Dippers and dusty disc edges: new diagnostics and comparison to model predictions

Bodman, Eva H. L.; Quillen, Alice C.; Ansdell, Megan; Hippke, Michael; Boyajian, Tabetha S.; Mamajek, Eric E.; Blackman, Eric G.; Rizzuto, Aaron C.; Kastner, Joel H.

doi:10.1093/mnras/stx1034

Cited by 92 publications

(94 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Orientation will further complicate our ability to observe a stable warp, since high inclinations are needed to generate occultation events. The average accretion rate through the disk may also play a role since the structure of the inner disk appears to vary with accretion rate (McClure et al 2013b) and the form of the optical variability, bursts versus occultations versus spots, appears to be broadly correlated with accretion rate (Bodman et al 2016;Sousa et al 2016). This connection between disk/ magnetosphere interactions and average accretion rate through the disk is independent of any of the infrared fluctuations induced by rapid accretion rate variability discussed earlier.…”

Section: Discussionmentioning

confidence: 86%

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Flaherty

DeMarchi

Muzerolle

et al. 2016

ApJ

View full text Add to dashboard Cite

Infrared variability is common among young stellar objects, with surveys finding daily to weekly fluctuations of a few tenths of a magnitude. Space-based observations can produce highly sampled infrared light curves, but are often limited to total baselines of about 1 month due to the orientation of the spacecraft. Here we present observations of the Chameleon I cluster, whose low declination makes it observable by the Spitzer Space Telescope over a 200-day period. We observe 30 young stellar objects with a daily cadence to better sample variability on timescales of months. We find that such variability is common, occurring in ∼80% of the detected cluster members. The change in [3.6]-[4.5] color over 200 days for many of the sources falls between that expected for extinction and fluctuations in disk emission. With our high cadence and long baseline we can derive power spectral density curves covering two orders of magnitude in frequency and find significant power at low frequencies, up to the boundaries of our 200-day survey. Such long timescales are difficult to explain with variations driven by the interaction between the disk and stellar magnetic field, which has a dynamical timescale of days to weeks. The most likely explanation is either structural or temperature fluctuations spread throughout the inner ∼0.5 au of the disk, suggesting that the intrinsic dust structure is highly dynamic.

show abstract

Section: Discussionmentioning

confidence: 86%

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Flaherty

DeMarchi

Muzerolle

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…The morphology of the dips is related to the disk inclination, orientation of the magnetic field dipole, and warp opacity. The short durations of the dips detected in GI Tau indicates a moderate inclination viewing angle (Bodman et al 2017). The shape of the dips depends on the ingress timescale, i.e., the timescale for the structure to move in front of the star.…”

Section: The Slow Warp Model For the Quasi-periodic Dips Of 2014-2015mentioning

confidence: 95%

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

Guo

Herczeg

Jose

et al. 2018

ApJ

View full text Add to dashboard Cite

The variability of young stellar objects is mostly driven by star-disk interactions. In long-term photometric monitoring of the accreting T Tauri star GI Tau, we detect extinction events with typical depths of DṼ 2.5 mag that last for days to months and often appear to occur stochastically. In 2014-2015, extinctions that repeated with a quasi-period of 21 days over several months are the first empirical evidence of slow warps predicted by magnetohydrodynamic simulations to form at a few stellar radii away from the central star. The reddening is consistent with =  R 3.85 0.5 V and, along with an absence of diffuse interstellar bands, indicates that some dust processing has occurred in the disk. The 2015-2016 multiband light curve includes variations in spot coverage, extinction, and accretion, each of which results in different traces in color-magnitude diagrams. This light curve is initially dominated by a month-long extinction event and a return to the unocculted brightness. The subsequent light curve then features spot modulation with a 7.03 day period, punctuated by brief, randomly spaced extinction events. The accretion rate measured from U-band photometry ranges from´-1.3 10 8 to´-1.1 10 10 M e yr −1 (excluding the highest and lowest 5% of high-and low-accretion rate outliers), with an average of4.7 -10 9 M e yr −1 . A total of 50% of the mass is accreted during bursts of >´-12.8 10 9 M e yr -1, which indicates limitations on analyses of disk evolution using single-epoch accretion rates.

show abstract

“…The dust interpretation is supported by dippers invariably having infrared emission in excess of that expected from the stellar photosphere, indicating the presence of a protoplanetary disc, as well as the dips often being shallower at longer wavelengths, where dust is less scattering (Morales-Calderón et al 2011;Cody et al 2014;Schneider et al 2018). An origin in the inner (<1 au) disc is suggested by the quasi-periodic dippers having periods of a few days, which is often indistinguishable from the stellar rotation period (Bodman et al 2017), as well as a positive correlation between dip depth and excess emission in the WISE 4.6µm band, which is sensitive to warm dust grains near the disc-star co-rotation radius around late-type stars (Ansdell et al 2016b).…”

Section: Introductionmentioning

confidence: 99%

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

View full text Add to dashboard Cite

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.

show abstract

Dippers and dusty disc edges: new diagnostics and comparison to model predictions

Cited by 92 publications

References 83 publications

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Spitzer Observations of Long-Term Infrared Variability Among Young Stellar Objects in Chamaeleon I

Star–Disk Interactions in Multiband Photometric Monitoring of the Classical T Tauri Star GI Tau

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

Contact Info

Product

Resources

About