Evidence that short-period AM CVn systems are diverse in outburst behaviour

Duffy, C.; Ramsay, Gavin; Steeghs, D.; Dhillon, V.; Sánchez, D. Mata; Ackley, K.; Dyer, M.; Lyman, J.; Ulaczyk, K.; Galloway, D. K.; O’Brien, P. T.; Noysena, K.; Nuttall, L. K.; Pollacco, D.

doi:10.1093/mnras/stab389

Cited by 15 publications

(20 citation statements)

References 45 publications

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“…A few systems that have been studied with targeted long ground-based photometric campaigns have been found to show some candidate NOs (e.g. Kato et al 2000;Levitan et al 2011;Duffy et al 2021), but many of these remain unconfirmed. Due to their short durations and inadequate cadence in the wide-field ground-based transient surveys, the NOs can be missed entirely, or merged or confused with a SO, and their durations and peak brightnesses cannot be adequately measured.…”

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confidence: 99%

TACOS: TESS AM CVn Outbursts Survey

Marcano

Sandoval

Maccarone

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Using TESS we are doing a systematic study of outbursting AM CVn systems to place some limits on the current outbursts models. We present the TESS light curve (LC) for 9 AM CVns showing both superoutbursts (SOs) and normal outbursts (NOs). The continuous coverage of the outbursts with TESS allows us to place stringent limits on the duration and structures of the SOs and the NOs. We present evidence that in at least some of the systems enhanced mass transfer (EMT) has to be taken into account to explain the observed LC of the SOs and rebrighthening phase after the SOs. For others, the colour evolution from simultaneous observations in g and r with ZTF differs from previously reported colour evolution of longer period AM CVns where EMT is responsible for the SO. We also find that due to the lack of sufficiently high cadence coverage the duration of many systems might have been overestimated in previous ground-based surveys. We report the SO duration for 6 AM CVns. We also found that precursors are a common feature of SOs in AM CVns and are seen in the LC of 5 of the 6 reported SOs. Finally the 10-minute and 2-minute cadence LCs from TESS also allowed us to find two new candidate orbital periods of AM CVns, both of which are in reasonably good agreement with the predictions for their periods based on their past outburst histories.

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confidence: 99%

TACOS: TESS AM CVn Outbursts Survey

Marcano

Sandoval

Maccarone

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The nine new AM CVn systems are typical for outbursting AM CVn systems (Duffy et al 2021) and show both outbursts and superoutbursts. In some cases, there are hints of "dips" a few days after the peak of a superoutburst.…”

Section: Characterization Of Nine New Am Cvn Systemsmentioning

confidence: 95%

“…The accretion rate is high and the systems are in a constant "high state" (e.g., Roelofs et al 2006b;Kupfer et al 2015;Wevers et al 2016;Green et al 2018b). Intermediate period systems (22  P  45 minutes) form an accretion disk and behave similarly to hydrogen-rich CVs; they show outbursts and superoutbursts (Kotko et al 2012), as well as flickering in their light curves (see Duffy et al 2021). As the orbital period increases, the outburst recurrence time increases exponentially (Levitan et al 2015) and the luminosity of the disk decreases (Nelemans et al 2004).…”

Section: Introductionmentioning

confidence: 99%

A Systematic Search for Outbursting AM CVn Systems with the Zwicky Transient Facility

Roestel

Creter

Kupfer

et al. 2021

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AM CVn systems are a rare type of accreting binary that consists of a white dwarf and a helium-rich, degenerate donor star. Using the Zwicky Transient Facility (ZTF), we searched for new AM CVn systems by focusing on blue, outbursting stars. We first selected outbursting stars using the ZTF alerts. We cross matched the candidates with Gaia and Pan-STARRS catalogs. The initial selection of candidates based on the Gaia BP-RP contains 1751 unknown objects. We used the Pan-STARRS g-r and r-i color in combination with the Gaia color to identify 59 strong AM CVn candidates. We obtained identification spectra of 35 sources, of which 18 are high-priority candidates, and discovered nine new AM CVn systems and one magnetic CV that shows only He-II lines. Using the outburst recurrence time, we estimate the orbital periods of the nine new AM CVn systems that are in the range of 29-50 minutes. We conclude that targeted follow up of blue, outbursting sources is an efficient method to find new AM CVn systems and we plan to follow up all candidates we identified to systematically study the population of outbursting AM CVn systems.

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“…A revision of the orbital and spin periods of the polar CD Ind based on TESS data led to a new interpretation of its accretion (Littlefield et al [330]), AM CVn systems are the more evolved friends of CVs, containing two white dwarfs where the larger and less massive one fills its Roche lobe and undergoes mass loss. The outbursts and superoutbursts of these objects remain poorly understood due to the diversity of behaviour as a function of orbital period (Duffy et al [331]). TESS has seen outbursts of several AM CVn systems and these observations are leading to an improved understanding of these extreme objects [331,332].…”

Section: Evolved Binariesmentioning

confidence: 99%

“…The outbursts and superoutbursts of these objects remain poorly understood due to the diversity of behaviour as a function of orbital period (Duffy et al [331]). TESS has seen outbursts of several AM CVn systems and these observations are leading to an improved understanding of these extreme objects [331,332].…”

Section: Evolved Binariesmentioning

confidence: 99%

Space-Based Photometry of Binary Stars: From Voyager to TESS

Southworth

2021

Universe

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Binary stars are crucial laboratories for stellar physics, so have been photometric targets for space missions beginning with the very first orbiting telescope (OAO-2) launched in 1968. This review traces the binary stars observed and the scientific results obtained from the early days of ultraviolet missions (OAO-2, Voyager, ANS, IUE), through a period of diversification (Hipparcos, WIRE, MOST, BRITE), to the current era of large planetary transit surveys (CoRoT, Kepler, TESS). In this time observations have been obtained of detached, semi-detached and contact binaries containing dwarfs, sub-giants, giants, supergiants, white dwarfs, planets, neutron stars and accretion discs. Recent missions have found a huge variety of objects such as pulsating stars in eclipsing binaries, multi-eclipsers, heartbeat stars and binaries hosting transiting planets. Particular attention is paid to eclipsing binaries, because they are staggeringly useful, and to the NASA Transiting Exoplanet Survey Satellite (TESS) because its huge sky coverage enables a wide range of scientific investigations with unprecedented ease. These results are placed into context, future missions are discussed, and a list of important science goals is presented.

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Evidence that short-period AM CVn systems are diverse in outburst behaviour

Cited by 15 publications

References 45 publications

TACOS: TESS AM CVn Outbursts Survey

TACOS: TESS AM CVn Outbursts Survey

A Systematic Search for Outbursting AM CVn Systems with the Zwicky Transient Facility

Space-Based Photometry of Binary Stars: From Voyager to TESS

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