The Spin-period History of Intermediate Polars

Patterson, Joseph; Miguel, Enrique de; Kemp, Jonathan; Dvorak, Shawn; Monard, B.; Hambsch, Franz-Josef; Vanmunster, Tonny; Skillman, David R.; Cejudo, D.; Campbell, Tut; Roberts, George; Jones, J. L.; Cook, Lewis M.; Bolt, Greg; Rea, Robert; Ulowetz, Joseph; Krajci, Thomas; Menzies, Kenneth; Lowther, S.; Goff, W.; Stein, William; Wood, M. A.; Myers, Gordon; Stone, G.; Uthas, H.; Karamehmetoglu, E.; Seargeant, Jim; McCormick, J.

doi:10.3847/1538-4357/ab863d

Cited by 21 publications

(12 citation statements)

References 30 publications

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“…The spin period of V1223 Sgr has steadily increased over the past 40 years (Patterson et al 2020), which comes as a surprise because this source is bright, and would be expected to spin up, as do most other bright IPs. This questions the assumption that V1223 Sgr is in spin equilibrium, spending equal amounts of time spinning up during high states and down during very low states, as noted by Patterson et al (2020). This makes it difficult to estimate the magnetic moment µ of the primary from the spin period but Norton et al (2004) suggest µ = 4 × 10 32 G cm 3 for this source.…”

Section: Rapid Outbursts In V1223 Sgrmentioning

confidence: 99%

Magnetically gated accretion model: Application to short bursts in the intermediate polar V1223 Sgr

Hameury

Lasota

Shaw

2022

A&A

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Context. Some intermediate polars (IPs) show outbursts that are much shorter than those observed in normal dwarf novae, and their origin remains unclear. Aims. We examine the case of V1223 Sgr, an intermediate polar that showed a short outburst in 1984, and compare the outburst characteristics with the predictions of the magnetospheric gating model. Methods. We extracted outburst profiles from the American Association of Variable Star Observers (AAVSO) archival data. We used our code to compute the time-dependent evolution of an accretion disc truncated by the white dwarf magnetic field, using a simple description of the interaction between the disc and the magnetic field, as in D’Angelo & Spruit (2010, MNRAS, 406, 1208). Results. We find that V1223 Sgr underwent a series of short outbursts, with a rise lasting for typically two to three hours, and a slightly longer decay. When applied to IPs, the model by D’Angelo & Spruit (2010, MNRAS, 406, 1208) accounts well for the observed outburst duration and intensity. However, we confirm that the model outcome depends sensitively on the assumptions of the rather poorly constrained model. We also searched the AAVSO database for short outbursts in other IPs, identifying individual short outbursts in FO Aqr, TV Col, NY Lup, and EI UMa, but no series such as those observed in V1223 Sgr. We also found a superoutburst, followed by a reflare in CTCV J2056−3014. Conclusions. Although the magnetic–gating accretion instability model is clearly responsible for the series of V1223 Sgr short outbursts and most probably for similar events in other IPs, the model describing this process needs improvement, in particular concerning the interaction between the magnetic field of the white dwarf and the accretion disc. This difficult task might benefit from further comparison of the model outcome with additional observations that show good time coverage and time resolution.

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Section: Rapid Outbursts In V1223 Sgrmentioning

confidence: 99%

Magnetically gated accretion model: Application to short bursts in the intermediate polar V1223 Sgr

Hameury

Lasota

Shaw

2022

A&A

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“…Runs of a length significant compared to the 4.99 h orbital period were split into sub-sections in order to be sensitive to possible orbital modulation, which is expected if the periodic signal contains orbital side-bands as is often the case in IPs (e.g. Kennedy et al 2016;Patterson et al 2020). Table 2 shows the measured times, along with cycle number counts whose derivation we detail in the next section.…”

Section: Measurement Of Pulse Timesmentioning

confidence: 99%

Optical detection of the rapidly spinning white dwarf in V1460 Her

Pelisoli,

Marsh,

Ashley

et al. 2021

Preprint

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Accreting magnetic white dwarfs offer an opportunity to understand the interplay between spin-up and spin-down torques in binary systems. Monitoring of the white dwarf spin may reveal whether the white dwarf spin is currently in a state of nearequilibrium, or of uni-directional evolution towards longer or shorter periods, reflecting the recent history of the system and providing constraints for evolutionary models. This makes the monitoring of the spin history of magnetic white dwarfs of high interest. In this paper we report the results of a campaign of follow-up optical photometry to detect and track the 39 sec white dwarf spin pulses recently discovered in Hubble Space Telescope data of the cataclysmic variable V1460 Her. We find the spin pulsations to be present in 𝑔-band photometry at a typical amplitude of 0.4 %. Under favourable observing conditions, the spin signal is detectable using 2-meter class telescopes. We measured pulse-arrival times for all our observations, which allowed us to derive a precise ephemeris for the white dwarf spin. We have also derived an orbital modulation correction that can be applied to the measurements. With our limited baseline of just over four years, we detect no evidence yet for spin-up or spin-down of the white dwarf, obtaining a lower limit of |𝑃/ 𝑃| > 4 × 10 7 years, which is already 4 to 8 times longer than the timescales measured in two other cataclysmic variable systems containing rapidly rotating white dwarfs, AE Aqr and AR Sco.

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“…Moreover, we notice that the bulk of the X-ray emission is interpreted as being due to a non-thermal (power-law) component (Mereghetti et al 2013), which is not expected for an accreting WD but it is the rule for accreting neutron stars Two lines of argument strongly suggest that the magnetic field of J2056 is low for an IP. The first is to assume that J2056, as is likely for IPs as a group (Patterson et al 2020), is in spin equilibrium. Consideration of material torques (which act to spin up the WD) and magnetic torques (which must balance the material torques in equilibrium) leads to the conclusion that the magnetic fields of fast-spinning IPs, such as J2056, are lower than their longer spin period cousins (see equation 21 and Figure 17 of Patterson 1994).…”

Section: Discussionmentioning

confidence: 99%