The p and k-factors of the Classical Cepheid δ Cep
Date Issued
2018
Author(s)
Nardetto, Nicolas
•
•
Anderson, Richard I.
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Fokin, Andrei
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Gallenne, Alexandre
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Gieren, Wolfgang
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Graczyk, Dariusz
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Kervella, Pierre
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Mathias, Philippe
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Mérand, Antoine
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Mourard, Denis
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Neilson, Hilding
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Pietrzyński, Grzegorz
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Pilecki, Bogumił
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•
Storm, Jesper
Abstract
Probing the dynamical structure of Cepheid atmospheres is of primary importance in order to better constrain the cosmic distance ladder. It is indeed now well-known that the projection factor (or p-factor), that is used in the Baade-Wesselink method of distance determination of Cepheids, is sensitive to the atmospheric velocity gradient and other subtle dynamical effects. Relying on HARPS-N high resolution spectroscopic observations, we have measured the atmospheric velocity gradient of δ Cep for the first time, and we found an agreement with the hydrodynamical model of the star. Besides, the mysterious k-term, a residual γ-velocity of the order of 1-2 km s^{-1}, seen in HARPS-N data of δ Cep, is now physically understood thanks to recently published predicted spectroscopic properties of two-dimensional time-dependent Cepheid models.
Coverage
The RR Lyrae 2017 Conference. Revival of the Classical Pulsators: from Galactic Structure to Stellar Interior Diagnostics
All editors
Smolec, R.; Kinemuchi, K.; Anderson, R.I.
Volume
6
Start page
217
Conferenece
The RR Lyrae 2017 Conference. Revival of the Classical Pulsators: from Galactic Structure to Stellar Interior Diagnostics
Conferenece place
Niepołomice, Poland
Conferenece date
17-21 September, 2017
Issn Identifier
2545-1022
Ads BibCode
2018pas6.conf..217N
Rights
open.access
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