Tidal disruption versus planetesimal collisions as possible origins for the dispersing dust cloud around Fomalhaut

Janson, Markus; Wu, Yanqin; Cataldi, Gianni; Brandeker, Alexis

doi:10.1051/0004-6361/202038589

Cited by 14 publications

(11 citation statements)

References 39 publications

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“…The dissociation timescales of the detected molecules imply that the gas may have been released in a series of events following a disruption of a large planetesimal in the recent past (Cataldi et al 2018). The disruption might have occurred as a result of a collision with another planetesimal (Jackson et al 2014;Lawler et al 2015) or through tidal disruption in a close encounter with a massive planet nested within the disk (Cataldi et al 2018;Janson et al 2020). A large number of fragments of different sizes would have been formed in the disruption, and acquired a range of eccentric orbits with different orbital elements, but which all converge once per orbit to the disruption location where they originally formed.…”

Section: Discussionmentioning

confidence: 99%

The far reaches of the β Pictoris debris disk

Janson

Brandeker

Olofsson

et al. 2021

A&A

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The nearby young star β Pictoris hosts a rich and complex planetary system, with at least two giant planets and a nearly edge-on debris disk that contains several dynamical subpopulations of planetesimals. While the inner ranges of the debris disk have been studied extensively, less information is known about the outer, fainter parts of the disk. Here we present an analysis of archival FORS V -band imaging data from 2003–2004, which have previously not been explored scientifically because the halo substructure of the bright stellar point spread function is complex. Through a high-contrast scheme based on angular differential imaging, with a forward-modelling approach to mitigate self-subtraction, we produced the deepest imaging yet for the outer range of the β Pic disk, and extracted its morphological characteristics. A brightness asymmetry between the two arms of the edge-on disk, which was previously noted in the inner disk, is even more pronounced at larger angular separations, reaching a factor ~10 around 1000 AU. Approaching 2000 AU, the brighter arm is visible at a surface brightness of 27–28 mag arcsec−2. Much like for the brightness asymmetry, a tilt angle asymmetry exists between the two arms that becomes increasingly extreme at large separations. The outer tilt angle of 7.2 deg can only be explained if the outer disk is farther from an edge-on inclination than the inner disk, or if its dust has a stronger scattering anisotropy, or (most likely) both. The strong asymmetries imply the presence of a highly eccentric kinematic disk component, which may have been caused by a disruptive event thought to have taken place at a closer-in location in the disk.

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Section: Discussionmentioning

confidence: 99%

The far reaches of the β Pictoris debris disk

Janson

Brandeker

Olofsson

et al. 2021

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“…Noteworthy examples include radial-velocity signals of an unclear nature and period in the time series of the nearby K dwarf HD 219134 (Motalebi et al 2015;Vogt et al 2015;Gillon et al 2017), the putative directly imaged planet around Fomalhaut (e.g. Kalas et al 2008;Janson et al 2020;Pearce et al 2021, and references therein), and a number of terrestrial-mass companions tentatively detected inside and outside the temperate zones of nearby M dwarfs, such as GJ 581 (which harbours the most highly debated habitable-zone system, see, Trifonov et al 2018, and references therein), τ Ceti (Tuomi et al 2013b;Feng et al 2017a), GJ 667 C (Delfosse et al 2013;Anglada-Escudé et al 2013;Feroz & Hobson 2014), and HD 40307 (Mayor et al 2009b;Tuomi et al 2013a;Díaz et al 2016).…”

Section: Exoplanetsmentioning

confidence: 99%

The 10 parsec sample in the Gaia era

Reylé

Jardine²,

Fouqué

et al. 2021

A&A

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Context. The nearest stars provide a fundamental constraint for our understanding of stellar physics and the Galaxy. The nearby sample serves as an anchor where all objects can be seen and understood with precise data. This work is triggered by the most recent data release of the astrometric space mission Gaia and uses its unprecedented high precision parallax measurements to review the census of objects within 10 pc. Aims. The first aim of this work was to compile all stars and brown dwarfs within 10 pc observable by Gaia and compare it with the Gaia Catalogue of Nearby Stars as a quality assurance test. We complement the list to get a full 10 pc census, including bright stars, brown dwarfs, and exoplanets. Methods. We started our compilation from a query on all objects with a parallax larger than 100 mas using the Set of Identifications, Measurements, and Bibliography for Astronomical Data database (SIMBAD). We completed the census by adding companions, brown dwarfs with recent parallax measurements not in SIMBAD yet, and vetted exoplanets. The compilation combines astrometry and photometry from the recent Gaia Early Data Release 3 with literature magnitudes, spectral types, and line-of-sight velocities. Results. We give a description of the astrophysical content of the 10 pc sample. We find a multiplicity frequency of around 28%. Among the stars and brown dwarfs, we estimate that around 61% are M stars and more than half of the M stars are within the range from M3.0 V to M5.0 V. We give an overview of the brown dwarfs and exoplanets that should be detected in the next Gaia data releases along with future developments. Conclusions. We provide a catalogue of 541 stars, brown dwarfs, and exoplanets in 339 systems, within 10 pc from the Sun. This list is as volume-complete as possible from current knowledge and it provides benchmark stars that can be used, for instance, to define calibration samples and to test the quality of the forthcoming Gaia releases. It also has a strong outreach potential.

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“…Such disruptions may happen through direct collisions between planetesimals (Jackson et al 2014;Lawler et al 2015), or, if a massive planet is present in the vicinity, planetesimals can also be tidally disrupted if they pass within the tidal disruption radius of the planet (Cataldi et al 2018). Collisions tend to dominate disruption rates in cases where the parent planetesimals are small, while tidal disruption dominates in cases where the planetesimals are large (Janson et al 2020). Jackson et al (2014) have shown that the collisional breakup of large planetesimals "naturally" produces strongly asymmetric rings, which are made of the small particles produced by the collisional cascade created in the initial breakup's aftermath.…”

Section: Considering Planetesimal Disruption As a Possible Origin For The Ringmentioning

confidence: 99%

Revealing asymmetrical dust distribution in the inner regions of HD 141569

Singh

Bhowmik

Boccaletti

et al. 2021

A&A

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Context. The combination of high-contrast imaging with spectroscopy and polarimetry offers a pathway to studying the grain distribution and properties of debris disks in exquisite detail. Here, we focus on the case of a gas-rich debris disk around HD 141569A, which features a multiple-ring morphology first identified with SPHERE in the near-infrared. Aims. We obtained polarimetric differential imaging with SPHERE in the H-band to compare the scattering properties of the innermost ring at 44 au with former observations in total intensity with the same instrument. In polarimetric imaging, we observed that the intensity of the ring peaks in the south-east, mostly in the forward direction, whereas in total intensity imaging, the ring is detected only at the south. This noticeable characteristic suggests a non-uniform dust density in the ring. With these two sets of images, we aim to study the distribution of the dust to solve for the actual dust distribution. Methods. We implemented a density function varying azimuthally along the ring and generated synthetic images both in polarimetry and in total intensity, which are then compared to the actual data. The search for the best-fit model was performed both with a grid-based and an MCMC approach. Using the outcome of this modelization, we further measured the polarized scattering phase function for the observed scattering angle between 33° and 147° as well as the spectral reflectance of the southern part of the ring between 0.98 and 2.1 μm. We tentatively derived the grain properties by comparing these quantities with MCFOST models and assuming Mie scattering. Results. We find that the dust density peaks in the south-west at an azimuthal angle of 220°~238° with a rather broad width of 61°~127°. The difference in the intensity distributions observed in polarimetry and total intensity is the result of this particular morphology. Although there are still uncertainties that remain in the determination of the anisotropic scattering factor, the implementation of an azimuthal density variation to fit the data proved to be robust. Upon elaborating on the origin of this dust density distribution, we conclude that it could be the result of a massive collision when we account for the effect of the high gas mass that is present in the system on the dynamics of grains. In terms of grain composition, our preliminary interpretation indicates a mixture of porous sub-micron sized astro-silicate and carbonaceous grains. Conclusions. The SPHERE observations have allowed, for the first time, for meaningful constraints to be placed on the dust distribution beyond the standard picture of a uniform ring-like debris disk. However, future studies with a multiwavelength approach and additional detailed modeling would be required to better characterize the grain properties in the HD 141569 system.

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Tidal disruption versus planetesimal collisions as possible origins for the dispersing dust cloud around Fomalhaut

Cited by 14 publications

References 39 publications

The far reaches of the β Pictoris debris disk

The far reaches of the β Pictoris debris disk

The 10 parsec sample in the Gaia era

Revealing asymmetrical dust distribution in the inner regions of HD 141569

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