a subsample of RRLs with spectroscopic metallicities, we demonstrate that these distance estimates are not affected by metallicity effects.

AB - We present a new distance estimation for the Milky Way dwarf spheroidal satellite Sculptor obtained from multi-epoch mid-infrared observations of RR Lyrae stars (RRLs). The 3.6 μm observations have been acquired with the Infrared Array Camera onboard the Spitzer Space Telescope as part of the SMHASH program. Mid-infrared light curves for 42 RRLs were obtained, from which we measured Sculptor's distance modulus to be μ = 19.60 ± 0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.09 mag), using the 3.6 μm empirical period-luminosity relations derived from the Galactic globular clusterM4, orμ=19.57±0.02 (statistical) ± 0.04 (photometric) mag (with σsys = 0.11 mag) using empirical relations in the same passband recently derived from the Large Magellanic Cloud globular cluster Reticulum. Both these measurements are in good agreement with values presented in previous works with Sculptor RRLs in optical bands, and are also consistent with recent near-infrared RR Lyrae results. Best agreement with the literature is found for the lattermodulus which is equivalent to a distance of d = 82 ± 1 (statistical) ± 2 (photometric) kpc (with σsys = 4 kpc). Finally, using a subsample of RRLs with spectroscopic metallicities, we demonstrate that these distance estimates are not affected by metallicity effects.

KW - Galaxies: dwarf

KW - Galaxies: individual (Sculptor)

KW - Milky Way

KW - Stars: distances

KW - Stars: variables: RR Lyrae

KW - Techniques: photometric

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DO - 10.1093/mnras/sty2222

M3 - Article

AN - SCOPUS:85054098131

VL - 481

SP - 578

EP - 595

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

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