HST/WFC3 imaging of protostellar jets in Carina: [Fe II] emission tracing massive jets from intermediate-mass protostars

Megan Reiter, Nathan Smith

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17 Citations (Scopus)

Abstract

We present narrowband WFC3-UVIS and -IR images of four externally irradiated protostellar jets in the Carina nebula: HH666, HH901, HH902, and HH1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O stars, but despite the strong incident ionizing radiation, portions of the jet remain neutral. Near-IR [Fe II] images reveal dense, neutral gas that was not seen in previous studies of H-alpha emission. We show that near-IR [Fe II] emitting gas must be self-shielded from Lyman continuum photons, regardless of its excitation mechanism (shocks, FUV radiation, or both). High densities are required for the survival of Fe+ amid the strong Lyman continuum from Tr14, raising estimates of the mass-loss rates by an order of magnitude. Higher jet mass-loss rates require higher accretion rates onto their driving protostars, implying that these jets are driven by intermediate-mass (IM; ∼2-8 Msun) stars. Indeed, the IR driving sources of two of these outflows have luminosities that require IM protostars. All four of these HH jets are highly collimated, with opening angles of only a few degrees, similar to those observed in low-mass protostars. We propose that these jets reflect essentially the same outflow phenomenon seen in wide-angle molecular outflows associated with IM and high-mass protostars, but that the collimated atomic jet core is irradiated and rendered observable in Carina's harsh radiative environment. In more quiescent environments, this atomic core remains invisible, and outflows traced by shock-excited molecules in the outflow cavity give the impression that these outflows have a wider opening angle. Thus, the externally irradiated jets in Carina constitute a new view of collimated jets from IM protostars, and offer strong additional evidence that stars up to at least ∼8 Msun form by the same accretion mechanisms as low-mass stars.

Original languageEnglish (US)
Pages (from-to)2226-2239
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume433
Issue number3
DOIs
StatePublished - 2013

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protostars
tracing
outflow
stars
shock
accretion
continuums
O stars
neutral gases
radiation
nebulae
gas
ionizing radiation
narrowband
cavity
luminosity
cavities

Keywords

  • Herbig-Haro objects
  • ISM: jets and outflows
  • Stars: Formation
  • Stars: protostars

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

@article{59491fcb5d984340aa89efe067465af7,
title = "HST/WFC3 imaging of protostellar jets in Carina: [Fe II] emission tracing massive jets from intermediate-mass protostars",
abstract = "We present narrowband WFC3-UVIS and -IR images of four externally irradiated protostellar jets in the Carina nebula: HH666, HH901, HH902, and HH1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O stars, but despite the strong incident ionizing radiation, portions of the jet remain neutral. Near-IR [Fe II] images reveal dense, neutral gas that was not seen in previous studies of H-alpha emission. We show that near-IR [Fe II] emitting gas must be self-shielded from Lyman continuum photons, regardless of its excitation mechanism (shocks, FUV radiation, or both). High densities are required for the survival of Fe+ amid the strong Lyman continuum from Tr14, raising estimates of the mass-loss rates by an order of magnitude. Higher jet mass-loss rates require higher accretion rates onto their driving protostars, implying that these jets are driven by intermediate-mass (IM; ∼2-8 Msun) stars. Indeed, the IR driving sources of two of these outflows have luminosities that require IM protostars. All four of these HH jets are highly collimated, with opening angles of only a few degrees, similar to those observed in low-mass protostars. We propose that these jets reflect essentially the same outflow phenomenon seen in wide-angle molecular outflows associated with IM and high-mass protostars, but that the collimated atomic jet core is irradiated and rendered observable in Carina's harsh radiative environment. In more quiescent environments, this atomic core remains invisible, and outflows traced by shock-excited molecules in the outflow cavity give the impression that these outflows have a wider opening angle. Thus, the externally irradiated jets in Carina constitute a new view of collimated jets from IM protostars, and offer strong additional evidence that stars up to at least ∼8 Msun form by the same accretion mechanisms as low-mass stars.",
keywords = "Herbig-Haro objects, ISM: jets and outflows, Stars: Formation, Stars: protostars",
author = "Megan Reiter and Nathan Smith",
year = "2013",
doi = "10.1093/mnras/stt889",
language = "English (US)",
volume = "433",
pages = "2226--2239",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

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TY - JOUR

T1 - HST/WFC3 imaging of protostellar jets in Carina

T2 - [Fe II] emission tracing massive jets from intermediate-mass protostars

AU - Reiter, Megan

AU - Smith, Nathan

PY - 2013

Y1 - 2013

N2 - We present narrowband WFC3-UVIS and -IR images of four externally irradiated protostellar jets in the Carina nebula: HH666, HH901, HH902, and HH1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O stars, but despite the strong incident ionizing radiation, portions of the jet remain neutral. Near-IR [Fe II] images reveal dense, neutral gas that was not seen in previous studies of H-alpha emission. We show that near-IR [Fe II] emitting gas must be self-shielded from Lyman continuum photons, regardless of its excitation mechanism (shocks, FUV radiation, or both). High densities are required for the survival of Fe+ amid the strong Lyman continuum from Tr14, raising estimates of the mass-loss rates by an order of magnitude. Higher jet mass-loss rates require higher accretion rates onto their driving protostars, implying that these jets are driven by intermediate-mass (IM; ∼2-8 Msun) stars. Indeed, the IR driving sources of two of these outflows have luminosities that require IM protostars. All four of these HH jets are highly collimated, with opening angles of only a few degrees, similar to those observed in low-mass protostars. We propose that these jets reflect essentially the same outflow phenomenon seen in wide-angle molecular outflows associated with IM and high-mass protostars, but that the collimated atomic jet core is irradiated and rendered observable in Carina's harsh radiative environment. In more quiescent environments, this atomic core remains invisible, and outflows traced by shock-excited molecules in the outflow cavity give the impression that these outflows have a wider opening angle. Thus, the externally irradiated jets in Carina constitute a new view of collimated jets from IM protostars, and offer strong additional evidence that stars up to at least ∼8 Msun form by the same accretion mechanisms as low-mass stars.

AB - We present narrowband WFC3-UVIS and -IR images of four externally irradiated protostellar jets in the Carina nebula: HH666, HH901, HH902, and HH1066. These massive jets are unusual because they are bathed in UV radiation from dozens of nearby O stars, but despite the strong incident ionizing radiation, portions of the jet remain neutral. Near-IR [Fe II] images reveal dense, neutral gas that was not seen in previous studies of H-alpha emission. We show that near-IR [Fe II] emitting gas must be self-shielded from Lyman continuum photons, regardless of its excitation mechanism (shocks, FUV radiation, or both). High densities are required for the survival of Fe+ amid the strong Lyman continuum from Tr14, raising estimates of the mass-loss rates by an order of magnitude. Higher jet mass-loss rates require higher accretion rates onto their driving protostars, implying that these jets are driven by intermediate-mass (IM; ∼2-8 Msun) stars. Indeed, the IR driving sources of two of these outflows have luminosities that require IM protostars. All four of these HH jets are highly collimated, with opening angles of only a few degrees, similar to those observed in low-mass protostars. We propose that these jets reflect essentially the same outflow phenomenon seen in wide-angle molecular outflows associated with IM and high-mass protostars, but that the collimated atomic jet core is irradiated and rendered observable in Carina's harsh radiative environment. In more quiescent environments, this atomic core remains invisible, and outflows traced by shock-excited molecules in the outflow cavity give the impression that these outflows have a wider opening angle. Thus, the externally irradiated jets in Carina constitute a new view of collimated jets from IM protostars, and offer strong additional evidence that stars up to at least ∼8 Msun form by the same accretion mechanisms as low-mass stars.

KW - Herbig-Haro objects

KW - ISM: jets and outflows

KW - Stars: Formation

KW - Stars: protostars

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