A variable asymmetry in the circumstellar disk of HH 30

Karl R. Stapelfeldt, Alan M. Watson, John E. Krist, Christopher J. Burrows, David Crisp, Gilda E. Ballester, John T. Clarke, Robin W. Evans, John S. Gallagher, Richard E. Griffiths, J. Jeff Hester, John G. Hoessel, Jon A. Holtzman, Jeremy R. Mould, Paul Scowen, John T. Trauger

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

We report Hubble Space Telescope observations of variability within the reflection nebulosity of HH 30, a compact bipolar nebula that is a nearly edge-on accretion disk system. A dramatic lateral asymmetry appeared in the upper reflection nebula in the spring of 1998, but was largely absent in 1994 and 1995 images. The variability timescale is much shorter than disk dynamical timescales at the projected radius of the asymmetry, which indicates that its origin is a variable illumination pattern projected onto the outer disk by changes in the inner disk or the central star. Orbital motion of coherent clumps or voids in the inner disk at radii of a few AU might produce such an effect. Another possibility recently proposed is accretion hot spots near the star's magnetic poles which produce broad beams of light sweeping across the disk as the star rotates. Simulated images of a disk illuminated by such a central "lighthouse" are a reasonable match to the bright lateral asymmetry in the upper nebula of HH 30. However, a model with identical opposed hot spots is excluded by the absence of a prominent asymmetry in the lower reflection nebula. Further temporal monitoring of the system is needed to better characterize the nebular variability and establish its physical origin.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume516
Issue number2 PART 2
StatePublished - May 10 1999

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asymmetry
reflection nebulae
hot spot
accretion
nebulae
timescale
stars
void
magnetic poles
radii
clumps
Hubble Space Telescope
accretion disks
voids
monitoring
illumination
orbits

Keywords

  • Accretion, accretion disks
  • Circumstellar matter
  • Stars: individual (HH 30)
  • Stars: pre-main-sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Stapelfeldt, K. R., Watson, A. M., Krist, J. E., Burrows, C. J., Crisp, D., Ballester, G. E., ... Trauger, J. T. (1999). A variable asymmetry in the circumstellar disk of HH 30. Astrophysical Journal, 516(2 PART 2).

A variable asymmetry in the circumstellar disk of HH 30. / Stapelfeldt, Karl R.; Watson, Alan M.; Krist, John E.; Burrows, Christopher J.; Crisp, David; Ballester, Gilda E.; Clarke, John T.; Evans, Robin W.; Gallagher, John S.; Griffiths, Richard E.; Hester, J. Jeff; Hoessel, John G.; Holtzman, Jon A.; Mould, Jeremy R.; Scowen, Paul; Trauger, John T.

In: Astrophysical Journal, Vol. 516, No. 2 PART 2, 10.05.1999.

Research output: Contribution to journalArticle

Stapelfeldt, KR, Watson, AM, Krist, JE, Burrows, CJ, Crisp, D, Ballester, GE, Clarke, JT, Evans, RW, Gallagher, JS, Griffiths, RE, Hester, JJ, Hoessel, JG, Holtzman, JA, Mould, JR, Scowen, P & Trauger, JT 1999, 'A variable asymmetry in the circumstellar disk of HH 30', Astrophysical Journal, vol. 516, no. 2 PART 2.
Stapelfeldt KR, Watson AM, Krist JE, Burrows CJ, Crisp D, Ballester GE et al. A variable asymmetry in the circumstellar disk of HH 30. Astrophysical Journal. 1999 May 10;516(2 PART 2).
Stapelfeldt, Karl R. ; Watson, Alan M. ; Krist, John E. ; Burrows, Christopher J. ; Crisp, David ; Ballester, Gilda E. ; Clarke, John T. ; Evans, Robin W. ; Gallagher, John S. ; Griffiths, Richard E. ; Hester, J. Jeff ; Hoessel, John G. ; Holtzman, Jon A. ; Mould, Jeremy R. ; Scowen, Paul ; Trauger, John T. / A variable asymmetry in the circumstellar disk of HH 30. In: Astrophysical Journal. 1999 ; Vol. 516, No. 2 PART 2.
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abstract = "We report Hubble Space Telescope observations of variability within the reflection nebulosity of HH 30, a compact bipolar nebula that is a nearly edge-on accretion disk system. A dramatic lateral asymmetry appeared in the upper reflection nebula in the spring of 1998, but was largely absent in 1994 and 1995 images. The variability timescale is much shorter than disk dynamical timescales at the projected radius of the asymmetry, which indicates that its origin is a variable illumination pattern projected onto the outer disk by changes in the inner disk or the central star. Orbital motion of coherent clumps or voids in the inner disk at radii of a few AU might produce such an effect. Another possibility recently proposed is accretion hot spots near the star's magnetic poles which produce broad beams of light sweeping across the disk as the star rotates. Simulated images of a disk illuminated by such a central {"}lighthouse{"} are a reasonable match to the bright lateral asymmetry in the upper nebula of HH 30. However, a model with identical opposed hot spots is excluded by the absence of a prominent asymmetry in the lower reflection nebula. Further temporal monitoring of the system is needed to better characterize the nebular variability and establish its physical origin.",
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