HiRes DECONVOLUTION OF<i>SPITZER</i>INFRARED IMAGES

Velusamy, T.; Marsh, K. A.; Beichman, C. A.; Backus, C. R.; Thompson, Tom

doi:10.1088/0004-6256/136/1/197

Cited by 25 publications

(45 citation statements)

References 34 publications

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“…We can infer the distribution of gas from the distributions of cooler and warmer dust, as indexed by the 70 μm and 24 μm emission, respectively. Aside from feature i, the brightest 70 μm and 24 μm emission in this galaxy pair is from the eyelids (see the figure in Section 5.1 below and the HiRes deconvolution of the 70 μm and 24 μm images in Velusamy et al 2008), and thus the highest concentration of gas in IC 2163 is in the eyelids. Elmegreen et al (1995b) 21 atoms cm −2 , which corresponds to an A(UVM2) of 4.4 ± 2.2 mag.…”

Section: Overview Of the Systemmentioning

confidence: 84%

NGC 2207/Ic 2163: A Grazing Encounter With Large-Scale Shocks

Kaufman¹,

Grupe²,

Elmegreen³

et al. 2012

The Astronomical Journal

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Radio continuum, Spitzer infrared, optical, and XMM-Newton X-ray and ultraviolet observations (UVW1 and UVM2) are used to study large-scale shock fronts, young star complexes, and the galactic nuclei in the interacting galaxies NGC 2207/IC 2163. There are two types of large-scale shock fronts in this galaxy pair. The large-scale shock front along the rim of the ocular oval in IC 2163 has produced vigorous star formation in a dusty environment, bright in the Spitzer 8 μm and 24 μm images. In the outer part of the companion side of NGC 2207, a large-scale front attributed to halo scraping is particularly bright in the λ6 cm and λ20 cm radio continuum but not in any tracers of recent star formation (Hα, 8 μm, 24 μm, or ultraviolet emission) or in X-rays. This radio-continuum front may be from compression of the halo magnetic field on the back side of NGC 2207, between the two galaxies. The X-ray emission sets an upper limit to the gas density in the halo. Values of the flux density ratio S ν (8 μm)/S ν (6 cm) of prominent, kiloparsec-size, Spitzer/IRAC star-forming clumps in NGC 2207/IC 2163 are compared with those of giant radio H ii regions in M81. For the bright clumps in NGC 2207, the mean value of this ratio is the same as for the M81 H ii regions, whereas for the bright clumps on the rim of the IC 2163 ocular oval, the mean value is nearly a factor of two greater. Possible explanations for this are discussed. The galaxy pair has global values of the ratios of infrared-to-radio continuum flux density in the Spitzer 8 μm, 24 μm, and 70 μm bands, and the IRAS FIR significantly below the medians/means for large samples of galaxies. Feature i, a mini-starburst on an outer arm of NGC 2207 on its anti-companion side, is the most luminous 8 μm, 24 μm, 70 μm, radio continuum, and Hα source in the galaxy pair. We find evidence that a radio supernova was present in the core of feature i in 2001. X-ray emission is detected from the nucleus of NGC 2207 and from nine discrete sources whose X-ray luminosities make them possible candidates for Ultraluminous X-ray sources. One of these corresponds with the Type Ib SN 1999ec, which is also bright in the ultraviolet, and another may be a radio supernova or a background quasar. The X-ray luminosity of the NGC 2207 nucleus is log L 0.3-10.0 keV = 40.6 erg s −1 , which, together with its X-ray spectrum, suggests that this is a highly absorbed, low-luminosity, active galactic nucleus.

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Section: Overview Of the Systemmentioning

confidence: 84%

NGC 2207/Ic 2163: A Grazing Encounter With Large-Scale Shocks

Kaufman¹,

Grupe²,

Elmegreen³

et al. 2012

The Astronomical Journal

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“…This suggests that CM2 could be the driving source of the putative outflow traced by the extended, bipolar 4.5 μm emission. The existence of a bipolar outflow associated with this EGO has been recently supported (Velusamy et al 2008). The submillimeter map has been corrected for primary beam attenuation.…”

Section: Introductionmentioning

confidence: 81%

“…However, this could be a visual effect. Figure 23 shows the 870 μm and the 8.4 GHz ) continuum emission maps overlaid on the Spitzer 8.0 μm image obtained with the HiRES deconvolution algorithm (Velusamy et al 2008) and on the COMICS 25 μm image. As seen in this figure, the centimeter continuum emission associated with the UC Hii region CM1 is located closer to the SW IR peak than the submillimeter emission.…”

Section: Large-scale Kinematicsmentioning

confidence: 99%

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Beltrán

Sánchez-Monge

Cesaroni

et al. 2014

A&A

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Context. Theoretical scenarios propose that high-mass stars are formed by disk-mediated accretion. Aims. To test the theoretical predictions on the formation of massive stars, we wish to make a thorough study at high-angular resolution of the structure and kinematics of the dust and gas emission toward the high-mass star-forming region G35.03+0.35, which harbors a disk candidate around a B-type (proto)star. Methods. We carried out ALMA Cycle 0 observations at 870 μm of dust of typical high-density, molecular outflow, and cloud tracers with resolutions of <0. 5. Complementary Subaru COMICS 25 μm observations were carried out to trace the mid-infrared emission toward this star-forming region. Results. The submillimeter continuum emission has revealed a filamentary structure fragmented into six cores, called A-F. The filament could be in quasi-equilibrium taking into account that the mass per unit length of the filament, 200-375 M /pc, is similar to the critical mass of a thermally and turbulently supported infinite cylinder, ∼335 M /pc. The cores, which are on average separated by ∼0.02 pc, have deconvolved sizes of 1300-3400 AU, temperatures of 35-240 K, H 2 densities >10 7 cm −3 , and masses in the range 1-5 M , and they are subcritical. Core A, which is associated with a hypercompact Hii region and could be the driving source of the molecular outflow observed in the region, is the most chemically rich source in G35.03+0.35 with strong emission of typical hot core tracers such as CH 3 CN. Tracers of high density and excitation show a clear velocity gradient along the major axis of the core, which is consistent with a disk rotating about the axis of the associated outflow. The PV plots along the SE-NW direction of the velocity gradient show clear signatures of Keplerian rotation, although infall could also be present, and they are consistent with the pattern of an edge-on Keplerian disk rotating about a star with a mass in the range 5-13 M . The high t ff /t rot ratio for core A suggests that the structure rotates fast and that the accreting material has time to settle into a centrifugally supported disk. Conclusions. G35.03+0.35 is one of the most convincing examples of Keplerian disks rotating about high-mass (proto)stars. This supports theoretical scenarios according to which high-mass stars, at least B-type stars, would form through disk-mediated accretion.

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“…The digital correlator was configured in four spectral windows (with dual polarization) of 1875 MHz and 3840 channels each, providing a resolution of ∼0.4 km s −1 . The four spectral windows covered the frequency ranges [336 849.57-338 723.83 (Velusamy et al 2008) to the Spitzer/IRAC data. The submillimeter map has been corrected for primary beam attenuation.…”

Section: Alma Observationsmentioning

confidence: 99%

“…1a, we show the map of the ALMA 870 μm (350 GHz) continuum emission towards G35.20N overlaid on the Spitzer 4.5 μm image, whose resolution has been enhanced with HiRes (Velusamy et al 2008). The submillimeter continuum emission appears to trace an elongated structure in the SE-NW direction, perpendicular to the 4.5 μm extended emission, and located across the waist of the butterfly-shaped nebula seen in the infrared.…”

Section: Continuum Emissionmentioning

confidence: 99%

A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

Sánchez-Monge

Beltrán

Cesaroni

et al. 2014

A&A

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Context. The formation process of high-mass stars (with masses >8 M ) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. The advent of the Atacama Large Millimeter Array (ALMA) is expected to provide observational evidence to better constrain the theoretical scenarios. Aims. The present study aims at characterizing the high-mass star forming region G35.20−0.74 N, which is found associated with at least one massive outflow and contains multiple dense cores, one of them recently found associated with a Keplerian rotating disk. Methods. We used the radio-interferometer ALMA to observe the G35.20−0.74 N region in the submillimeter continuum and line emission at 350 GHz. The observed frequency range covers tracers of dense gas (e.g., H 13 CO + , C 17 O), molecular outflows (e.g., SiO), and hot cores (e.g., CH 3 CN, CH 3 OH). These observations were complemented with infrared and centimeter data. Results. The ALMA 870 μm continuum emission map reveals an elongated dust structure (∼0.15 pc long and ∼0.013 pc wide; full width at half maximum) perpendicular to the large-scale molecular outflow detected in the region, and fragmented into a number of cores with masses ∼1-10 M and sizes ∼1600 AU (spatial resolution ∼960 AU). The cores appear regularly spaced with a separation of ∼0.023 pc. The emission of dense gas tracers such as H 13 CO + or C 17 O is extended and coincident with the dust elongated structure. The three strongest dust cores show emission of complex organic molecules characteristic of hot cores, with temperatures around 200 K, and relative abundances 0.2-2 × 10 −8 for CH 3 CN and 0.6-5 × 10 −6 for CH 3 OH. The two cores with highest mass (cores A and B) show coherent velocity fields, with gradients almost aligned with the dust elongated structure. Those velocity gradients are consistent with Keplerian disks rotating about central masses of 4-18 M . Perpendicular to the velocity gradients we have identified a large-scale precessing jet/outflow associated with core B, and hints of an east-west jet/outflow associated with core A. Conclusions. The elongated dust structure in G35.20−0.74 N is fragmented into a number of dense cores that may form high-mass stars. Based on the velocity field of the dense gas, the orientation of the magnetic field, and the regularly spaced fragmentation, we interpret this elongated structure as the densest part of a 1D filament fragmenting and forming high-mass stars.

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HiRes DECONVOLUTION OFSPITZERINFRARED IMAGES

Cited by 25 publications

References 34 publications

NGC 2207/Ic 2163: A Grazing Encounter With Large-Scale Shocks

NGC 2207/Ic 2163: A Grazing Encounter With Large-Scale Shocks

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

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