The vertical structure of debris discs and the impact of gas

Olofsson, J.; Thébault, P.; Kral, Quentin; Bayo, A.; Boccaletti, A.; Godoy, N.; Henning, Thomas; Holstein, R. van; Maucó, Karina; Milli, J.; Montesinos, Matías; Rein, Hanno; Sefilian, Antranik A.

doi:10.1093/mnras/stac455

Cited by 27 publications

(28 citation statements)

References 120 publications

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“…Conversely, we might look for resolved systems displaying structures similar to the ones obtained in our investigation, even if they aren't part of a known multiple system, because not all disc-bearing host stars have been thoroughly vetted for companion stars. In this respect, the disc having the most interesting geometry is clearly the one surrounding TWA7, with a narrow birth ring at ∼ 25 au from which a single spiral arm is extending out to at least ∼ 50 au (Olofsson et al, 2018). A potential explanation could be a yet undetected companion located in the prolongation of this arm, producing a pattern that is very similar to what we obtain in our nominal case (Fig.…”

Section: Comparison To Observed Discssupporting

confidence: 85%

Debris discs in binaries: morphology and photometric signatures

Thebault,

Kral,

Olofsson

2020

Preprint

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Context. As about half of main-sequence stars reside in multiple star systems, it is important to consider the effect of binarity on the evolution of planetesimal belts in these complex systems. Aims. We aim to see whether debris belts evolving in between two stars may be impacted by the presence of the companion and whether this leaves any detectable signature that could be observed with current or future instruments. Methods. We consider a circumprimary parent body (PB) planetesimal belt that is placed just inside the stability limit between the 2 stars and use the state-of-the-art DyCoSS code to follow the coupled dynamical and collisional evolution of the dust produced by this PB belt. We explore several free parameters such as the belt's mass or the binary's mass ratio and orbital eccentricity. We use the GraTeR package to produce 2-D luminosity maps and system-integrated SEDs Results. We confirm a preliminary result obtained by earlier DyCoSS studies, which is that the coupled effect of collisional activity, binary perturbations and stellar radiation pressure is able to place and maintain a halo of small grains in the dynamically unstable region between the 2 stars. In addition, several prominent spatial structures are identified, notably a single spiral arm stretching all the way from the PB belt to the companion star. We also identify a fainter and more compact disc around the secondary star, which is non-native and feeds off small grains from the unstable halo. Both the halo, spiral arm and secondary disc should be detectable on resolved images by instruments with capacities similar to SPHERE. The system as a whole is depleted in small grains when compared to a companion-free case. This depletion leaves an imprint on the system's integrated SED, which appears colder than for the same parent body belt around a single star. This new finding could explain why the SED-derived location r disc of some unresolved discs-inbinaries places their primary belt in the dynamically "forbidden" region between the 2 stars: this apparent paradox could indeed be due to overestimating r disc when using empirical prescriptions valid for a single star case.

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Section: Comparison To Observed Discssupporting

confidence: 85%

Debris discs in binaries: morphology and photometric signatures

Thebault,

Kral,

Olofsson

2020

Preprint

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“…The orbital periods of the two other SB may be too short to detect such a PMa. HD 129590 has a bright nearly edge-on disc that was imaged in scattered light (Matthews et al 2017;Olofsson et al 2022).…”

Section: Spectroscopic Companionsmentioning

confidence: 99%

Radial Velocity Survey for Planets around Young stars (RVSPY)

Zakhozhay

Launhardt

Müller

et al. 2022

A&A

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Context. The occurrence rate and period distribution of (giant) planets around young stars is still not as well constrained as for older main-sequence stars. This is mostly due to the intrinsic activity-related complications and the avoidance of young stars in many large planet search programmes. Yet, dynamical restructuring processes in planetary systems may last significantly longer than the actual planet formation phase and may well extend long into the debris disc phase, such that the planet populations around young stars may differ from those observed around main-sequence stars. Aims. We introduce our Radial Velocity Survey for Planets around Young stars (RVSPY), which is closely related to the NaCo-ISPY direct imaging survey, characterise our target stars, and search for substellar companions at orbital separations smaller than a few au from the host star. Methods. We used the FEROS spectrograph, mounted to the MPG/ESO 2.2 m telescope in Chile, to obtain high signal-to-noise spectra and time series of precise radial velocities (RVs) of 111 stars, most of which are surrounded by debris discs. Our target stars have spectral types between early F and late K, a median age of 400 Myr, and a median distance of 45 pc. During the initial reconnaissance phase of our survey, we determined stellar parameters and used high-cadence observations to characterise the intrinsic stellar activity, searched for hot companions with orbital periods of up to 10 days, and derived the detection thresholds for longer-period companions. In our analysis we, have included archival spectroscopic data, spectral energy distribution, and data for photometric time series from the TESS mission.Results. For all target stars we determined their basic stellar parameters and present the results of the high-cadence RV survey and activity characterisation. We have achieved a median single-measurement RV precision of 6 m/s and derived the short-term intrinsic RV scatter of our targets (median 23 m/s), which is mostly caused by stellar activity and decays with an age from >100 m/s at <20 Myr to <20 m/s at >500 Myr. We analysed time series periodograms of the high-cadence RV data and the shape of the individual cross-correlation functions. We discovered six previously unknown close companions with orbital periods between 10 and 100 days, three of which are low-mass stars, and three are in the brown dwarf mass regime. We detected no hot companion with an orbital period <10 days down to a median mass limit of ∼1 M Jup for stars younger than 500 Myr, which is still compatible with the established occurrence rate of such companions around main-sequence stars. We found significant RV periodicities between 1.3 and 4.5 days for 14 stars, which are, however, all caused by rotational modulation due to starspots. We also analysed the data for TESS photometric time series and found significant periodicities for most of the stars. For 11 stars, the photometric periods are also clearly detected in the RV data. We also derived stellar rotation periods ranging from...

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“…However, the observed scale height varies as a function of wavelength, and factors other than the dynamical state of the collisional cascade can influence the measured scale height, particularly at short (optical and infrared, or OIR) wavelengths. Thébault (2009) showed that all debris disks have a natural minimum scale height at OIR wavelengths due to radiation pressure, stellar winds, and mutual grain collisions (which can also be altered by the gas content; see Olofsson et al 2022). Measurements of the scale height at OIR wavelengths therefore cannot be used to probe the dynamical conditions within a disk.…”

Section: Introductionmentioning

confidence: 99%

Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade

Vizgan

Hughes

Carter

et al. 2022

ApJ

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Debris disks are scaled-up analogs of the Kuiper Belt in which dust is generated by collisions between planetesimals. In the collisional cascade model of debris disks, the dust lost to radiation pressure and winds is constantly replenished by grinding collisions between planetesimals. The model assumes that collisions are destructive and involve large velocities; this assumption has not been tested beyond our solar system. We present 0.″25 (≈2.4 au) resolution observations of the λ = 450 μm dust continuum emission from the debris disk around the nearby M dwarf AU Microscopii with the Atacama Large Millimeter/submillimeter Array. We use parametric models to describe the disk structure, and a Monte Carlo Markov Chain (MCMC) algorithm to explore the posterior distributions of the model parameters; we fit the structure of the disk to both our data and archival λ = 1.3 mm data (Daley et al. 2019), from which we obtain two aspect ratio measurements at 1.3 mm (h 1300 = 0.025 − 0.002 + 0.008 ) and at 450 μm (h 450 = 0.019 − 0.001 + 0.006 ), as well as the grain-size distribution index q = 3.03 ± 0.02. Contextualizing our aspect ratio measurements within the modeling framework laid out in Pan & Schlichting (2012), we derive a power-law index of velocity dispersion as a function of grain size p = 0.28 ± 0.06 for the AU Mic debris disk. This result implies that smaller bodies are more easily disrupted than larger bodies by collisions, which is inconsistent with the strength regime usually assumed for such small bodies. Possible explanations for this discrepancy are discussed.

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The vertical structure of debris discs and the impact of gas

Cited by 27 publications

References 120 publications

Debris discs in binaries: morphology and photometric signatures

Debris discs in binaries: morphology and photometric signatures

Radial Velocity Survey for Planets around Young stars (RVSPY)

Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade

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