4 research outputs found
Investigating Protostellar Accretion-Driven Outflows Across the Mass Spectrum: JWST NIRSpec IFU 3-5~m Spectral Mapping of Five Young Protostars
Investigating Protostellar Accretion (IPA) is a Cycle 1 JWST program using
the NIRSpec+MIRI IFUs to obtain 2.9--28 m spectral cubes of five young
protostars with luminosities of 0.2 to 10,000 L in their primary
accretion phase. This paper introduces the NIRSpec 2.9--5.3 m data of the
inner 840-9000 au with spatial resolutions from 28-300 au. The spectra show
rising continuum emission, deep ice absorption, emission from H, H~I, and
[Fe~II], and the CO fundamental series in emission and absorption. Maps of the
continuum emission show scattered light cavities for all five protostars. In
the cavities, collimated jets are detected in [Fe~II] for the four ~L protostars, two of which are additionally traced in
Br-. Knots of [Fe~II] emission are detected toward the most luminous
protostar, and knots of [FeII] emission with dynamical times of ~yrs are
found in the jets of the others. While only one jet is traced in H, knots
of H and CO are detected in the jets of four protostars. H is seen
extending through the cavities showing they are filled by warm molecular gas.
Bright H emission is seen along the walls of a single cavity, while in
three cavities, narrow shells of H emission are found, one of which has an
[Fe~II] knot at its apex. These data show cavities containing collimated jets
traced in atomic/ionic gas surrounded by warm molecular gas in a wide-angle
wind and/or gas accelerated by bow shocks in the jets.Comment: 30 pages, 11 figure
Discovery of a collimated jet from the low luminosity protostar IRAS 162532429 in a quiescent accretion phase with the JWST
Investigating Protostellar Accretion (IPA) is a JWST Cycle~1 GO program that
uses NIRSpec IFU and MIRI MRS to obtain 2.9--28~m spectral cubes of young,
deeply embedded protostars with luminosities of 0.2 to 10,000~L and
central masses of 0.15 to 12~M. In this Letter, we report the
discovery of a highly collimated atomic jet from the Class~0 protostar
IRAS~162532429, the lowest luminosity source ( = 0.2
) in the IPA program. The collimated jet is detected in multiple
[Fe~II] lines, [Ne~II], [Ni~II], and H~I lines, but not in molecular emission.
The atomic jet has a velocity of about 169~~15~km\,s, after
correcting for inclination. The width of the jet increases with distance from
the central protostar from 23 to~60 au, corresponding to an opening angle of
2.6~~0.5\arcdeg. By comparing the measured flux ratios of various fine
structure lines to those predicted by simple shock models, we derive a shock
{speed} of 54~km\,s and a preshock density of
2.0~cm at the base of the jet. {From these quantities and
using a suite of jet models and extinction laws we compute a mass loss rate
between ~yr~.} The low mass loss rate
is consistent with simultaneous measurements of low mass accretion rate
(~yr) for IRAS~162532429 from
JWST observations (Watson et al. in prep), indicating that the protostar is in
a quiescent accretion phase. Our results demonstrate that very low-mass
protostars can drive highly collimated, atomic jets, even during the quiescent
phase.Comment: Accepted to ApJL. Comments and feedback welcom
300: An ACA 870 μm Continuum Survey of Orion Protostars and Their Evolution
We present an 870 μ m continuum survey of 300 protostars from the Herschel Orion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities on envelope scales ≤8000 au (20″) and resolve the structure of envelopes with 1600 au (4″) resolution, a factor of 3–5 improvement in angular resolution over existing single-dish 870 μ m observations. We compare the ACA observations to Atacama Large Millimeter/submillimeter Array 12 m array observations at 870 μ m with ∼0.″1 (40 au) resolution. Using the 12 m data to measure the fluxes from disks and the ACA data within 2500 au to measure the combined disk plus envelope fluxes, we calculate the 12 m/ACA 870 μ m flux ratios. Our sample shows a clear evolution in this ratio. Class 0 protostars are mostly envelope-dominated with ratios <0.5. In contrast, Flat Spectrum protostars are primarily disk-dominated with ratios near 1, although with a number of face-on protostars dominated by their envelopes. Class I protostars span the range from envelope to disk-dominated. The increase in ratio is accompanied by a decrease in the envelope fluxes and estimated mass infall rates. We estimate that 80% of the mass is accreted during the envelope-dominated phase. We find that the 12 m/ACA flux ratio is an evolutionary indicator that largely avoids the inclination and foreground extinction dependence of spectral energy distribution-based indicators
Investigating Protostellar Accretion-driven Outflows across the Mass Spectrum: JWST NIRSpec Integral Field Unit 3–5 μm Spectral Mapping of Five Young Protostars
Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9–28 μ m spectral cubes of five young protostars with luminosities of 0.2–10,000 L _⊙ in their primary accretion phase. This paper introduces the NIRSpec 2.9–5.3 μ m data of the inner 840–9000 au with spatial resolutions from 28 to 300 au. The spectra show rising continuum emission; deep ice absorption; emission from H _2 , H i , and [Fe ii ]; and the CO fundamental series in emission and absorption. Maps of the continuum emission show scattered light cavities for all five protostars. In the cavities, collimated jets are detected in [Fe ii ] for the four <320 L _⊙ protostars, two of which are additionally traced in Br α . Knots of [Fe ii ] emission are detected toward the most luminous protostar, and knots of [Fe ii ] emission with dynamical times of <30 yr are found in the jets of the others. While only one jet is traced in H _2 , knots of H _2 and CO are detected in the jets of four protostars. H _2 is seen extending through the cavities, showing that they are filled by warm molecular gas. Bright H _2 emission is seen along the walls of a single cavity, while in three cavities narrow shells of H _2 emission are found, one of which has an [Fe ii ] knot at its apex. These data show cavities containing collimated jets traced in atomic/ionic gas surrounded by warm molecular gas in a wide-angle wind and/or gas accelerated by bow shocks in the jets