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RR Lyrae Stars in the Field of Sagittarius II

Joo, Seok-Joo; Kyeong, Jaemann; Yang, Soung-Chul; Han, Sang-Il; Sung, Eon-Chang; Rey, Soo-Chang; Jerjen, Helmut; Kim, Hak-Sub; Kim, Dongwon; Jeong, Hyunjin; Ree, Chang H.

Description

We present the detection of RR Lyrae variable stars in the field of the Sagittarius. II (Sgr II) ultra-faint dwarf (UFD) galaxy. Using B, V time-series photometry obtained with the Korea Microlensing Telescope Network (KMTNet) 1.6 m telescope at CTIO and G-band data from Gaia Data Release 2 (DR2), we identified and characterized two ab-type and four c-type RR Lyrae variables. Five out of the six stars are clustered within three half-light radii (similar to 4'.8) of the galaxy indicating their...[Show more]

dc.contributor.authorJoo, Seok-Joo
dc.contributor.authorKyeong, Jaemann
dc.contributor.authorYang, Soung-Chul
dc.contributor.authorHan, Sang-Il
dc.contributor.authorSung, Eon-Chang
dc.contributor.authorRey, Soo-Chang
dc.contributor.authorJerjen, Helmut
dc.contributor.authorKim, Hak-Sub
dc.contributor.authorKim, Dongwon
dc.contributor.authorJeong, Hyunjin
dc.contributor.authorRee, Chang H.
dc.date.accessioned2021-04-29T23:27:09Z
dc.date.available2021-04-29T23:27:09Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/231142
dc.description.abstractWe present the detection of RR Lyrae variable stars in the field of the Sagittarius. II (Sgr II) ultra-faint dwarf (UFD) galaxy. Using B, V time-series photometry obtained with the Korea Microlensing Telescope Network (KMTNet) 1.6 m telescope at CTIO and G-band data from Gaia Data Release 2 (DR2), we identified and characterized two ab-type and four c-type RR Lyrae variables. Five out of the six stars are clustered within three half-light radii (similar to 4'.8) of the galaxy indicating their association with Sgr. II, while the RRab star V4 is located similar to 22' from the galaxy center. By excluding V4, the high c-type fraction (0.8) and the period of the only RRab star V3 (P-V3 similar or equal to 0.666 days) suggest an Oosterhoff. II (Oo II) classification for Sgr. II. Located close to the locus of Oo. II clusters in the period-amplitude diagram, V3 is similar to RRab stars in other UFDs having Oosterh off-intermediate and Oo. II properties. Sgr. II is, however, more compact than usual UFDs, placed in between star clusters and dwarf galaxies in the size-luminosity plane, and therefore spectroscopic studies are eventually required to ascertain the true nature of this stellar system. We derive the metallicity ([Fe/H] RRab similar or equal to -2.1 +/- 0.3) and heliocentric distance (similar to 64 +/- 3 kpc) of Sgr. II from the RR Lyrae stars, and estimate its age (similar to 12 Gyr) based on our stellar population models. The Oosterhoff properties of UFDs can be explained with the evolution effect of RR Lyrae stars in the instability strip.
dc.description.sponsorshipFunding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. S.C.R was partially supported by the Basic Science Research Program through the NRF of Korea funded by the Ministry of Education (2018R1A2B2006445). Support for this work was also provided by the NRF to the Center for Galaxy Evolution Research (2017R1A5A1070354). H. Jerjen acknowledges the support of the Australian Research Council through Discovery Project DP150100862. H. Jeong acknowledges support from the Basic Science Research Program through the National Research Foundation (NRF) of Korea, funded by the Ministry of Education (NRF2013R1A6A3A04064993). This research was made possible through the use of the APASS, funded by the Robert Martin Ayers Sciences Fund.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherIOP Publishing
dc.rights© 2019 The American Astronomical Society
dc.sourceThe Astrophysical Journal
dc.titleRR Lyrae Stars in the Field of Sagittarius II
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume875
dcterms.dateAccepted2019-03-19
dc.date.issued2019-04-23
local.identifier.absfor020103 - Cosmology and Extragalactic Astronomy
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.ariespublicationu3102795xPUB2025
local.publisher.urlhttps://iopscience.iop.org/
local.type.statusAccepted Version
local.contributor.affiliationJoo, Seok-Joo, Korea Astronomy and Space Science Institute
local.contributor.affiliationKyeong, Jaemann, Korea Astronomy and Space Science Institute
local.contributor.affiliationYang, Soung-Chul, Korea Astronomy and Space Science Institute
local.contributor.affiliationHan, Sang-Il, Korea Astronomy and Space Science Institute
local.contributor.affiliationSung, Eon-Chang, Korea Astronomy and Space Science Institute
local.contributor.affiliationRey, Soo-Chang, Chungnam National University
local.contributor.affiliationJerjen, Helmut, College of Science, ANU
local.contributor.affiliationKim, Hak-Sub, Korea Astronomy and Space Science Institute
local.contributor.affiliationKim, Dongwon, University of California
local.contributor.affiliationJeong, Hyunjin, Korea Astronomy and Space Science Institute
local.contributor.affiliationRee, Chang H., Korea Astronomy and Space Science Institute
dc.relationhttp://purl.org/au-research/grants/arc/DP150100862
local.bibliographicCitation.issue120
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage7
local.identifier.doi10.3847/1538-4357/ab11ca
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2020-12-27T07:23:52Z
local.identifier.scopusID2-s2.0-85067201565
local.identifier.thomsonID4.65642E+11
dcterms.accessRightsOpen Access
dc.provenancehttps://v2.sherpa.ac.uk/id/publication/6401..."Author accepted manuscript can be made open access on institutional repository after 12 month embargo" from SHERPA/RoMEO site (as at 30.4.2021)
CollectionsANU Research Publications

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