Milky Way metallicity gradient from Gaia DR2 F/1O double-mode Cepheids
<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/>....
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| Main Authors: | , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
26 October 2018
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| In: |
Astronomy and astrophysics
Year: 2018, Volume: 618, Pages: A160 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201834050 |
| Online Access: | Verlag, Volltext: http://dx.doi.org/10.1051/0004-6361/201834050 Verlag, Volltext: https://www.aanda.org/articles/aa/pdf/2018/10/aa34050-18.pdf 
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| Author Notes: | 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 |
| Summary: | <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. |
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| Item Description: | Gesehen am 21.02.2019 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/201834050 |