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Debris disc constraints on planetesimal formation

Krivov, Alexander V.; Ide, Aljoscha; Löhne, Torsten; Johansen, Anders LU and Blum, Jürgen (2018) In Monthly Notices of the Royal Astronomical Society 474(2). p.2564-2575
Abstract

Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical 'slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the... (More)

Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical 'slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentrationmodels - provided the objects are loosely bound 'pebble piles' as thesemodels also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a 'disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ~1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Circumstellar matter, Comets: general, Infrared: planetary systems, Planets and satellites: formation, Protoplanetary discs
in
Monthly Notices of the Royal Astronomical Society
volume
474
issue
2
pages
12 pages
publisher
Oxford University Press (OUP)
external identifiers
  • scopus:85042596934
ISSN
0035-8711
DOI
10.1093/mnras/stx2932
language
English
LU publication?
yes
id
2262b96d-158d-4c04-9ae8-700abc879c5b
date added to LUP
2018-03-09 08:21:38
date last changed
2018-11-21 21:38:33
@article{2262b96d-158d-4c04-9ae8-700abc879c5b,
  abstract     = {<p>Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical 'slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentrationmodels - provided the objects are loosely bound 'pebble piles' as thesemodels also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a 'disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ~1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.</p>},
  author       = {Krivov, Alexander V. and Ide, Aljoscha and Löhne, Torsten and Johansen, Anders and Blum, Jürgen},
  issn         = {0035-8711},
  keyword      = {Circumstellar matter,Comets: general,Infrared: planetary systems,Planets and satellites: formation,Protoplanetary discs},
  language     = {eng},
  number       = {2},
  pages        = {2564--2575},
  publisher    = {Oxford University Press (OUP)},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Debris disc constraints on planetesimal formation},
  url          = {http://dx.doi.org/10.1093/mnras/stx2932},
  volume       = {474},
  year         = {2018},
}