Presternal ciliated cyst

Patterson, Jordan

doi:10.1001/archderm.120.2.240

Cited by 9 publications

(2 citation statements)

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“…This research uses observations of AR Sco from the AAVSO International Database contributed by GM and FJH, both of whom also participate in the Center for Backyard Astrophysics collaboration (Patterson 2012).…”

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confidence: 99%

High-time-resolution Photometry of AR Scorpii: Confirmation of the White Dwarf’s Spin-down

Stiller

Garnavich

Wood

et al. 2018

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The unique binary AR Scorpii consists of an asynchronously rotating, magnetized white dwarf (WD) that interacts with its red-dwarf companion to produce a large-amplitude, highly coherent pulsation every 1.97 minutes. Over the course of two years, we obtained thirty-nine hours of time-resolved, optical photometry of AR Sco at a typical cadence of 5 seconds to study this pulsation. We find that it undergoes significant changes across the binary orbital period and that its amplitude, phase, and waveform all vary as a function of orbital phase. We show that these variations can be explained by constructive and destructive interference between two periodic, double-peaked signals: the spin-orbit beat pulse, and a weaker WD spin pulse. Modelling of the light curve indicates that in the optical, the amplitude of the primary spin pulse is 50% of the primary beat amplitude, while the secondary maxima of the beat and spin pulses have similar amplitudes. Finally, we use our timings of the beat pulses to confirm the presence of the disputed spin-down of the WD. We measure a beat-frequency derivative ofν = (−5.14 ± 0.32) × 10 −17 Hz s −1 and show that this is attributable to the spin-down of the WD. This value is approximately twice as large as the estimate from Marsh et al. (2016) but is nevertheless consistent with the constraints established in Potter & Buckley (2018). Our precise measurement of the spin-down rate confirms that the decaying rotational energy of the magnetized white dwarf is sufficient to power the excess electromagnetic radiation emitted by the binary.

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confidence: 99%

High-time-resolution Photometry of AR Scorpii: Confirmation of the White Dwarf’s Spin-down

Stiller

Garnavich

Wood

et al. 2018

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“…Uninterrupted observations have led to several advances in our understanding of CVs and white dwarfs (WDs) (e.g., Patterson (2012); Provencal et al (2014)). Such observations provide a context for variability, separating shortterm variations from slower long-term trends.…”

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confidence: 99%

The K2 Light Curves and Stunted Outbursts of AC Cnc

Schlegel

Honeycutt

2019

ApJ

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We describe two observations of the nova-like cataclysmic variable AC Cnc obtained with Kepler during its revamped second mission (K2). Using the K2 1-minute cadence mode, the data were obtained during Campaigns 5 and 18. Campaign 5 (C05) lasted from ∼2015 Apr 27 to ∼2015 July 10, a total of 74.8 days, and yielded ∼106,000 measurements. Campaign 18 (C18) lasted from ∼2018 May 13 to ∼2018 July 2, a total of 50.7 days, yielding ∼72,000 measurements. The C05 light curve reveals two 'stunted outbursts' having properties consistent with stunted bursts observed from the ground; a stunted burst was underway during the C18 observation when it ended. During a stunted outburst, the primary eclipse is found to increase in depth but the residual brightness at mid-primary-eclipse remains nearly constant. By contrast, the secondary eclipse retains the same depth but the brightness at mid-secondary eclipse increases during outburst, following the orbital variations of the out-of-eclipse light. The eclipse ephemeris is statistically consistent with historical ephemerides and shows only marginal evidence for a period change. On the basis of the K2 data, we can not confirm a previously-reported non-orbital periodicity in AC Cnc.

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