The <i>Chandra</i> X-ray view of the power sources in Cepheus A

Schneider, P. C.; Günther, H. M.; Schmitt, J. H. M. M.

doi:10.1051/0004-6361/200912995

Cited by 6 publications

(4 citation statements)

References 34 publications

(78 reference statements)

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“…At the distance of NGC 6334 I(N), the 6 cm flux densities of these objects would be 0.04-0.9 mJy, a range that includes both VLA2 and H 2 O-C4. It is interesting to note that HW 8 and HW 9 are both X-ray sources with HW 8 postulated to be a pre-main sequence star (due to its high median photon energy), while the softer, brighter, and more variable HW 9 is consistent with activity on a B-type star (Schneider et al 2009). In NGC 6334 I(N), a recent Chandra X-ray survey finds seven sources in the field of Figure 2, but none of the detections correspond in position to within 1.…”

Section: Vla 2 and H 2 O-c4mentioning

confidence: 93%

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Hunter

Brogan

Cyganowski

et al. 2014

ApJ

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Using the Submillimeter Array (SMA) and Karl G. Jansky Very Large Array, we have imaged the massive protocluster NGC 6334 I(N) at high angular resolution (0. 5 ∼ 650 AU) from 6 cm to 0.87 mm, detecting 18 new compact continuum sources. Three of the new sources are coincident with previously identified H 2 O masers. Together with the previously known sources, these data bring the number of likely protocluster members to 25 for a protostellar density of ∼700 pc −3 . Our preliminary measurement of the Q-parameter of the minimum spanning tree is 0.82-close to the value for a uniform volume distribution. All of the (nine) sources with detections at multiple frequencies have spectral energy distributions consistent with dust emission, and two (SMA 1b and SMA 4) also have long wavelength emission consistent with a central hypercompact H ii region. Thermal spectral line emission, including CH 3 CN, is detected in six sources: LTE model fitting of CH 3 CN (J = 12-11) yields temperatures of 72-373 K, confirming the presence of multiple hot cores. The fitted LSR velocities range from −3.3 to −7.0 km s −1 , with an unbiased mean square deviation of 2.05 km s −1 , implying a protocluster dynamical mass of 410 ± 260 M . From analysis of a wide range of hot core molecules, the kinematics of SMA 1b are consistent with a rotating, infalling Keplerian disk of diameter 800 AU and enclosed mass of 10-30 M that is perpendicular (within 1• ) to the large-scale bipolar outflow axis. A companion to SMA 1b at a projected separation of 0. 45 (590 AU; SMA 1d), which shows no evidence of spectral line emission, is also confirmed. Finally, we detect one 218.4400 GHz and several 229.7588 GHz Class-I CH 3 OH masers.

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Section: Vla 2 and H 2 O-c4mentioning

confidence: 93%

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Hunter

Brogan

Cyganowski

et al. 2014

ApJ

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“…X-rays have been observed from jets of some low-mass protostars (e.g., from DG Tau by Güdel et al (2008) and Schneider & Schmitt (2008)). X-ray emission has also been seen from some high-mass protostellar sources (e.g., from Cep A by Schneider et al (2009)). However, in general, the study of protostellar jets via X-rays is more limited compared to radio observations.…”

Section: Discussionmentioning

confidence: 98%

Disk Wind Feedback from High-mass Protostars. IV. Shock-ionized Jets

Gardiner,

Tan,

Staff

et al. 2024

ApJ

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Massive protostars launch accretion-powered, magnetically collimated outflows, which play crucial roles in the dynamics and diagnostics of the star formation process. Here we calculate the shock heating and resulting free–free radio emission in numerical models of outflows of massive star formation within the framework of the Turbulent Core Accretion model. We postprocess 3D magnetohydrodynamic simulation snapshots of a protostellar disk wind interacting with an infalling core envelope, and calculate shock temperatures, ionization fractions, and radio free–free emission. We find heating up to ∼107 K and near-complete ionization in shocks at the interface between the outflow cavity and infalling envelope. However, line-of-sight averaged ionization fractions peak around ∼10%, in agreement with values reported from observations of massive protostar G35.20-0.74N. By calculating radio-continuum fluxes and spectra, we compare our models with observed samples of massive protostars. We find our fiducial models produce radio luminosities similar to those seen from low- and intermediate-mass protostars that are thought to be powered by shock ionization. Comparing to more massive protostars, we find our model radio luminosities are ∼10–100 times less luminous. We discuss how this apparent discrepancy either reflects aspects of our modeling related to the treatment of cooling of the post-shock gas or a dominant contribution in the observed systems from photoionization. Finally, our models exhibit 10 yr radio flux variability of ∼5%, especially in the inner 1000 au region, comparable to observed levels in some hypercompact H ii regions.

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“…First, we set a conservative median energy cut M E > 4.5 keV that corresponds to a hydrogen column density N H ≈ 2 × 10 23 (assuming solar abundances in the intervening gas) or A v > 100 mag (assuming standard interstellar gas-to-dust ratio in the intervening material) using the calibration og Getman et al (2010). The threshold M E > 4.5 keV was chosen partly from past studies of star forming regions where previously known Class I protostars were found to have M E ≥ 4 keV (e.g., Getman et al 2007;Schneider et al 2009;Principe et al 2014), and partly from examination of the spatial distribution of sources in MYStIX fields under more and less strict criterion. Lower criterion like M E > 3.5 or M E > 4.0 increases the number of X-ray sources in the fields that are randomly located in the field rather than concentrated around dense molecular cloud cores ( §2.4) and increases the number of sources seen in the older field NGC 2362 where no Class 0/I protostars are expected.…”

Section: Selection Criteriamentioning

confidence: 99%

YOUNG STELLAR POPULATIONS IN MYStIX STAR-FORMING REGIONS: CANDIDATE PROTOSTARS

Romine

Feigelson

Getman

et al. 2016

ApJ

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The Massive Young Star Forming Complex in Infrared and X-ray (MYStIX) project provides a new census on stellar members of massive star forming regions within 4 kpc. Here the MYStIX Infrared Excess catalog (MIRES) and Chandra-based X-ray photometric catalogs are mined to obtain high-quality samples of Class I protostars using criteria designed to reduce extragalactic and Galactic field star contamination. A total of 1,109 MYStIX Candidate Protostars (MCPs) are found in 14 star forming regions. Most are selected from protoplanetary disk infrared excess emission, but 20% are found from their ultrahard X-ray spectra from heavily absorbed magnetospheric flare emission. Two-thirds of the MCP sample is newly reported here. The resulting samples are strongly spatially associated with molecular cores and filaments on Herschel far-infrared maps. This spatial agreement and other evidence indicate that the MCP sample has high reliability with relatively few 'false positives' from contaminating populations. But the limited sensitivity and sparse overlap among the infrared and X-ray subsamples indicate that the sample is very incomplete with many 'false negatives'. Maps, tables, and source descriptions are provided to guide further study of star formation in these regions. In particular, the nature of ultrahard X-ray protostellar candidates without known infrared counterparts needs to be elucidated.

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The Chandra X-ray view of the power sources in Cepheus A

Cited by 6 publications

References 34 publications

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Subarcsecond Imaging of the NGC 6334 I(n) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate

Disk Wind Feedback from High-mass Protostars. IV. Shock-ionized Jets

YOUNG STELLAR POPULATIONS IN MYStIX STAR-FORMING REGIONS: CANDIDATE PROTOSTARS

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