Dipper discs not inclined towards edge-on orbits

Ansdell, Megan; Gaidos, Eric; Williams, Jonathan P.; Kennedy, Grant M.; Wyatt, M. C.; LaCourse, D.; Jacobs, T.; Mann, Andrew W.

doi:10.1093/mnrasl/slw140

Cited by 71 publications

(59 citation statements)

References 44 publications

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“…Evidence of misaligned inner discs has also been recently inferred for several systems using high-contrast optical/infrared images, which have revealed shadows in the outer disc cast by unseen inclined inner disc components (e.g., Marino et al 2015;Stolker et al 2016;Debes et al 2017; Benisty et al 2018;Casassus et al 2018). A notable example is the dipper J1604, which hosts a face-on transition disc resolved by ALMA (Ansdell et al 2016a) and variable shadows seen by VLT/SPHERE (Pinilla et al 2018a), suggesting a highly misaligned (∼70-90 • ) and dynamic inner disc component.…”

Section: Introductionmentioning

confidence: 81%

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

Ansdell

Gaidos

Hedges

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Dippers are a common class of young variable star exhibiting day-long dimmings with depths of up to several tens of percent. A standard explanation is that dippers host nearly edge-on (i d ≈ 70 • ) protoplanetary discs that allow close-in (<1 au) dust lifted slightly out of the midplane to partially occult the star. The identification of a face-on dipper disc and growing evidence of inner disc misalignments brings this scenario into question. Thus we uniformly (re)derive the inclinations of 24 dipper discs resolved with (sub-)mm interferometry from ALMA. We find that dipper disc inclinations are consistent with an isotropic distribution over i d ≈ 0 − 75 • , above which the occurrence rate declines (likely an observational selection effect due to optically thick disc midplanes blocking their host stars). These findings indicate that the dipper phenomenon is unrelated to the outer (>10 au) disc resolved by ALMA and that inner disc misalignments may be common during the protoplanetary phase. More than one mechanism may contribute to the dipper phenomenon, including accretion-driven warps and "broken" discs caused by inclined (sub-)stellar or planetary companions.

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Section: Introductionmentioning

confidence: 81%

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

Ansdell

Gaidos

Hedges

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…(Ansdell et al 2016a) host millimeter dust disks at a wide range of inclinations (Ansdell et al 2016b), at odds with the warped edge-on inner disk explanation of their variability. As suggested in Ansdell et al (2016b), misaligned inner and outer disks might explain this apparent dilemma, and our observations provide the first evidence for such a geometry in one of these systems. Furthermore, a misaligned inner and outer disk in AA Tau would present the interesting possibility of gap-crossing material periodically intersecting our line of sight (Figure 4).…”

Section: Relationship Between Disk Structure and Photometric Variabilitymentioning

confidence: 97%

A Multi-ringed, Modestly Inclined Protoplanetary Disk around AA Tau

Loomis

Öberg

Andrews

et al. 2017

ApJ

138

137

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AA Tau is the archetype for a class of stars with a peculiar periodic photometric variability thought to be related to a warped inner disk structure with a nearly edge-on viewing geometry. We present high resolution (∼0 2) ALMA observations of the 0.87 and 1.3mm dust continuum emission from the disk around AA Tau. These data reveal an evenly spaced three-ringed emission structure, with distinct peaks at 0 34, 0 66, and 0 99, all viewed at a modest inclination of 59°.1±0°.3 (decidedly not edge-on). In addition to this ringed substructure, we find nonaxisymmetric features, including a "bridge" of emission that connects opposite sides of the innermost ring. We speculate on the nature of this "bridge" in light of accompanying observations of HCO + and 13 CO (J=3-2) line emission. The HCO + emission is bright interior to the innermost dust ring, with a projected velocity field that appears rotated with respect to the resolved disk geometry, indicating the presence of a warp or inward radial flow. We suggest that the continuum bridge and HCO + line kinematics could originate from gap-crossing accretion streams, which may be responsible for the long-duration dimming of optical light from AA Tau.

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“…Interestingly, the LC of RX J1604.3-2130A also exhibits short-period "dipper" events (Rebull et al 2018;Ansdell et al 2016a). The dipper phenomenon is generally attributed to occultation of the stellar photosphere by clumps of dusty disc material (Ansdell et al 2016b) but this has typically been considered to require disc inclinations of at least ∼ 70 • .…”

Section: Rx J16043-2130amentioning

confidence: 99%

“…As the outer disc regions of RX J1604.3-2130A are observed close to face-on, they are unlikely to be responsible for the observed stellar occultation events. Ansdell et al (2016a) suggested the problem of observing a face-on outer disc and dipper LC phenomena could be reconciled via occultation of the stellar photosphere by accretion streams (McGinnis et al 2015;Bodman et al 2017) if an inner disk warp exists. Indirect evidence for optically thick material existing closer to the star in a plane inclined with respect to the outer disc has been inferred from the presence of shadows in the outer disc (Takami et al 2014;Pinilla et al 2018).…”

Section: Rx J16043-2130amentioning

confidence: 99%

Star–disc (mis-)alignment in Rho Oph and Upper Sco: insights from spatially resolved disc systems with K2 rotation periods

Davies

2019

Monthly Notices of the Royal Astronomical Society

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The discovery of close in, giant planets (hot Jupiters) with orbital angular momentum vectors misaligned with respect to the rotation axis of their host stars presents problems for planet formation theories in which planets form in discs with angular momentum vectors aligned with that of the star. Violent, high eccentricity migration mechanisms purported to elevate planetary orbits above the natal disc plane predict populations of proto-hot Jupiters which have not been observed with Kepler. Alternative theories invoking primordial star-disc misalignments have recently received more attention. Here, the relative alignment between stars and their protoplanetary discs is assessed for the first time for a sample of 20 pre-main-sequence stars. Recently published rotation periods derived from high quality, long duration, high cadence K2 light curves for members of the ρ Ophiuchus and Upper Scorpius star forming regions are matched with high angular resolution observations of spatially resolved discs and projected rotational velocities to determine stellar rotation axis inclination angles which are then compared to the disc inclinations. Ten of the fifteen systems for which the stellar inclination could be estimated are consistent with star-disc alignment while five systems indicate potential misalignments between the star and its disc. The potential for chance misalignment of aligned systems due to projection effects and characteristic measurement uncertainties is also investigated. While the observed frequency of apparent star-disc misalignments could be reproduced by a simulated test population in which 100% of systems are truly aligned, the distribution of the scale of inferred misalignment angles could not.

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Dipper discs not inclined towards edge-on orbits

Cited by 71 publications

References 44 publications

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

A Multi-ringed, Modestly Inclined Protoplanetary Disk around AA Tau

Star–disc (mis-)alignment in Rho Oph and Upper Sco: insights from spatially resolved disc systems with K2 rotation periods

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