Optical Filaments Research Articles

A Comparison of Ultraviolet, Optical, and X-Ray Imagery of Selected Fields in the Cygnus Loop

During the Astro-1 and Astro-2 Space Shuttle missions in 1990 and 1995, far ultraviolet (FUV) images of five 40' diameter fields around the rim of the Cygnus Loop supernova remnant were observed with the Ultraviolet Imaging Telescope (UIT). These fields sampled a broad range of conditions including both radiative and nonradiative shocks in various geometries and physical scales. In these shocks, the UIT B5 band samples predominantly CIV 1550 and the hydrogen two-photon recombination continuum. Smaller contri- butions are made by emission lines of HeII 1640 and OIII] 1665. We present these new FUV images and compare them with optical Halpha and [OIII], and ROSAT HRI X-ray images. Comparing the UIT images with those from the other bands provides new insights into the spatial variations and locations of these different types of emission. By comparing against shock model calculations and published FUV spectroscopy at select locations, we surmise that resonance scattering in the strong FUV permitted lines is widespread in the Cygnus Loop, especially in the bright optical filaments typically selected for observation in most previous studies.

A new actuator made of active composite material.

This paper describes a basic concept and elemental developments to realize a new actuator made of active composite material to be used for smart structures. In this study, CFRP prepreg was laminated on aluminum plate to develop an actuator and this laminate could perform unidirectional actuation. SiC continuous fiber/Al composite thin plate could also be used to form a modified type of actuator instead of using CFRP. As sensors to be embedded in this actuator, the following ones were developed. (1) A pre-notched optical fiber filament was embedded in matrix material without fracture and fractured in it at the notch, which enabled forming of an optical interference type strain sensor. (2) Nickel wire could be uniformly oxidized and embedded in aluminum matrix without fracture, which could successfully work as a temperature sensor and a strain sensor.

The Interstellar Matter in the Direction of the Supernova Remnant G296.5+10.0 and the Central X-Ray Source 1E 1207.4−5209

G296.5+10.0 is a high Galactic latitude supernova remnant (SNR), with a bilateral morphology in radio and X-rays. The compact X-ray source 1E 1207.4-5209, classified as a radio-quiet neutron star, is located very close to the remnant's center. We report on a survey of the H I distribution in a region of sky, 35 × 35, around the remnant, using the Australia Telescope Compact Array with a spatial resolution of about 35 and a velocity resolution of 0.82 km s-1. The H I distribution is quite smooth, with no obvious large-scale features that can explain the SNR bilateral morphology based on external factors. There are, however, three clouds that we do associate directly with the remnant. Optical filaments outline two smaller features, which appear to have been overtaken by the shock front and are cooling radiatively. Also, a high-velocity cloud gives a lower limit of ~35 km s-1 to the expansion velocity of the shock into the H I gas and a lower limit of ~2 × 1049 ergs for the kinetic energy injected by the supernova explosion into the surrounding interstellar medium. We estimate a distance to the SNR of d = 2.1 kpc and a total mass of at least 1900 M⊙ of associated H I gas. A hole in the H I column density is observed at the same position of the compact X-ray source 1E 1207.4-5209. This H I hole is at the same radial velocity as G296.5+10.0. We argue that this result constitutes concrete evidence that 1E 1207.4-5209 and G296.5+10.0 are physically associated.

Modeling the filamentation of ultra-short pulses in ionizing media

The filamentation of ultra-short pulses is investigated for plane waves propagating in gases ionized by multiphoton sources. The spatial growth rate of the filamentary modulational instability is computed as a function of the transverse wavenumber and frequency of periodic perturbations. Classical results for optical filamentation in Kerr media are recovered when the density of the electron plasma produced by ionization is close to zero. However, when the electron density is high enough, a beam with an input power above the Kerr self-focusing threshold is shown to stop forming filaments. Stability domains are expressed in terms of the electron density and pulse peak power, both for stationary perturbations and when the inertial plasma response together with the group-velocity dispersion of the wave are taken into account. These theoretical results are supported by numerical simulations and the influence of a delayed Kerr response on filament formation is finally discussed.

Centaurus A: multiple outbursts or bursting bubble?

We present new radio observations of the brighter region of the northern lobe (the northern middle lobe, NML) of Centaurus A obtained at 20 cm with the Australia Telescope Compact Array. The angular resolutions are ∼50 and ∼130 arcsec, therefore much higher than for the previously available radio images of this region. The most interesting feature detected in our images is a large-scale jet that connects the inner radio lobe and the NML, and which is imaged for the first time. The NML itself appears as diffuse emission with a relatively bright ridge on the eastern side. The radio morphology of Centaurus A and, in particular, its NML could be the result of a precessing jet that has undergone a strong interaction with the environment at least on the northern side. The very big drop in intensity between the inner jet and the large-scale jet can be explained with a sequence of bursts of activity at different epochs in the life of the source. Alternatively (or additionally) a ‘bursting bubble’ model is proposed to explain this big drop in intensity, which could also explain the good collimation of the large-scale jet. In this model, the plasma accumulated in the inner lobe would be able to ‘burst’ out only through one nozzle, which would be the region where the large-scale jet forms. The location of the nozzle would represent a region where the pressure gradient is more favourable. From the comparison between the radio emission and the regions of ionized gas discovered by Graham & Price (the so-called optical filaments) we find that the inner optical filament (∼8 kpc from the centre) falls about 2 arcmin (∼2 kpc) away from the large-scale radio jet. Thus, the inner filament does not seem to have experienced a direct interaction with the radio plasma. The complex velocity field observed in this filament could therefore be the result of strong instabilities produced by the ‘bursting bubble’. The outer filaments appear to be, in projection, closer to and aligned with the radio emission in the transition region between the jet and the lobe, suggesting a direct interaction with the radio jet. However, also in this case a more complicated interaction than assumed so far has to be occurring because of the relative position of the ionized and neutral gas regions compared with the radio jet as well as the kinematics of the ionized gas.

Neutral Hydrogen in the Direction of the Vela Supernova Remnant

?????We have carried out a study of the distribution and kinematics of the neutral hydrogen in the direction of the Vela supernova remnant (SNR). A field of 68 ? 54 centered at l = 2641, b = -16 was surveyed using the Parkes 64 m radio telescope (half-power beamwidth 147 at 21 cm). Nearly 2300 H I profiles were obtained with a grid spacing of 75. The presence of a thin, almost circular H I shell, centered at v = 1.6 ? 0.8 km s-1, is revealed. This shell delineates the outer border of the X-ray emission as shown in the ROSAT observations of Aschenbach, Egger, & Tr?mper and wraps around the receding part of the remnant. In addition, two higher velocity features possibly associated with Vela are observed at about -30 and 30 km s-1. These features are interpreted as gas accelerated by the expansion of the supernova shock. The low systemic velocity observed suggests a distance shorter than 500 pc for the Vela SNR. The H I shell is ~7? in diameter and expands at v ~ 30 km s-1. By assuming a distance of 350 pc, we calculate for this shell a linear radius of 22 pc, a swept-up mass of ~1200?2300 M?, and an atomic preshock density of ~1?2 cm-3. The kinetic energy transferred by the supernova shock into the interstellar medium is ~(1?2) ? 1049 ergs, while the initial energy of the explosion is estimated to be ~(1?2.5) ? 1051 ergs. We present the distribution of the column density of the neutral material absorbing the X-radiation, an essential parameter in the analysis of X-ray data. A comparison between the H I and H? emission suggests that the H I shell contains embedded dust that might be responsible for increased optical absorption in this region. On the other hand, the brightest arc-shaped optical filaments associated with the western side of Vela show good correspondence with the H I features. From a comparison between the H I and Molonglo Observatory Synthesis Telescope 843 MHz radio continuum emission, we find that the outermost arched radio filaments correlate well with the main ridge of the H I shell. No strong inhomogeneities were found in the ambient H I medium in the direction of Vela X (the central nebula, powered by the pulsar PSR B0833-45).

New Measurements of the Expansion of the Crab Nebula

ABSTRACTPublished images of the Crab Nebula have been scanned and measured to derive proper motions, the age of the nebula, and its point of origin. Astrometric reductions provided rms errors ranging from 0.″14 to 0.″31 in both axes for a given image. Proper motions of 50 optical filaments with a 53 yr baseline projected backward indicates the mean date of the supernova event as a.d. 1130 ± 16 yr, in good agreement with previous investigations by Trimble and Wyckoff & Murray but 76 yr after the reported outburst recorded by the Chinese astronomers in a.d. 1054. This result confirms the well‐known acceleration in the Crab's expansion. The image‐scanning technique demonstrates that accurate astrometric reductions can be achieved on a personal computer.

Amplification of Magnetic Fields in the Centers of Cluster Cooling Flows

In 1990, Soker & Sarazin predicted that cooling flows in clusters of galaxies would compress ambient intracluster magnetic fields until the magnetic pressure becomes comparable to the local thermal pressure. Strong, centrally enhanced magnetic fields were subsequently detected through Faraday rotation measurements of cooling-flow clusters. This compression of the magnetic field is one of the strongest circumstantial indicators of flow in cluster cooling flows. We present two additional mechanisms by which rotating cooling flows can generate strong, centrally enhanced magnetic fields: through the twisting of magnetic flux tubes and/or the operation of a fast α-ω dynamo. This will lead to strong, and possibly violent, magnetic activity in the inner ~10 kpc of cooling-flow clusters. Such magnetic activity, e.g., reconnection, can generate turbulence, heat, and relativistic particles, which can power the optical filaments that are observed within this spatial scale in many cooling flows and can form diffuse radio emission in the same region.

Hydrostatic pressure shows that lamellipodial motility in Ascaris sperm requires membrane-associated major sperm protein filament nucleation and elongation.

Sperm from nematodes use a major sperm protein (MSP) cytoskeleton in place of an actin cytoskeleton to drive their ameboid locomotion. Motility is coupled to the assembly of MSP fibers near the leading edge of the pseudopod plasma membrane. This unique motility system has been reconstituted in vitro in cell-free extracts of sperm from Ascaris suum: inside-out vesicles derived from the plasma membrane trigger assembly of meshworks of MSP filaments, called fibers, that push the vesicle forward as they grow (Italiano, J.E., Jr., T.M. Roberts, M. Stewart, and C.A. Fontana. 1996. Cell. 84:105-114). We used changes in hydrostatic pressure within a microscope optical chamber to investigate the mechanism of assembly of the motile apparatus. The effects of pressure on the MSP cytoskeleton in vivo and in vitro were similar: pressures >50 atm slowed and >300 atm stopped fiber growth. We focused on the in vitro system to show that filament assembly occurs in the immediate vicinity of the vesicle. At 300 atm, fibers were stable, but vesicles often detached from the ends of fibers. When the pressure was dropped, normal fiber growth occurred from detached vesicles but the ends of fibers without vesicles did not grow. Below 300 atm, pressure modulates both the number of filaments assembled at the vesicle (proportional to fiber optical density and filament nucleation rate), and their rate of assembly (proportional to the rates of fiber growth and filament elongation). Thus, fiber growth is not simply because of the addition of subunits onto the ends of existing filaments, but rather is regulated by pressure-sensitive factors at or near the vesicle surface. Once a filament is incorporated into a fiber, its rates of addition and loss of subunits are very slow and disassembly occurs by pathways distinct from assembly. The effects of pressure on fiber assembly are sensitive to dilution of the extract but largely independent of MSP concentration, indicating that a cytosolic component other than MSP is required for vesicle-association filament nucleation and elongation. Based on these data we present a model for the mechanism of locomotion-associated MSP polymerization the principles of which may apply generally to the way cells assemble filaments locally to drive protrusion of the leading edge.

The Asymmetric Wind in M82

We have obtained detailed imaging Fabry-Perot observations of the nearby galaxy M82, in order to understand the physical association between the high-velocity outflow and the starburst nucleus. The observed velocities of the emitting gas in M82 reveal a bipolar outflow of material, originating from the bright starburst regions in the galaxy's inner disk, but misaligned with respect to the galaxy spin axis. The deprojected outflow velocity increases with radius from 525 to 655 km/s. Spectral lines show double components in the centers of the outflowing lobes, with the H-alpha line split by ~300 km/s over a region almost a kiloparsec in size. The filaments are not simple surfaces of revolution, nor is the emission distributed evenly over the surfaces. We model these lobes as a composite of cylindrical and conical structures, collimated in the inner ~500 pc but expanding at a larger opening angle of ~25 degrees beyond that radius. We compare our kinematic model with simulations of starburst-driven winds in which disk material surrounding the source is entrained by the wind. The data also reveal a remarkably low [NII]/H-alpha ratio in the region of the outflow, indicating that photoionization by the nuclear starburst may play a significant role in the excitation of the optical filament gas, particularly near the nucleus.

Unusual Emission-Line Regions in the Tidal Arm of NGC 7318B in Stephan's Quintet

We report the optical spectroscopic discovery of two unusual emission-line regions in the tidal arm of a galaxy, NGC 7318B, that belongs to Stephan's Quintet. They are associated spatially with the unusual radio continuum emission discovered between the two galaxies NGC 7318B and NGC 7319. Taking account of both the large velocity widths of the emission lines, ~900 km s−1, and the strong [S II] λλ6717, 6731 emission with respect to Hα emission, we identify them as optical emission-line filaments of supernova remnants (SNRs) traced by the radio continuum and soft X-ray emission. Our narrowband Hα imaging shows that the unusual emission-line regions are indeed parts of the ionized bubble associated with one radio continuum peak. The required number of SNRs is estimated to be ~105-106 on the basis of the Hα, radio, and soft X-ray luminosities. Since there is no optical counterpart like a star cluster, it is suggested that ~105-106 supernova events occurred nearly simultaneously in this region several times 106 yr ago.

EUV and Microwave Observation of a Filament

AbstractSimultaneous XUV and microwave (μ – ѡ) observations of a solar filament, performed by several instruments onboard SOHO and by the Very Large Array (VLA), are analyzed. The filament appears as a dark structure, very similar in shape to the optical Hα filament, in all images taken in the transition region (TR) lines observed by CDS, in the Ne VIII lines observed by SUMER at λ = 770Å and 780Å and at all radio wavelengths with 1.7 cm ≤ λ ≤ 6 cm. Contrary to that, in six TR lines observed by SUMER at λ > 1300Å no trace of the filament, either in absorption or in emission, is visible. Finally, at λ = 21 cm, as well as in all images taken in coronal lines by CDS and EIT, a dark feature is present at the filament position, although with less defined contours than in the first-mentioned TR images. The constraints imposed by all these observations are discussed and interpreted.

X‐Ray and Optical Imagery of the SN 1006 Supernova Remnant

We present a high-resolution X-ray image of SN 1006: a mosaic of four ROSAT HRI images that together cover the entire supernova remnant. A well-defined shock front is observed surrounding the remnant shell. Comparison of the X-ray and radio images shows a close correspondence in general morphology, especially for the brightest features. Along the northeast limb of the shell, where the remnant is brightest in both bands, the X-ray/radio correspondence is striking in its detail. The data are consistent with a model in which the X-ray emission in this region results primarily from synchrotron radiation by the same population of shock-accelerated electrons that produce the radio emission. New optical images show Hα emission over a much greater portion of the remnant than has previously been reported. Newly discovered faint filaments in the south, like the much brighter ones along the northwest limb, delineate the primary shock as it propagates into the interstellar medium. In the northwest, a narrow X-ray peak traces just inside the crisp optical filaments and provides a laboratory for observing the effects of a fast, nonradiative shock propagating nearly perpendicular to our line of sight. The calculated profile of the thermal X-ray emission from a rapidly ionizing postshock plasma closely matches the observed profile, supporting a model in which nonequilibrium thermal processes dominate the X-ray emission in the northwest. The measured displacement of 8'' between the optical filaments and the X-ray peak, combined with previously measured proper motions for the filaments, indicates a timescale of only ~120 yr for X-ray heating and ionization behind the shock. In addition to the narrow optical filaments around the rim of SN 1006, we find faint, diffuse Hα emission within the remnant shell to the southwest. This emission probably represents nonradiative sheets viewed obliquely.

The discovery of Balmer-Filaments Encercling SNR RCW 86

view Abstract Citations (45) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The discovery of Balmer-Filaments Encercling SNR RCW 86 Smith, R. Chris Abstract We report the discovery of Balmer-dominated filaments along almost the complete periphery of the supernova remnant RCW 86 (also known as G 315.2-2.3 or MSH 14-63). Using the UM/CTIO Curtis Schmidt telescope, we obtained deep CCD images in the emission of Hα and [S iii, together with continuum images to remove stellar confusion. After continuum subtraction, we discovered a network of Hα filaments reaching almost completely around the remnant. Most of the newly identified filaments show no corresponding [S ii] emission, indicating that they belong to the peculiar "Balmer-dominated" class of filaments. Comparison of these Balmer filaments with existing radio and X-ray images of RCW 86 shows an overall similarity, although interesting differences are apparent upon detailed inspection. While further observations of these newly identified optical filaments may eventually provide more detailed information on the kinematics and distance to RCW 86, the distance currently remains uncertain. We argue that the shorter distance estimates of ∼1 kpc are still favored. Publication: The Astronomical Journal Pub Date: December 1997 DOI: 10.1086/118676 Bibcode: 1997AJ....114.2664S Keywords: SUPERNOVA REMNANTS; X-RAYS: ISM full text sources ADS | data products SIMBAD (4)

Amalgamation of interacting light beamlets in Kerr-type media

The interaction of optical filaments in bulk self-focusing media is investigated theoretically and numerically. The nature of this interaction is shown to vary with the incident individual powers and relative phases of the beamlets. By means of virial arguments supported by numerical results it is found that three distinct evolution regimes characterize two in-phase interacting filaments: (i) When each filament has a power below Nc/4, where Nc is the critical self-focusing threshold for a single wave, both filaments disperse along their propagation axis. (ii) When their respective powers lie between Nc/4 and Nc, they fuse into a single central lobe that may self-focus until collapse, depending on their initial separation distance. The critical distance below which a central lobe forms and collapses is estimated analytically. (iii) When their incident powers both exceed Nc, initially separated filaments individually self-focus without mutual interaction. In contrast to in-phase beamlets, two light cells with opposite phase are shown to never coalesce. The extension of the self-focusing dynamics to optical filaments in bulk media with anomalous group-velocity dispersion is discussed.

Radio observations of the X-ray supernova remnant G272.2– 3.2

Radio continuum observations are presented for the recently discovered X-ray supernova remnant (SNR) G272.2 - 3.2. Radio emission from this SNR has never before been detected. We find this remnant to have a non-thermal radio spectral index of 0.55 ± 0.15 (S ∝ λ), and an almost circular appearance with a diameter of approximately 15 arcmin (in agreement with the X-ray size). High-resolution observations with the Australia Telescope Compact Array (ATCA) reveal the remnant to consist of a series of faint filaments and patches of emission, with a maximum surface brightness of 10 mJy beam area at 1.4 GHz, and a diffuse emisson component. This diffuse emission appears to be produced by shock-accelerated electrons. Modest spectral index variations are seen across the SNR, indicating that G272.2 - 3.2 contains no significant thermal or plerionic component. Optical filaments in the region appear to align well with the radio 'blobs', whilst the X-ray enhancements show no correlation with the 'blobs'. These correlations are consistent with a somewhat higher age for the remnant than is derived from the X-ray data; perhaps 6 × 10 yr or so. Within the sensitivity of the observations no polarized emission was detected from G272.2 - 3.2, which is possibly indicative of a highly twisted magnetic field.

All Quiet on the Western Front? X-Ray and Optical Observations of a Prototypical Cloud--Blast Wave Interaction in the Cygnus Loop

We use the ROSAT High Resolution Imager and deep, wide-field, optical images to study a section of the western edge of the Cygnus Loop. Fast, radiative shocks result in a network of bright optical filaments. The most prominent X-rays are associated with and interior to these optical filaments. This X-ray enhancement is due to additional compression of hot, postshock gas by a reflected shock, which formed when the blast wave encountered a large molecular cloud in this region about 10<SUP>3</SUP> yr ago. This cloud is traced by far-infrared dust and CO emission that are concentrated toward the exterior of the bright filaments and extended both along the line of sight and roughly north-south in the plane of the sky. Farther west, a curved Balmer-dominated filament marks the edge of the blast wave, which has begun to wrap around the intervening cloud. The region is seen close to edge on, and this simple geometry enables us to determine its physical structure in detail: this is an example of the early stage of a cloud- blast wave interaction. Because the cloud is large, the lifetime of the interaction is long compared with the timescale over which the blast-wave properties (such as pressure) change, so evolution of the shock during the interaction is important. Bright optical filaments, associated limb-brightened X-rays, and fainter Balmer-dominated emission on the exterior of the remnant are all common around the rim of the Cygnus Loop. These phenomena are the result of interaction of the supernova blast wave with large clouds. The western edge is the prototypical example of the physical processes occurring throughout this supernova remnant.

THE DYNAMICS OF LARGE-SCALE WINDS IN NEARBY STARBURST GALAXIES

ABSTRACT I present detailed imaging Fabry-Perot spectrophotometric observations of the nearby prototype starburst galaxy M82, in order to study the high-velocity outflows observed in such galaxies as a property of the energetic starburst phenomena associated with their nuclei. The high spatial and kinematic resolution of our observations has} allowed us to perform photometric analysis of H-alpha, [N II] and [O III] spectral lines at roughly one hundred thousand positions across the extent of the galaxy. Additional model constraints are provided by broadband and narrowband optical imagery, optical spectropolarimetry, and ROSAT soft x-ray imagery. The observed kinematics of the H-alpha-emitting gas in M82 suggest a bipolar outflow of material along the minor axis at a projected velocity of ~300 km s-1, fueled by the bright nuclear starburst regions in the galaxy's disk. All three spectral lines show double components in the centers of the outflowing lobes, with the H-alpha line split by ~300 km s-1 over a region almost a kiloparsec in size. We argue for a model in which the optical emission is radiated by denser ambient material on the surface of "bubbles" that have been evacuated by a hot wind (~108 K) visible at x-ray wavelengths. Comparison of Monte-Carlo simulations with the observed H-alpha and [N II] kinematics shows that the outflow is confined to a cylinder within 350~pc of the disk, flaring outward in a cone beyond that point. The inner optical line-emitting filaments consist primarily of gas that has been entrained from the disk by the outflow, although ambient material in the halo of M82 may be excited by shocks in the outflow at larger radii. The detailed morphology of the bubbles is complex, but the kinematic structure, bubble geometry, and emission line strengths confirm the major predictions of galactic wind hydrodynamical simulations. A spherical halo around M82 is also observed in emission lines. Intermediate [N II]/H-alpha values and spectropolarimetry observations suggest that this halo emission is not intrinsic, but rather disk radiation that has been scattered by a large spherical distribution of dust. Recent large-scale H I maps show massive streamers of atomic gas connecting M81 and M82--residue of a past interaction. We suggest that the dusty halo of M82 may be associated with this H I gas distribution. A remarkably low [N II]/H-alpha ratio is seen in the region of the outflow, implying that the radiation from the surface of the wind bubbles may be produced, in large part, via photoionization of the gas by the nuclear starburst. A corresponding increase in the [O III]/H-alpha ratio along the outflow is also observed. Nevertheless, the importance of shocks as an excitation mechanism is clear in the detailed spatial correlation of the optical and ROSAT soft x-ray emission, particularly at larger radii. Funding for this research has been provided by the office of the Dean of Natural Sciences at Rice University, the Texas Space Grant Consortium, and the Sigma Xi Research Society. Additional funding was provided by AURA/ STScI (grant GO-4382.01.92A), the National Science Foundation (grant AST 88-18900), the William F. Marlar Foundation, the National Optical Astronomy Observatories (NOAO), and Mr. and Mrs. William Gordon.

Polarized radio filaments in the Vela X supernova remnant

The radio-bright Vela X component of the Vela supernova remnant (SNR) was mapped in total intensity and in polarization at 8.4 GHz with 3-arcmin resolution. Prominent filamentary structure (unrelated to the optical filaments) is seen in the polarization image and to a lesser extent in total intensity. The filaments are highly polarized, with magnetic fields directed along the filaments. They have moderate Faraday rotation (mean RM ~ 44 rad m–2) and the little depolarization. Comparison with data at 5 and 2.7 GHz suggests that the overall spectral index is typical of a SNR and relatively uniform throughout the region.

Optical and Radio Emission from the Galactic Supernova Remnant HB 3(G132.6 +1.5)

view Abstract Citations (19) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optical and Radio Emission from the Galactic Supernova Remnant HB 3(G132.6 +1.5) Fesen, Robert A. ; Downes, Ronald A. ; Wallace, Debra ; Normandeau, Magdalen Abstract Wide-field Hα images of the galactic supernova remnant RB 3 are presented and compared to new DRAO radio continuum maps at 408 and 1420 MHz with angular resolutions of 3.5' × 4.O' and 1.0' × 1.13', respectively. RB 3's optical emission appears as a broken shell of filamentary and diffuse emission, most incomplete along the northern rim. New optical filaments are detected along the remnant's southern radio boundary, in an area of suspected greater extinction due to a foreground molecular emission ridge. An optical spectrum of bright, western limb filaments indicates a shock velocity ≤100 km s-1, a [S II] λ6716/λ6731 derived electron density of ≤150 cm-3, and an E(B - V) = 0.71±0.04 consistent with x-ray derived column density estimates. The remnant's radio spectral index is - 0.64±0.01, evaluated in regions away from confusing emission from W3. RB 3's scalloped western structure suggests multiple shock fronts, possibly related to the remnant's large size and late evolutionary stage, where the remnant's shock is expanding into density irregularities in the local interstellar medium. Overall, we find a strong correlation between individual radio and optical emission features at both large and small spatial scales. We suggest that a strong radio-optical correlation plus a multishell structure may be better indicators of advanced remnant age than the often mentioned diffuse optical morphology. Publication: The Astronomical Journal Pub Date: December 1995 DOI: 10.1086/117736 Bibcode: 1995AJ....110.2876F Keywords: SUPERNOVA REMNANTS; ISM: INDIVIDUAL: HB 3(G132.6+1.5) full text sources ADS | data products SIMBAD (6)