The University of Southampton
University of Southampton Institutional Repository

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - IV. Observations of frequency doubling and tripling in VW Hyi

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - IV. Observations of frequency doubling and tripling in VW Hyi
Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - IV. Observations of frequency doubling and tripling in VW Hyi
We present new observations of the rapid oscillations in the dwarf nova VW Hyi, made late in outburst. These dwarf nova oscillations (DNOs) increase in period until they reach 33 s, when a transition to a strong 1st harmonic and weak fundamental takes place. After further period increase the 2nd harmonic appears; often all three components are present simultaneously. This 1:2:3 frequency suite is similar to what has been seen in some neutron star and black hole X-Ray binaries, but has not previously been seen in a cataclysmic variable. When studied in detail the fundamental and 2nd harmonic vary similarly in phase, but the 1st harmonic behaves independently, though keeping close to twice the frequency of the fundamental. The fundamental period of the DNOs, as directly observed or inferred from the harmonics, increases to ~ 100 s before the oscillation disappears as the star reaches quiescence. Its maximum period is close to that of the ‘longer period’ DNOs observed in VW Hyi. The quasi-periodic oscillations (QPOs), which have fundamental periods 400 – 1000 s, behave in the sameway, showing 1st and 2nd harmonics at approximately the same times as the DNOs. We explore some possible models. One in which the existence of the 1st harmonic is due to transition from viewing a single accretion region to viewing two regions, and the rate of accretion onto the primary is modulated at the frequency of the 1st harmonic, as in the ‘beat frequency model’, can generate the suite of DNO frequencies observed. But the behaviour of the QPOs is not yet understood.
accretion, accretion discs – binaries, close, dwarf novae, cataclysmic variables – stars, oscillations – stars, individual, VW Hyi, EK TrA – x-rays, stars
1365-2966
1562-1576
Warner, Brian
0121587e-9b0d-423a-9579-c9b45487629b
Woudt, Patrick A.
078a12fd-3894-42c5-b3b6-1747a9325c51
Warner, Brian
0121587e-9b0d-423a-9579-c9b45487629b
Woudt, Patrick A.
078a12fd-3894-42c5-b3b6-1747a9325c51

Warner, Brian and Woudt, Patrick A. (2006) Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - IV. Observations of frequency doubling and tripling in VW Hyi. Monthly Notices of the Royal Astronomical Society, 367 (4), 1562-1576. (doi:10.1111/j.1365-2966.2006.10057.x).

Record type: Article

Abstract

We present new observations of the rapid oscillations in the dwarf nova VW Hyi, made late in outburst. These dwarf nova oscillations (DNOs) increase in period until they reach 33 s, when a transition to a strong 1st harmonic and weak fundamental takes place. After further period increase the 2nd harmonic appears; often all three components are present simultaneously. This 1:2:3 frequency suite is similar to what has been seen in some neutron star and black hole X-Ray binaries, but has not previously been seen in a cataclysmic variable. When studied in detail the fundamental and 2nd harmonic vary similarly in phase, but the 1st harmonic behaves independently, though keeping close to twice the frequency of the fundamental. The fundamental period of the DNOs, as directly observed or inferred from the harmonics, increases to ~ 100 s before the oscillation disappears as the star reaches quiescence. Its maximum period is close to that of the ‘longer period’ DNOs observed in VW Hyi. The quasi-periodic oscillations (QPOs), which have fundamental periods 400 – 1000 s, behave in the sameway, showing 1st and 2nd harmonics at approximately the same times as the DNOs. We explore some possible models. One in which the existence of the 1st harmonic is due to transition from viewing a single accretion region to viewing two regions, and the rate of accretion onto the primary is modulated at the frequency of the 1st harmonic, as in the ‘beat frequency model’, can generate the suite of DNO frequencies observed. But the behaviour of the QPOs is not yet understood.

This record has no associated files available for download.

More information

Published date: April 2006
Keywords: accretion, accretion discs – binaries, close, dwarf novae, cataclysmic variables – stars, oscillations – stars, individual, VW Hyi, EK TrA – x-rays, stars

Identifiers

Local EPrints ID: 47052
URI: http://eprints.soton.ac.uk/id/eprint/47052
ISSN: 1365-2966
PURE UUID: 378317d3-135f-4af6-ad74-ae412e48e315

Catalogue record

Date deposited: 24 Jul 2007
Last modified: 15 Mar 2024 09:29

Export record

Altmetrics

Contributors

Author: Brian Warner
Author: Patrick A. Woudt

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×