Period variations for the Cepheid VZ Cyg Virtual Observatory Resource

Authors
  1. Sirorattanakul K.
  2. Engle S.
  3. Pepper J.
  4. Wells M.
  5. Laney C.D.,Rodriguez J.E.
  6. Stassun K.G.
  7. Published by
    CDS
Abstract

The Cepheid Period-Luminosity law is a key rung on the extragalactic distance ladder. However, numerous Cepheids are known to undergo period variations. Monitoring, refining, and understanding these period variations allows us to better determine the parameters of the Cepheids themselves and of the instability strip in which they reside, and to test models of stellar evolution. VZ Cyg, a classical Cepheid pulsating at ~4.864 days, has been observed for over 100 years. Combining data from literature observations, the Kilodegree Extremely Little Telescope (KELT) transit survey, and new targeted observations with the Robotically Controlled Telescope (RCT) at Kitt Peak, we find a period change rate of dP/dt=-0.0642+/-0.0018 s/yr. However, when only the recent observations are examined, we find a much higher period change rate of dP/dt=-0.0923+/-0.0110 s/yr. This higher rate could be due to an apparent long-term (P~26.5 years) cyclic period variation. The possible interpretations of this single Cepheid's complex period variations underscore both the need to regularly monitor pulsating variables and the important benefits that photometric surveys such as KELT can have on the field. Further monitoring of this interesting example of Cepheid variability is recommended to confirm and better understand the possible cyclic period variations. Further, Cepheid timing analyses are necessary to fully understand their current behaviors and parameters, as well as their evolutionary histories.

Keywords
  1. variable-stars
  2. visible-astronomy
  3. Wide-band photometry
Bibliographic source Bibcode
2017AJ....154..217S
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/154/217
IVOA Identifier IVOID
ivo://CDS.VizieR/J/AJ/154/217
Document Object Identifer DOI
doi:10.26093/cds/vizier.51540217

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/154/217
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http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/154/217
IVOA Table Access TAP
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History

2018-08-14T08:01:10Z
Resource record created
2018-08-14T08:01:10Z
Created
2018-10-01T05:45:09Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr