Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

Unusual high-frequency oscillations in the Kepler δ Scuti star KIC 4840675

L. A. Balona, M. Breger, G. Catanzaro, M. S. Cunha, G. Handler, Z. Kołaczkowski, D. W. Kurtz, S. J. Murphy, E. Niemczura, M. Paparó, B. Smalley, R. Szabó, K. Uytterhoeven, J. L. Christiansen, K. Uddin, M. C. Stumpe

Abstract
We show that the star KIC 4840675 observed by Kepler is composed of three stars with a rapidly rotating A-type star and two solar-type fainter companions. The A-type star is a δ Scuti variable with a dominant mode and many other modes of lower amplitude, including several low-frequency variations. The low-frequency variation with highest amplitude can be interpreted as rotational modulation with the light curve changing with time. However, the most interesting aspect of this star is a triplet of independent modes in the range 118–129 d-1 (1.4–1.5 mHz), which is far outside the range of typical δ Scuti frequencies. We discuss the possibility that these modes could be solar-like oscillations, oscillations of the roAp type or due to an unseen pulsating compact companion.

Keywords
asteroseismology – binaries: spectroscopic – stars: individual: KIC 4840675 – stars: oscillations – stars: variables: δ Scuti

Monthly Notices of the Royal Astronomical Society
Volume 424, Page 1187
August 2012

>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website