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Kato, Takumi; Ito, Yoshiki; Yamanaka, Akihiro; Baba, Noriaki

doi:10.2320/materia.45.45

Cited by 3 publications

(8 citation statements)

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“…The data reveal seven consecutive dwarf nova outbursts over 7 http://archive.stsci.edu/kepler/documents.html 8 A Guest Observer Office target with KeplerID: 7659570 the quarter of varying magnitude, duration and interval, with a comparatively short duty cycle on the order of 10 days. One outburst is a superoutburst, confirming V334 Lyr as an SU UMa class object, first reported by Kato (1993).…”

Section: Discussionsupporting

confidence: 72%

“…It is a faint source, with a quiescent magnitude of V ≃ 19, and therefore has been observed sparsely until now. Optical photometry by Kato (1993) coincided with a bright epoch of V ≃ 14 and revealed the presence of putative 2.1948 ±0.0005 hour superhumps, indicating that this source is a member of the SU UMa class of dwarf novae. The normal outbursts occurred over a 16 ± 3 day cycle and the superoutburst recurred on a mean cycle of 110 days (Kato, Poyner & Kinnunen 2002).…”

Section: Introductionmentioning

confidence: 79%

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QUIESCENT SUPERHUMPS DETECTED IN THE DWARF NOVA V344 LYRAE BY KEPLER

Still

Howell

Wood

et al. 2010

ApJ

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The timing capabilities and sensitivity of Kepler, NASA's observatory to find Earth-sized planets within the habitable zone of stars, are well matched to the timescales and amplitudes of accretion disk variability in cataclysmic variables. This instrumental combination provides an unprecedented opportunity to test and refine stellar accretion paradigms with high-precision, uniform data, containing none of the diurnal or season gaps that limit ground-based observations. We present a 3-month, 1 minute cadence Kepler light curve of V344 Lyr, a faint, little-studied dwarf nova within the Kepler field. The light curve samples V344 Lyr during five full normal outbursts and one superoutburst. Surprisingly, the superhumps found during superoutburst continue to be detected during the following quiescent state and normal outburst. The fractional excess of superhump period over the presumed orbital period suggests a relatively high binary mass ratio in a system where the radius of the accretion disk must vary by less than 2% in order to maintain tidal precession throughout the extended episode of superhumping. Disk radius is less restricted if the quiescent signal identified tentatively as the orbital period is a negative superhump, generated by a retrograde-precessing accretion disk, tilted with respect to the binary orbital plane.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 79%

QUIESCENT SUPERHUMPS DETECTED IN THE DWARF NOVA V344 LYRAE BY KEPLER

Still

Howell

Wood

et al. 2010

ApJ

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“…The star V344 Lyr (KIC 7659570) is a SU UMa star that lies in the Kepler field. Kato (1993) observed the star during a superoutburst (V ∼ 14), and reported the detection of superhumps with a period P = 2.1948 ± 0.0005 hr. In a later study Kato et al (2002) reported that the DN outbursts have a recurrence timescale of 16 ± 3 d, and that the superoutbursts have a recurrence timescale of ∼110 d. Ak et al (2008) estimated a distance of 619 pc for the star using a period-luminosity relationship.…”

Section: Introductionmentioning

confidence: 99%

V344 LYRAE: A TOUCHSTONE SU UMa CATACLYSMIC VARIABLE IN THE KEPLER FIELD

Wood

Still

Howell

et al. 2011

ApJ

121

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We report on the analysis of the Kepler short-cadence (SC) light curve of V344 Lyr obtained during . The system is an SU UMa star showing dwarf nova outbursts and superoutbursts, and promises to be a touchstone for CV studies for the foreseeable future. The system displays both positive and negative superhumps with periods of 2.20 and 2.06-hr, respectively, and we identify an orbital period of 2.11-hr. The positive superhumps have a maximum amplitude of ∼0.25-mag, the negative superhumps a maximum amplitude of ∼0.8 mag, and the orbital period at quiescence has an amplitude of ∼0.025 mag. The quality of the Kepler data is such that we can test vigorously the models for accretion disk dynamics that have been emerging in the past several years. The SC data for V344 Lyr are consistent with the model that two physical sources yield positive superhumps: early in the superoutburst, the superhump signal is generated by viscous dissipation within the periodically flexing disk, but late in the superoutburst, the signal is generated as the accretion stream bright spot sweeps around the rim of the non-axisymmetric disk. The disk superhumps are roughly anti-phased with the stream/late superhumps. The V344 Lyr data also reveal negative superhumps arising from accretion onto a tilted disk precessing in the retrograde direction, and suggest that negative superhumps may appear during the decline of DN outbursts. The period of negative superhumps has a positiveṖ in between outbursts.

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“…I wonder if it is possible to recreate such an environment that was experienced by Japan? As shown in Table 2, at the conclusion of the 14 Temperature profiles measured at 5 mm below surface 15 (SSC: surface structure control cooling) 15 Fine surface structure obtained with newly devised cooling method 15 16 Effect of SSC cooling on ductility we think it is about time to work in this direction. Are we prepared for the next innovation to realise Bessemer's dream?…”

Section: Discussionmentioning

confidence: 99%

“…14), producing a significantly finer and ductile crystal structure. In the subsurface area, very fine structure and no film-like ferrite is observed 15 (Fig. 15) and, as shown in Fig.…”

Section: Transverse Cracksmentioning

confidence: 90%

Development of steel continuous casting in Japan: Has Bessemer’s dream come true?

Tomono

2015

Ironmaking & Steelmaking

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Cited by 3 publications

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QUIESCENT SUPERHUMPS DETECTED IN THE DWARF NOVA V344 LYRAE BY KEPLER

QUIESCENT SUPERHUMPS DETECTED IN THE DWARF NOVA V344 LYRAE BY KEPLER

V344 LYRAE: A TOUCHSTONE SU UMa CATACLYSMIC VARIABLE IN THE KEPLER FIELD

Development of steel continuous casting in Japan: Has Bessemer’s dream come true?

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