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T. Foster - One of the best experts on this subject based on the ideXlab platform.
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The Galactic Plane Region near $\ell$ = 93$\degr$ - III. Multi-wavelength emission from SNR 3C 434.1
Astronomy & Astrophysics, 2005Co-Authors: T. FosterAbstract:New Canadian Galactic Plane Survey radio continuum, ROSAT X-ray, and optical line observations of supernova remnant (SNR) 3C 434.1 (G94.0+1.0) are presented. A radio spectrum of index $\alpha=0.4$ (where $S\propto \nu ^{-\alpha }$) confirms this SNR's emission signature as predominantly synchrotron, and suggests the SNR is in the Sedov expansion phase. The morphology of the remnant is compared in X-ray, optical, and radio continuum, and the brightest emission in all three wavelength regimes is from the eastern hemisphere of 3C 434.1, which marks where the SNR shock is interacting with the inside wall of its stellar wind bubble (SWB) home. The system is determined to be 4.5 kpc distant, residing in the Perseus Arm Spiral shock. From a deep H α mosaic of the Region, $\lambda $656 nm H α line emission is observed that correlates well with radio synchrotron emission and anticorrelates with X-ray emission from the SNR. The origin of this optical emission is likely dense ($n_{\rm e}=40$ cm -3 ) cooling $\ion{H}{ii}$ from the wall of the SWB, where the SNR shock has penetrated and become radiative ($v_{\rm s}\sim 100$ km s -1 ). The X-ray spectrum of this SNR between 0.5 and 2.4 keV is well modelled by a single-temperature thermal plasma ($T_{\rm e}=4.5\times10^{6}$ K, $n_{\rm e}=0.2$ cm -3 ). The magnetic field of the bright radio synchrotron emission Region is found (under the assumption of near equipartition) to be $B\sim 15$ μ G, a factor of 3 compression of the ambient ISM field (5 μ G). The westward extension of 3C 434.1 is the result of ongoing free expansion of the shock into the lower density interior of the SWB. I use multiwavelength observations to arrive at a unique solution for an interaction model of 3C 434.1 with the SWB, from which the age ($t=25\,000$ yr) and mass ejected in the explosion ($M_{\rm ej}=15.5$ $M_{\odot }$) are determined. I also find an initial blast-wave velocity of 1350 km s -1 , typical of type 1b SNe.
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The Galactic Plane Region near ℓ = 93°. II. A stellar wind bubble surrounding SNR 3C 434.1
Astronomy & Astrophysics, 2004Co-Authors: T. Foster, D. Routledge, Roland KothesAbstract:New Canadian Galactic Plane Survey λ21 cm H line observations towards supernova remnant (SNR) 3C 434.1 (G94.0+1.0) are presented. We find a fragmented and thin-walled atomic hydrogen shell inside which the SNR is seen to be contained at v �− 80 km s −1 , which we report to be a highly evolved stellar wind bubble (SWB) associated with the remnant. A dark area in the midst of otherwise bright line emission is also seen near −71 km s −1 . An absorption profile to the extragalactic continuum source 4C 51.45 (superimposed on the shell's north face) allows us to probe the shell's optical depth, kinetic temperature and expansion velocity. The material in the dark area has the same properties as material in the fragmented shell, suggesting that the dark area is actually the far-side "cap" of the shell seen absorbing emission from warm background gas, the first instance of H Self Absorption (HISA) seen in such a structure. We show that the kinematic distance of 10 kpc derived from a flat Galactic rotation model is highly improbable, and that this bubble/SNR system is most likely resident in the Perseus Spiral Arm, lying 5.2 kpc distant. We model the SWB shell in three dimensions as a homologously expanding ellipsoid. Physical and dynamical characteristics of the bubble are determined, showing its advanced evolutionary state. Finally, from a photometric search for one or more stars associated with the SWB, we determine that three B0V stars and one O4V star currently inhabit this bubble, and that the progenitor of 3C 434.1 was at latest also an O4 type star.
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The galactic Plane Region near $\mathsf{\ell=93^\circ}$ : I. HII Region NRAO 655
Astronomy & Astrophysics, 2001Co-Authors: T. Foster, D. RoutledgeAbstract:We present new Canadian Galactic Plane Survey radio continuum and 21 cm HI line observations of NRAO 655 (G93.4+1.8), plus radio recombination line observations, and optical H -line observations. The radio spectrum of NRAO 655 conrms its emission as thermal. From the 21 cm HI data we nd an atomic hydrogen cavity associated with this object atv' 71: 5k m s 1 . The cavity corresponds in position and size to the brightest radio continuum emission from NRAO 655. The corresponding kinematic distance is 8.8 kpc, placing NRAO 655 in the Perseus Arm. NRAO 655's linear size is therefore 70 pc 130 pc. To conrm the21 cm HI velocity we present the rst recombination line detection of NRAO 655 (H158 line, v' 71 km s 1 ), and the rst observations of a molecular cloud coinciding with NRAO 655 (at v' 72 km s 1 ). The rst optical detection of 656 nm H emission line features in NRAO 655 is also presented, and the H emission line brightness is determined. We suggest that the eastward extension of this strongly asymmetric object originates in a champagne outflow, and we estimate its age. We show that a single early-type star cannot be responsible for the outflow, whereas a group of later-type stars would suce. A partial HI shell is seen adjacent to the brightest part of NRAO 655; we suggest that it has been formed by dissociation of H2 in the molecular cloud.
Ken Ebisawa - One of the best experts on this subject based on the ideXlab platform.
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chandra deep x ray observation of a typical galactic Plane Region and near infrared identification
The Astrophysical Journal, 2005Co-Authors: Ken Ebisawa, Masahiro Tsujimoto, A Paizis, Kenji Hamaguchi, Aya Bamba, Roc M Cutri, H Kaneda, Yoshitomo Maeda, G SatoAbstract:Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic Plane Region at (l,b) ≈ (285,00), where no discrete X-ray source had been reported previously. We have detected 274 new point X-ray sources (4 σ confidence), as well as strong Galactic diffuse emission within two partially overlapping ACIS-I fields (~250 arcmin2 in total). The point-source sensitivity was ~3 × 10-15 ergs s-1 cm-2 in the hard X-ray band (2-10 keV) and ~2 × 10-16 ergs s-1 cm-2 in the soft band (0.5-2 keV). The sum of all the detected point-source fluxes accounts for only ~10% of the total X-ray flux in the field of view. Even hypothesizing a new population of much dimmer and numerous Galactic point sources, the total observed X-ray flux cannot be explained. Therefore, we conclude that X-ray emission from the Galactic Plane has a truly diffuse origin. Removing point sources brighter than ~3 × 10-15 ergs s-1 cm-2 (2-10 keV), we have determined the Galactic diffuse X-ray flux to be 6.5 × 10-11 ergs s-1 cm-2 deg-2 (2-10 keV). Only 26 point sources were detected in both the soft and hard bands, indicating that there are two distinct classes of X-ray sources distinguished by their spectral hardness ratios. The surface number density of the hard sources is only slightly higher than that measured at the high Galactic latitude Regions, indicating that the majority of the hard sources are background AGNs. Following up the Chandra observation, we have performed a near-infrared (NIR) survey with SofI at ESO/NTT. Almost all the soft X-ray sources have been identified in the NIR, and their spectral types are consistent with main-sequence stars, suggesting that most of them are nearby X-ray-active stars. On the other hand, only 22% of the hard sources had NIR counterparts, which are presumably Galactic. From X-ray and NIR spectral study, they are most likely to be quiescent cataclysmic variables. Our observation suggests a population of 104 cataclysmic variables in the entire Galactic Plane fainter than ~2 × 1033 ergs s-1. We have carried out a precise spectral study of the Galactic diffuse X-ray emission excluding the point sources. Confirming previous results, we have detected prominent emission lines from highly ionized heavy elements in the diffuse emission. In particular, the central energy of the iron emission line was determined to be 6.52 keV (90% confidence), which is significantly lower than what is expected from a plasma in thermal equilibrium. The downward shift of the iron line center energy suggests nonequilibrium ionization states of the plasma or the presence of a nonthermal process to produce 6.4 keV fluorescent lines.
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chandra deep x ray observation of a typical galactic Plane Region and near infrared identification
arXiv: Astrophysics, 2005Co-Authors: Ken Ebisawa, Masahiro Tsujimoto, A Paizis, Kenji Hamaguchi, Aya Bamba, Roc M Cutri, H Kaneda, Yoshitomo Maeda, G SatoAbstract:Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic Plane Region at (l,b) ~ (28.5, 0.0), where no discrete X-ray source had been reported previously. We have detected 274 new point X-ray sources (4 sigma confidence) as well as strong Galactic diffuse emission within two partially overlapping ACIS-I fields (~250 arcmin^2in total). Sum of all the detected point source fluxes accounts for only ~ 10 % of the total X-ray flux in the field of view. Even hypothesizing a new population of much dimmer and numerous Galactic point sources, the total observed X-ray flux cannot be explained. Therefore, we conclude that X-ray emission from the Galactic Plane has truly diffuse origin. Only 26 point sources were detected both in the soft and hard bands, indicating that there are two distinct classes of the X-ray sources distinguished by the spectral hardness ratio. Surface number density of the hard sources is only slightly higher than that measured at the high Galactic latitude Regions, indicating that majority of the hard sources are background AGNs. Following up the Chandra observation, we have performed a near-infrared (NIR) survey with SOFI at ESO/NTT. Almost all the soft X-ray sources have been identified in NIR and their spectral types are consistent with main-sequence stars, suggesting most of them are nearby X-ray active stars. On the other hand, only 22 % of the hard sources had NIR counterparts, which are presumably Galactic. From X-ray and NIR spectral study, they are most likely to be quiescent cataclysmic variables. We have also carried out a precise spectral study of the Galactic diffuse X-ray emission excluding the point sources.
Roland Kothes - One of the best experts on this subject based on the ideXlab platform.
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The Galactic Plane Region near ℓ = 93°. II. A stellar wind bubble surrounding SNR 3C 434.1
Astronomy & Astrophysics, 2004Co-Authors: T. Foster, D. Routledge, Roland KothesAbstract:New Canadian Galactic Plane Survey λ21 cm H line observations towards supernova remnant (SNR) 3C 434.1 (G94.0+1.0) are presented. We find a fragmented and thin-walled atomic hydrogen shell inside which the SNR is seen to be contained at v �− 80 km s −1 , which we report to be a highly evolved stellar wind bubble (SWB) associated with the remnant. A dark area in the midst of otherwise bright line emission is also seen near −71 km s −1 . An absorption profile to the extragalactic continuum source 4C 51.45 (superimposed on the shell's north face) allows us to probe the shell's optical depth, kinetic temperature and expansion velocity. The material in the dark area has the same properties as material in the fragmented shell, suggesting that the dark area is actually the far-side "cap" of the shell seen absorbing emission from warm background gas, the first instance of H Self Absorption (HISA) seen in such a structure. We show that the kinematic distance of 10 kpc derived from a flat Galactic rotation model is highly improbable, and that this bubble/SNR system is most likely resident in the Perseus Spiral Arm, lying 5.2 kpc distant. We model the SWB shell in three dimensions as a homologously expanding ellipsoid. Physical and dynamical characteristics of the bubble are determined, showing its advanced evolutionary state. Finally, from a photometric search for one or more stars associated with the SWB, we determine that three B0V stars and one O4V star currently inhabit this bubble, and that the progenitor of 3C 434.1 was at latest also an O4 type star.
D. Routledge - One of the best experts on this subject based on the ideXlab platform.
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The Galactic Plane Region near ℓ = 93°. II. A stellar wind bubble surrounding SNR 3C 434.1
Astronomy & Astrophysics, 2004Co-Authors: T. Foster, D. Routledge, Roland KothesAbstract:New Canadian Galactic Plane Survey λ21 cm H line observations towards supernova remnant (SNR) 3C 434.1 (G94.0+1.0) are presented. We find a fragmented and thin-walled atomic hydrogen shell inside which the SNR is seen to be contained at v �− 80 km s −1 , which we report to be a highly evolved stellar wind bubble (SWB) associated with the remnant. A dark area in the midst of otherwise bright line emission is also seen near −71 km s −1 . An absorption profile to the extragalactic continuum source 4C 51.45 (superimposed on the shell's north face) allows us to probe the shell's optical depth, kinetic temperature and expansion velocity. The material in the dark area has the same properties as material in the fragmented shell, suggesting that the dark area is actually the far-side "cap" of the shell seen absorbing emission from warm background gas, the first instance of H Self Absorption (HISA) seen in such a structure. We show that the kinematic distance of 10 kpc derived from a flat Galactic rotation model is highly improbable, and that this bubble/SNR system is most likely resident in the Perseus Spiral Arm, lying 5.2 kpc distant. We model the SWB shell in three dimensions as a homologously expanding ellipsoid. Physical and dynamical characteristics of the bubble are determined, showing its advanced evolutionary state. Finally, from a photometric search for one or more stars associated with the SWB, we determine that three B0V stars and one O4V star currently inhabit this bubble, and that the progenitor of 3C 434.1 was at latest also an O4 type star.
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The galactic Plane Region near $\mathsf{\ell=93^\circ}$ : I. HII Region NRAO 655
Astronomy & Astrophysics, 2001Co-Authors: T. Foster, D. RoutledgeAbstract:We present new Canadian Galactic Plane Survey radio continuum and 21 cm HI line observations of NRAO 655 (G93.4+1.8), plus radio recombination line observations, and optical H -line observations. The radio spectrum of NRAO 655 conrms its emission as thermal. From the 21 cm HI data we nd an atomic hydrogen cavity associated with this object atv' 71: 5k m s 1 . The cavity corresponds in position and size to the brightest radio continuum emission from NRAO 655. The corresponding kinematic distance is 8.8 kpc, placing NRAO 655 in the Perseus Arm. NRAO 655's linear size is therefore 70 pc 130 pc. To conrm the21 cm HI velocity we present the rst recombination line detection of NRAO 655 (H158 line, v' 71 km s 1 ), and the rst observations of a molecular cloud coinciding with NRAO 655 (at v' 72 km s 1 ). The rst optical detection of 656 nm H emission line features in NRAO 655 is also presented, and the H emission line brightness is determined. We suggest that the eastward extension of this strongly asymmetric object originates in a champagne outflow, and we estimate its age. We show that a single early-type star cannot be responsible for the outflow, whereas a group of later-type stars would suce. A partial HI shell is seen adjacent to the brightest part of NRAO 655; we suggest that it has been formed by dissociation of H2 in the molecular cloud.
Myung Gyoon Lee - One of the best experts on this subject based on the ideXlab platform.
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A WISE Survey of New Star Clusters in the Central Plane Region of the Milky Way
The Astrophysical Journal, 2018Co-Authors: Jinhyuk Ryu, Myung Gyoon LeeAbstract:We present the discovery of new star clusters in the central Plane Region ($|l| 800$ Myr) and five are young (age $\approx4$ Myr).