Near-infrared synthetic images of protostellar disks and envelopes

Daniel P Stark, B. A. Whitney, K. Stassun, K. Wood

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

We present a grid of near-infrared (IR) synthetic images of pre-main-sequence stars at different stages of evolution, which we simulate by varying envelope mass, disk radius and mass, and outflow cavity shape. Our aim is to determine how variations in physical properties of young stellar objects (e.g., mass infall rate, disk size) affect their observed colors and morphology, and use this information to highlight observable differences between different evolutionary states. We show that the near-IR colors are a function of envelope mass infall rate and inclination; hence both parameters must be constrained if colors are to be used to infer a source's true evolutionary state. Sources with more opaque envelopes have redder diffuse colors, because the scattered light suffers reddening as it propagates through the envelope. Somewhat counterintuitively, colors are reddest at intermediate inclinations (i ∼ 45°-70°) and then become bluer edge-on, where light is ∼100% scattered. Thus a source with relatively blue colors could be an evolved source or a younger source oriented edge-on. Importantly, we find that at inclinations where scattered light dominates, it is erroneous to derive extinction A V from observed colors; fully half of all objects will underestimate AV by at least an order of magnitude. We use our models to interpret six protostellar sources in the Taurus-Auriga molecular cloud observed with HST NICMOS. Of the six young stellar objects modeled in this paper, five require an infalling envelope to match the colors and should thus be classified as young embedded sources. The remaining source, Haro 6-5B, is a disk source, having already dispersed its envelope.

Original languageEnglish (US)
Pages (from-to)900-913
Number of pages14
JournalAstrophysical Journal
Volume649
Issue number2 I
DOIs
StatePublished - Oct 1 2006
Externally publishedYes

Fingerprint

near infrared
envelopes
color
inclination
pre-main sequence stars
molecular clouds
cavity
outflow
physical property
extinction
physical properties
grids
young
cavities
radii

Keywords

  • Circumstellar matter
  • Radiative transfer
  • Scattering
  • Stars: formation
  • Stars: pre-main-sequence

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Near-infrared synthetic images of protostellar disks and envelopes. / Stark, Daniel P; Whitney, B. A.; Stassun, K.; Wood, K.

In: Astrophysical Journal, Vol. 649, No. 2 I, 01.10.2006, p. 900-913.

Research output: Contribution to journalArticle

Stark, Daniel P ; Whitney, B. A. ; Stassun, K. ; Wood, K. / Near-infrared synthetic images of protostellar disks and envelopes. In: Astrophysical Journal. 2006 ; Vol. 649, No. 2 I. pp. 900-913.
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