Radio Observations of the Supernova Remnant HB 21

Erkes, J. W.; Dickel, John R.

doi:10.1086/110870

Cited by 11 publications

(8 citation statements)

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“…HB 21 has been a suspect for interaction with molecular clouds based on its radio appearance and the ambient molecular clouds (Erkes & Dickel 1969;Huang & Thaddeus 1986;T90). Erkes & Dickel (1969) suggested that the distorted boundaries with enhanced radio brightness might be the places where the SNR is interacting with dense ambient gas. Huang & Thaddeus (1986) found that the giant molecular cloud associated with Cyg OB 7 appears to be partially surrounding HB 21 (see also Dobashi et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Shocked Molecular Gas in the Supernova Remnant HB 21

Koo

Rho

Reach

et al. 2001

ApJ

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We report the discovery of the shocked molecular gas in the supernova remnant HB 21. We derive the physical parameters of the shocked gas from CO J=1-0 and J=2-1 line observations. We discuss the correlation of the shocked molecular gas with the previously detected, shocked atomic gas and the associated infrared emission.Comment: 24 pages, 10 figures, To appear in the ApJ, scheduled for the April 10, 2001 issue (v551

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Section: Introductionmentioning

confidence: 99%

Shocked Molecular Gas in the Supernova Remnant HB 21

Koo

Rho

Reach

et al. 2001

ApJ

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“…Kundu's result (1971) is that the remnant has a spectral index of -0.48 between 600-5000 MHz with a curvature below 600 MHz. Erkes and Dickel (1969) mentioned that the spectrum of HB21 is relatively straight in the central and southern parts with a mean slope of -0.4, but in the northern shell segment it is curved with a turnover at about 250 MHz. Between 1.4 GHz and 2.7 GHz, Haslam et al (1975) gave a temperature spectral index (T ∝ ν −β ) 1 of 2.8.…”

Section: Radio Morphology Of Hb21mentioning

confidence: 99%

“…It was discovered by Brown and Hazard (1953) at 159 MHz. Its radio continuum emission has been studied in considerable detail (e.g., Erkes & Dickel 1969;Kundu 1971;Kundu et al 1973;Hill 1974;Willis 1973;Haslam et al 1975;Reich et al 1983). Willis (1973) showed that the source has a spectral index of α = −0.4.…”

Section: Introductionmentioning

confidence: 99%

“…The shape of the remnant is not circular, and several results (Erkes & Dickel 1969) suggested that the northern V-shape boundary of the remnant may be due to collision with dense interstellar material (ISM). Also Tatematsu et al (1990) showed that an interstellar gas wall, consisting of atomic and molecular gas, is thought to have caused the straight eastern boundary of the remnant by impeding the expansion of the blast wave.…”

Section: Introductionmentioning

confidence: 99%

“…Willis also reported that the spectrum of the center region of the remnant may be much steeper, while the spectrum becomes flat in the northwest. Erkes and Dickel (1969) reported that there is a curved and flat spectrum in the northern shell and a straight spectrum in the southern shell.…”

Section: Introductionmentioning

confidence: 99%

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Radio Observations at 232 MHz and Multifrequency Spectral Studies of the SNR HB21

Zhang

Higgs

Landecker

et al. 2001

Chin. J. Astron. Astrophys.

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Radio observational results at 232 MHz and multifrequency studies of the supernova remnant (SNR) HB21 are presented. Its integrated flux density at 232 MHz is about 390 ± 30 Jy. Both the integrated spectral index and the spatial variations of spectral index of the remnant were calculated by combining the new map at 232 MHz with previously published maps made at 408, 1420, 2695, and 4750 MHz. The SNR has an integrated spectral index of about α = −0.43 (S ν ∝ ν α) between 232 and 4750 MHz. In general the spectral index varies from-0.5 in southeast and west regions of the remnant to-0.3 in the central region and near the northwest edge. The new data of 232 MHz reveal that there is interaction between the remnant and the surrounding gas along the east edge of the remnant which causes the spectrum flattening at low frequency, while the very good agreement between the structure of X-ray emission and the central flat spectrum area suggests that the existence of thermal emission is the reason of spectrum flattening in the area.

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