The ‘outside-in’ outburst of HT Cassiopeiae

Ioannou, Z.; Naylor, T.; Welsh, William F.; Catalán, M. S.; Worraker, W. J.; James, Nick

doi:10.1046/j.1365-8711.1999.03001.x

Cited by 30 publications

(28 citation statements)

References 39 publications

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“…14 and 58 spectra, with 300 and 180 s individual exposures, were taken during these runs, which covers about 0.8 and 2.0 orbital cycles. We note that the 1995 observations were performed about two months before the normal outburst, which was particularly well observed by Ioannou et al (1999). Because of electronic focus issues with the TV scanner during the 1995 observations, the spectral resolution of these data degrades rather suddenly toward longer wavelengths, especially beyond ∼4500 Å.…”

Section: Observations and Data Reductionmentioning

confidence: 72%

Voracious vortexes in cataclysmic variables

Neustroev

Zharikov

Borisov

2016

A&A

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We present multi-epoch, time-resolved optical spectroscopic observations of the dwarf nova HT Cas, which were obtained during 1986, 1992, 1995, and 2005 with the aim of studying the properties of emission structures in the system. We determined that the accretion disc radius, measured from the double-peaked emission-line profiles, is consistently large and lies within the range of 0.45-0.52a, where a is the binary separation. This is close to the tidal truncation radius r max = 0.52a. However, this result is not consistent with previous radius measurements. An extensive set of Doppler maps reveals a very complex emission structure of the accretion disc. Apart from a ring of disc emission, the tomograms display at least three areas of enhanced emission: the hot spot from the area of interaction between the gas stream and the disc, which is superposed on the elongated spiral structure, and the extended bright region on the leading side of the disc, which is opposite to the location of the hotspot. The position of the hotspot in all the emission lines is consistent with the trajectory of the gas stream. However, the peaks of emission are located in the range of distances 0.22-0.30a, which are much closer to the white dwarf than the disc edge. This suggests that the outer disc regions have a very low density, allowing the gas stream to flow almost freely before it starts to be seen as an emission source. We have found that the extended emission region on the leading side of the disc is always observed at the very edge of the large disc. Observations of other cataclysmic variables, which show a similar emission structure in their tomograms, confirm this conclusion. We propose that the leading side bright region is caused by irradiation of tidally thickened sectors of the outer disc, by the white dwarf and/or hot inner disc regions.

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Section: Observations and Data Reductionmentioning

confidence: 72%

Voracious vortexes in cataclysmic variables

Neustroev

Zharikov

Borisov

2016

A&A

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“…Therefore, an inner disc radius up to 2 × 10 9 cm is rather too large for a system with a fully ionised disc. Furthermore, a truncated disc with rin = 2.5 × 10 9 cm from Catalán 1995 is suggested by eclipse fitting in HT Cas during the rise to outburst (Ioannou et al 1999), but it should be lower during maximum/outburst. In the study of V2051 Oph (Baptista & Bortoletto 2004) and V4140 Sgr (Borges & Baptista 2005) the inner disc hole can be estimated from the innermost point in the radial brightness temperature distribution estimates deduced from eclipse mapping.…”

Section: Inner Disc Truncationmentioning

confidence: 97%

Rms–flux relation and fast optical variability simulations of the nova-like system MV Lyr

Dobrotka

Mineshige

Ness

2015

Monthly Notices of the Royal Astronomical Society

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The stochastic variability (flickering) of the nova-like system (subclass of cataclysmic variable) MV Lyr yields a complicated power density spectrum with four break frequencies. Scaringi et al. (2012a) analysed high-cadence Kepler data of MV Lyr, taken almost continuously over 600 days, giving the unique opportunity to study multicomponent Power Density Spectra (PDS) over a wide frequency range. We modelled this variability with our statistical model based on disc angular momentum transport via discrete turbulent bodies with an exponential distribution of the dimension scale. Two different models were used, a full disc (developed from the white dwarf to the outer radius of ∼ 10 10 cm) and a radially thin disc (a ring at a distance of ∼ 10 10 cm from the white dwarf) that imitates an outer disc rim. We succeed in explaining the two lowest observed break frequencies assuming typical values for a disc radius of 0.5 and 0.9 times the primary Roche lobe and an α parameter of 0.1 -0.4. The highest observed break frequency was also modelled, but with a rather small accretion disc with radius of 0.3 times the primary Roche lobe and a high α value of 0.9 consistent with previous findings by Scaringi (2014). Furthermore, the simulated light curves exhibit the typical linear rms-flux proportionality linear relation and the typical log-normal flux distribution. As the turbulent process is generating fluctuations in mass accretion that propagate through the disc, this confirms the general knowledge that the typical rms-flux relation is mainly generated by these fluctuations. In general a higher rms is generated by a larger amount of superposed flares which is compatible with a higher mass accretion rate expressed by a larger flux.

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“…Thus, the light variation of V2540 Oph cannot be probably attributed to the ellipsoidal effect of the companion star since the secondary star is too faint. Retter et al (1999) investigated the plausibility of the brightness modulation in the nova DN Gem originating from the irradiation of the secondary star using the model described in Somers, Mukai, & Naylor (1999) and Ioannou et al (1999). They concluded that an irradiated secondary star seems a likely source of the brightness modulations.…”

Section: Ellipsoidal Effect Of the Eecondary Starmentioning

confidence: 99%

The Orbital Period of Nova V2540 Ophiuchi (2002)

Retter

Liu³

2005

Publ. – Astron. Soc. Aust

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Abstract:We present the results of 26 nights of CCD photometry of the nova V2540 Oph (2002) from 2003 to 2004. We find a period of 0.284781 ± 0.000006 d (6.8347 ± 0.0001 h) in the data. Since this period was present in the light curves taken in both years, with no apparent change in its value or amplitude, we interpret it as the orbital period of the nova binary system. The mass-period relation for cataclysmic variables yields a secondary mass of about 0.75 ± 0.04 M . From maximum magnitude-rate of decline relation, we estimate a maximum absolute visual magnitude of M V = −6.2 ± 0.4 mag. This value leads to an uncorrected distance modulus of (m − M) = 14.7 ± 0.7. By using the interstellar reddening for the location of V2540 Oph, we find a rough estimate for the distance of 5.2 ± 0.8 kpc. We propose that V2540 Oph is either (1) a high-inclination cataclysmic variable showing a reflection effect of the secondary star, or having a spiral structure in the accretion disc, (2) a high-inclination intermediate polar system, or less likely (3) a polar.

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The ‘outside-in’ outburst of HT Cassiopeiae

Cited by 30 publications

References 39 publications

Voracious vortexes in cataclysmic variables

Voracious vortexes in cataclysmic variables

Rms–flux relation and fast optical variability simulations of the nova-like system MV Lyr

The Orbital Period of Nova V2540 Ophiuchi (2002)

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