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VLT near- to mid-IR imaging and spectroscopy of the M 17 UC1 - IRS5 region
Chen, Zhiwei,,; Nürnberger, Dieter E. A.; Chini, Rolf,; Jiang, Zhibo; Fang, Min
Source PublicationAstronomy and Astrophysics
AbstractAims. We investigate the surroundings of the hypercompact H II region M 17 UC1 to probe the physical properties of the associated young stellar objects and the environment of massive star formation. Methods. We use diffraction-limited near-IR (VLT/NACO) and mid-IR (VLT/VISIR) images to reveal the different morphologies at various wavelengths. Likewise, we investigate the stellar and nebular content of the region with VLT/SINFONI integral field spectroscopy with a resolution R ∼ 1500 at H + K bands. Results. Five of the seven point sources in this region show L-band excess emission. A geometric match is found between the H2 emission and near-IR polarized light in the vicinity of IRS5A, and between the diffuse mid-IR emission and near-IR polarization north of UC1. The H2 emission is typical for dense photodissociation regions (PDRs), which are initially far-ultraviolet pumped and repopulated by collisional de-excitation. The spectral types of IRS5A and B273A are B3-B7 V/III and G4-G5 III, respectively. The observed infrared luminosity LIR in the range 1-20 μm is derived for three objects; we obtain 2.0 × 103 Lo for IRS5A, 13 Lo for IRS5C, and 10 Lo for B273A. Conclusions. IRS5 might be a young quadruple system. Its primary star IRS5A is confirmed to be a high-mass protostellar object (∼9 Mo, ∼1 × 105 yrs); it might have terminated accretion due to the feedback from stellar activities (radiation pressure, outflow) and the expanding H II region of M 17. The object UC1 might also have terminated accretion because of the expanding hypercompact H II region, which it ionizes. The disk clearing process of the low-mass young stellar objects in this region might be accelerated by the expanding H II region. The outflows driven by UC1 are running south-north with its northeastern side suppressed by the expanding ionization front of M 17; the blue-shifted outflow lobe of IRS5A is seen in two types of tracers along the same line of sight in the form of H2 emission filament and mid-emission. The H2 line ratios probe the properties of M 17 SW PDR, which is confirmed to have a clumpy structure with two temperature distributions: warm, dense molecular clumps with nH > 105 cm-3 and T ≈ 575 K and cooler atomic gas with nH ∼ 3.7 × 103-1.5 × 104 cm-3 and T ∼ 50 - 200 K. © ESO 2015.
Subject Area天文和天体物理
Indexed BySCI
Document Type期刊论文
Recommended Citation
GB/T 7714
Chen, Zhiwei,,,Nürnberger, Dieter E. A.,Chini, Rolf,,et al. VLT near- to mid-IR imaging and spectroscopy of the M 17 UC1 - IRS5 region[J]. Astronomy and Astrophysics,2015,578.
APA Chen, Zhiwei,,,Nürnberger, Dieter E. A.,Chini, Rolf,,Jiang, Zhibo,&Fang, Min.(2015).VLT near- to mid-IR imaging and spectroscopy of the M 17 UC1 - IRS5 region.Astronomy and Astrophysics,578.
MLA Chen, Zhiwei,,,et al."VLT near- to mid-IR imaging and spectroscopy of the M 17 UC1 - IRS5 region".Astronomy and Astrophysics 578(2015).
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