Csi 2264: Characterizing Young Stars in NGC 2264 With Short-Duration Periodic Flux Dips in Their Light Curves

Stauffer, J. R.; Cody, Ann Marie; McGinnis, Pauline; Rebull, L. M.; Hillenbrand, Lynne A.; Turner, Neal J.; Carpenter, John M.; Plavchan, Peter; Carey, Sean; Terebey, S.; Morales-Calderón, M.; Alencar, S. H. P.; Bouvier, J.; Venuti, L.; Hartmann, L.; Calvet, Nuria; Micela, G.; Flaccomio, E.; Song, Inseok; Gutermuth, R. A.; Barrado, D.; Vrba, F. J.; Covey, Kevin R.; Padgett, D. L.; Herbst, W.; Gillen, Edward; Lyra, Wladimir; Guimarães, M. M.; Bouy, H.; Favata, F.

doi:10.1088/0004-6256/149/4/130

Cited by 97 publications

(87 citation statements)

References 69 publications

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“…There is some similarity between the light curves of some of the stars in Table 1 and some of the stars identified in recent years as "dippers" in Orion, NGC2264, and Upper Sco (Morales-Calderon et al 2011;Cody et al 2014;Stauffer et al 2015;Ansdell et al 2016); these stars are also sometimes referred to as AA Tau analogs (Bouvier et al 1999;Alencar et al 2010;McGinnis et al 2015). The light curves of AA Tau stars show a wide diversity, with most of them showing very broad and structured flux dips that are quite dissimilar from our Upper Sco stars and thus do not serve as plausible comparison objects.…”

Section: Could Variable Extinction From a Primordial Disk Explainmentioning

confidence: 56%

Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco

Stauffer

Cameron

Jardine

et al. 2017

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137

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Using K2 data, we identified 23 very-low-mass members of the ρ Oph and Upper Scorpius star-forming region as having periodic photometric variability not easily explained by well-established physical mechanisms such as star spots, eclipsing binaries, or pulsation. All of these unusual stars are mid-to-late M dwarfs without evidence of active accretion, and with photometric periods generally <1 day. Often the unusual light-curve signature takes the form of narrow flux dips; when we also have rotation periods from star spots, the two periods agree, suggesting that the flux dips are due to material orbiting the star at the Keplerian co-rotation radius. We sometimes see "statechanges" in the phased light-curve morphologies where ∼25% of the waveform changes shape on timescales less than a day; often, the "state-change" takes place immediately after a strong flare. For the group of stars with these sudden light-curve morphology shifts, we attribute their flux dips as most probably arising from eclipses of warm coronal gas clouds, analagous to the slingshot prominences postulated to explain transient Hα absorption features in AB Doradus and other rapidly rotating late-type stars. For another group of stars with somewhat longer periods, we find the short-duration flux dips to be highly variable on both short and long timescales, with generally asymmetric flux-dip profiles. We believe that these flux dips are due to particulate clouds possibly associated with a close-in planet or resulting from a recent collisional event.

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Section: Could Variable Extinction From a Primordial Disk Explainmentioning

confidence: 56%

Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco

Stauffer

Cameron

Jardine

et al. 2017

Self Cite

137

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“…In some cases where the stellar rotation is evident, such as the case of Mon 21, the dimming events have been observed to be synchronized with the stellar rotation period (Stauffer et al 2015). The coincidence between stellar rotation and the orbital period of transiting debris in this model is a natural consequence of disk-locking, where the inner disk edge is truncated near the corotation radius due to interactions with the stellar magnetosphere.…”

Section: Obscuration By a Circumstellar Disk?mentioning

confidence: 75%

“…The advent of highcadenceprecision photometry using space telescopes has revealed an unprecedented level of detail to this general class of variable young stars now called "dippers" (Cody et al 2014;Stauffer et al 2015;Ansdell et al 2016).…”

Section: Obscuration By a Circumstellar Disk?mentioning

confidence: 99%

A Transient Transit Signature Associated with the Young Star RIK-210

David

Petigura

Hillenbrand

et al. 2017

ApJ

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We find transienttransit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial resolution imaging revealed thatthe star is singleand radial velocity monitoring indicated that the dimming events cannot be due to an eclipsing stellar or brown dwarf companion. Archival and follow-up photometry suggest the dimming events are transient in nature. The variable morphology of the dimming events suggests they are not due to a singlespherical body. The ingress of each dimming event is always shallower than egress, as one would expect for an orbiting body with a leading tail. The dimming events are periodic and synchronous with the stellar rotation. However, we argue it is unlikely the dimming events could be attributed to anything on the stellar surface based on the observed depths and durations. Variable obscuration by a protoplanetary disk is unlikely on the basis that the star is not actively accreting and lacks the infrared excess associated with an inner disk. Rather, we explore the possibilities that the dimming events are due to magnetospheric clouds, a transiting protoplanet surrounded by circumplanetary dust and debris, eccentric orbiting bodies undergoing periodic tidal disruption, or an extended field of dust or debris near the corotation radius.

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“…differs from that of Alencar et al (2010), since we were able here to use the simultaneous FLAMES spectroscopy to refine our classification. In addition, Stauffer et al (2015) identified a new subclass of stars with variable extinction light curves that show periodic, shallow, and short-duration flux dips that are approximately Gaussian in shape. There is some overlap between this new class and the classical AA Tau systems, since a few AA Tau-like stars also present narrow dips superposed on the broad deep minima, as explained in their paper.…”

Section: Morphology Of the Corot Light Curvesmentioning

confidence: 99%

CSI 2264: Accretion process in classical T Tauri stars in the young cluster NGC 2264

Sousa

Alencar

Bouvier

et al. 2016

A&A

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Context. NGC 2264 is a young stellar cluster (∼3 Myr) with hundreds of low-mass accreting stars that allow a detailed analysis of the accretion process taking place in the pre-main sequence. Aims. Our goal is to relate the photometric and spectroscopic variability of classical T Tauri stars to the physical processes acting in the stellar and circumstellar environment, within a few stellar radii from the star. Methods. NGC 2264 was the target of a multiwavelength observational campaign with CoRoT, MOST, Spitzer, and Chandra satellites and photometric and spectroscopic observations from the ground. We classified the CoRoT light curves of accreting systems according to their morphology and compared our classification to several accretion diagnostics and disk parameters. Results. The morphology of the CoRoT light curve reflects the evolution of the accretion process and of the inner disk region. Accretion burst stars present high mass-accretion rates and optically thick inner disks. AA Tau-like systems, whose light curves are dominated by circumstellar dust obscuration, show intermediate mass-accretion rates and are located in the transition of thick to anemic disks. Classical T Tauri stars with spot-like light curves correspond mostly to systems with a low mass-accretion rate and low mid-IR excess. About 30% of the classical T Tauri stars observed in the 2008 and 2011 CoRoT runs changed their light-curve morphology. Transitions from AA Tau-like and spot-like to aperiodic light curves and vice versa were common. The analysis of the Hα emission line variability of 58 accreting stars showed that 8 presented a periodicity that in a few cases was coincident with the photometric period. The blue and red wings of the Hα line profiles often do not correlate with each other, indicating that they are strongly influenced by different physical processes. Classical T Tauri stars have a dynamic stellar and circumstellar environment that can be explained by magnetospheric accretion and outflow models, including variations from stable to unstable accretion regimes on timescales of a few years.

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Csi 2264: Characterizing Young Stars in NGC 2264 With Short-Duration Periodic Flux Dips in Their Light Curves

Cited by 97 publications

References 69 publications

Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco

Orbiting Clouds of Material at the Keplerian Co-rotation Radius of Rapidly Rotating Low-mass WTTs in Upper Sco

A Transient Transit Signature Associated with the Young Star RIK-210

CSI 2264: Accretion process in classical T Tauri stars in the young cluster NGC 2264

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