Chronography of the milky way's halo system with field blue horizontal-branch stars

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dc.contributor.authorSantucci, Rafael M.
dc.contributor.authorBeers, Timothy C.
dc.contributor.authorPlacco, Vinicius M.
dc.contributor.authorCarollo, Daniela
dc.contributor.authorRossi, Silvia
dc.contributor.authorLee, Young Sun
dc.contributor.authorDenissenkov, Pavel
dc.contributor.authorTumlinson, Jason
dc.contributor.authorTissera, Patricia B.
dc.date.accessioned2023-02-15T14:23:44Z
dc.date.available2023-02-15T14:23:44Z
dc.date.issued2015-11
dc.descriptionIndexación: Scopuses
dc.description.abstractIn a pioneering effort, Preston et al. reported that the colors of blue horizontal-branch (BHB) stars in the halo of the Galaxy shift with distance, from regions near the Galactic center to about 12 kpc away, and interpreted this as a correlated variation in the ages of halo stars, from older to younger, spanning a range of a few Gyrs. We have applied this approach to a sample of some 4700 spectroscopically confirmed BHB stars selected from the Sloan Digital Sky Survey to produce the first "chronographic map" of the halo of the Galaxy. We demonstrate that the mean de-reddened g - r color, increases outward in the Galaxy from -0.22 to -0.08 (over a color window spanning [-0.3: 0.0]) from regions close to the Galactic center to ∼40 kpc, independent of the metallicity of the stars. Models of the expected shift in the color of the field BHB stars based on modern stellar evolutionary codes confirm that this color gradient can be associated with an age difference of roughly 2-2.5 Gyr, with the oldest stars concentrated in the central ∼15 kpc of the Galaxy. Within this central region, the age difference spans a mean color range of about 0.05 mag (∼0.8 Gyr). Furthermore, we show that chronographic maps can be used to identify individual substructures, such as the Sagittarius Stream, and overdensities in the direction of Virgo and Monoceros, based on the observed contrast in their mean BHB colors with respect to the foreground/background field population. © 2015. The American Astronomical Society. All rights reserved..es
dc.description.urihttps://iopscience-iop-org.recursosbiblioteca.unab.cl/article/10.1088/2041-8205/813/1/L16
dc.identifier.doi10.1088/2041-8205/813/1/L16
dc.identifier.issn2041-8205
dc.identifier.urihttps://repositorio.unab.cl/xmlui/handle/ria/46877
dc.language.isoenes
dc.publisherInstitute of Physics Publishinges
dc.rights.licenseAtribución 4.0 Internacional (CC BY 4.0)
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/deed.es
dc.subjectGalaxyes
dc.subjecthaloes
dc.subjectmethodses
dc.subjectobservationales
dc.subjectmethodses
dc.subjectstatisticales
dc.subjectstarses
dc.subjecthorizontal-branches
dc.titleChronography of the milky way's halo system with field blue horizontal-branch starses
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Astrophysical Journal Letters Volume 813, Issue 11 November 2015 Article number L16
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