Milky Way metallicity gradient from Gaia DR2 F/1O double-mode Cepheids

• Verfasst von: Lemasle, Bertrand [VerfasserIn]
• Verfasst von: Hajdu, Gergely [VerfasserIn]
• Verfasst von: Grebel, Eva K. [VerfasserIn]
• Titel: Milky Way metallicity gradient from Gaia DR2 F/1O double-mode Cepheids
• Verf.angabe: B. Lemasle, G. Hajdu, V. Kovtyukh, L. Inno, E.K. Grebel, M. Catelan, G. Bono, P. François, A. Kniazev, R. da Silva, and J. Storm
• Fussnoten: Gesehen am 21.02.2019
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Jahr Quelle: 2018
• Band/Heft Quelle: 618(2018) Artikel-Nummer A160, 10 Seiten
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/201834050
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1587863383

Abstract

<i>Context<i/>. The ratio of the first overtone (1O)/fundamental (F) periods of mixed-mode Cepheids that pulsate simultaneously in these two modes (F/1O) is metallicity-dependent. It can therefore be used to characterize the systems that host such variable stars.<i>Aims<i/>. We want to take advantage of the F/1O double-mode Cepheids listed in the <i>Gaia<i/> Data Release 2 (DR2) catalog to derive the metallicity gradient in the Milky Way disk.<i>Methods<i/>. The metallicity is derived from the ratio of the first overtone and fundamental periods provided by <i>Gaia<i/> DR2 while the <i>Gaia<i/> DR2 parallaxes are used to determine the Galactocentric distances of the stars.<i>Results<i/>. From a visual inspection of the light curves, it turns out that a large fraction (77%) of the Galactic F/1O double-mode Cepheids in <i>Gaia<i/> DR2 are spurious detections. <i>Gaia<i/> DR2 provides three new bona fide F/1O Cepheids. Combining them with the currently known F/1O Cepheids and using the <i>Gaia<i/> DR2 parallaxes for the entire sample, we can derive the metallicity gradient in the Milky Way disk. We find a slope of -0.045 ± 0.007 dex kpc<sup>−1<sup/> using a bootstrap method, and of -0.040 ± 0.002 dex kpc<sup>−1<sup/> using a total least squares method. These results are in good agreement with previous determinations of the [Fe/H] gradient in the disk based on canonical Cepheids.<i>Conclusions<i/>. The period ratio of F/1O Cepheids allows for a reliable determination of the metallicity gradient in the Milky Way, and in turn, in other systems that would be difficult to reach via classical spectroscopic methods.