Fragment production and survival in irradiated disks: A comprehensive cooling criterion

Kaitlin Kratter, Ruth A. Murray-Clay

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Accretion disks that become gravitationally unstable can fragment into stellar or substellar companions. The formation and survival of these fragments depends on the precarious balance between self-gravity, internal pressure, tidal shearing, and rotation. Disk fragmentation depends on two key factors: (1) whether the disk can get to the fragmentation boundary of Q = 1 and (2) whether fragments can survive for many orbital periods. Previous work suggests that to reach Q = 1, and have fragments survive, a disk must cool on an orbital timescale. Here we show that disks heated primarily by external irradiation always satisfy the standard cooling time criterion. Thus, even though irradiation heats disks and makes them more stable in general, once they reach the fragmentation boundary, they fragment more easily. We derive a new cooling criterion that determines fragment survival and calculate a pressure-modified Hill radius, which sets the maximum size of pressure-supported objects in a Keplerian disk. We conclude that fragmentation in protostellar disks might occur at slightly smaller radii than previously thought and recommend tests for future simulations that will better predict the outcome of fragmentation in real disks.

Original languageEnglish (US)
Article number1
JournalAstrophysical Journal
Volume740
Issue number1
DOIs
StatePublished - Oct 10 2011
Externally publishedYes

Fingerprint

fragmentation
fragments
cooling
irradiation
orbitals
radii
accretion
internal pressure
gravity
timescale
shearing
accretion disks
simulation
gravitation
heat

Keywords

  • Accretion
  • accretion disks
  • planetary systems
  • protoplanetary disks

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Fragment production and survival in irradiated disks : A comprehensive cooling criterion. / Kratter, Kaitlin; Murray-Clay, Ruth A.

In: Astrophysical Journal, Vol. 740, No. 1, 1, 10.10.2011.

Research output: Contribution to journalArticle

@article{c4806301d8544ba0aca11009badd5600,
title = "Fragment production and survival in irradiated disks: A comprehensive cooling criterion",
abstract = "Accretion disks that become gravitationally unstable can fragment into stellar or substellar companions. The formation and survival of these fragments depends on the precarious balance between self-gravity, internal pressure, tidal shearing, and rotation. Disk fragmentation depends on two key factors: (1) whether the disk can get to the fragmentation boundary of Q = 1 and (2) whether fragments can survive for many orbital periods. Previous work suggests that to reach Q = 1, and have fragments survive, a disk must cool on an orbital timescale. Here we show that disks heated primarily by external irradiation always satisfy the standard cooling time criterion. Thus, even though irradiation heats disks and makes them more stable in general, once they reach the fragmentation boundary, they fragment more easily. We derive a new cooling criterion that determines fragment survival and calculate a pressure-modified Hill radius, which sets the maximum size of pressure-supported objects in a Keplerian disk. We conclude that fragmentation in protostellar disks might occur at slightly smaller radii than previously thought and recommend tests for future simulations that will better predict the outcome of fragmentation in real disks.",
keywords = "Accretion, accretion disks, planetary systems, protoplanetary disks",
author = "Kaitlin Kratter and Murray-Clay, {Ruth A.}",
year = "2011",
month = "10",
day = "10",
doi = "10.1088/0004-637X/740/1/1",
language = "English (US)",
volume = "740",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Fragment production and survival in irradiated disks

T2 - A comprehensive cooling criterion

AU - Kratter, Kaitlin

AU - Murray-Clay, Ruth A.

PY - 2011/10/10

Y1 - 2011/10/10

N2 - Accretion disks that become gravitationally unstable can fragment into stellar or substellar companions. The formation and survival of these fragments depends on the precarious balance between self-gravity, internal pressure, tidal shearing, and rotation. Disk fragmentation depends on two key factors: (1) whether the disk can get to the fragmentation boundary of Q = 1 and (2) whether fragments can survive for many orbital periods. Previous work suggests that to reach Q = 1, and have fragments survive, a disk must cool on an orbital timescale. Here we show that disks heated primarily by external irradiation always satisfy the standard cooling time criterion. Thus, even though irradiation heats disks and makes them more stable in general, once they reach the fragmentation boundary, they fragment more easily. We derive a new cooling criterion that determines fragment survival and calculate a pressure-modified Hill radius, which sets the maximum size of pressure-supported objects in a Keplerian disk. We conclude that fragmentation in protostellar disks might occur at slightly smaller radii than previously thought and recommend tests for future simulations that will better predict the outcome of fragmentation in real disks.

AB - Accretion disks that become gravitationally unstable can fragment into stellar or substellar companions. The formation and survival of these fragments depends on the precarious balance between self-gravity, internal pressure, tidal shearing, and rotation. Disk fragmentation depends on two key factors: (1) whether the disk can get to the fragmentation boundary of Q = 1 and (2) whether fragments can survive for many orbital periods. Previous work suggests that to reach Q = 1, and have fragments survive, a disk must cool on an orbital timescale. Here we show that disks heated primarily by external irradiation always satisfy the standard cooling time criterion. Thus, even though irradiation heats disks and makes them more stable in general, once they reach the fragmentation boundary, they fragment more easily. We derive a new cooling criterion that determines fragment survival and calculate a pressure-modified Hill radius, which sets the maximum size of pressure-supported objects in a Keplerian disk. We conclude that fragmentation in protostellar disks might occur at slightly smaller radii than previously thought and recommend tests for future simulations that will better predict the outcome of fragmentation in real disks.

KW - Accretion

KW - accretion disks

KW - planetary systems

KW - protoplanetary disks

UR - http://www.scopus.com/inward/record.url?scp=80053533206&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80053533206&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/740/1/1

DO - 10.1088/0004-637X/740/1/1

M3 - Article

AN - SCOPUS:80053533206

VL - 740

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 1

ER -