Interference Filter Photographs Research Articles

Deep Narrow Band Interference Filter Photographs of Selected Extended Planetary Nebulae

Narrow-band interference filter photographs in the light of Hα, [S II] (λ = 6717 and 6731 A). [N II] (λ = 6584 A) and [O III] (λ = 4363 A) of four extended PNs are shown. These photographs were obtained with a focal reducer and a single-stage image tube attached to the 2.1 m Cassegrain focus telescope of the Observatorio Astronómico Nacional at San Pedro Mártir, B.C.N. The exposure times were of one hour. For each photograph we have obtained a calibration by means of a step density wedge.

SEVEN NEW PLANETARY NEBULAE IN THE DIRECTION OF BAADE'S WINDOW.

ABSTRACT The authors present seven new planetary nebula candidates that were discovered with interference-filter photographs, and that lie in or near Baade's Window (l = 1°.0, b = -3°.9). Two of them are angularly resolved, and are probably relatively nearby disk objects. All are faint and suffer from high interstellar reddening.

The normal fundus VI

In 185 clinically healthy subjects ranging in age from 10 to 71 years with apparently normal ophthalmoscopy, colour and interference filter photographs of the one eye revealed one or more distinctly outlined yellowish elements in 126 eyes (68%) and a single red spot in 3 eyes (2%). The frequency of eyes with one or more fundus elements correlated positively (P less than 0.01) with age and predominated in males with an age greater than or equal to 25 years. A thinning of the pigment epithelium in the posterior pole of the fundus without concomitant myopia was associated (P less than 0.01) to the age group above 50 years (19 of 22 eyes) compared with the age group below 50 years (3 of 12 eyes). The fundus elements seen in 126 of 162 colour photographs with corresponding interference filter photographs of sufficient quality were recognized with the green filter in 98%, with the blue filter in 91% and the red filter photographs in 61% of the eyes.

The normal fundus fluorescein angiogram II

Three consecutive photographic fundus examinations using colour, interference filter photographs and fluorescein angiography showed no intraindividual variation within one year, but a considerable interindividual variation of the morphologic fundus elements was found in 48 eyes of 48 clinically healthy middle aged subjects. There were 20 eyes with distinctly outlined minute hyperfluorescent elements, 15 eyes with minute indistinctly outlined and 3 eyes with distinctly outlined hypofluorescent elements. These elements remained unchanged after one year. In 80% of the eyes with hypofluorescent elements there were characteristically no concomitant hyperfluorescent elements. Seventeen of 48 eyes had fundus elements exclusively visible in the colour and filter pictures. Most hyperfluorescent elements corresponded with elements in the green interference filter photographs (85% of the eyes). These findings indicate minute changes in the layers of Bruch's membrane and the retinal pigment epithelium in most of the eyes. The indistinctly outlined hypofluorescent elements might represent minute choroidal vascular filling defects or minute areas with blockage of the choroidal fluorescence.

An optical investigation of the peculiar supernova remnant CTB 80

view Abstract Citations (42) References (56) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An optical investigation of the peculiar supernova remnant CTB 80. Blair, W. P. ; Fesen, R. A. ; Rull, T. R. ; Kirshner, R. P. Abstract Interference-filter photographs and optical spectrophotometry are used to investigate the optical emission associated with the peculiar supernova remnant CTB 80. Optically, the remnant consists of outlying diffuse and filamentary emission surrounding a small, central ring of filaments which are coincident with the central radio emission peak. Spectra of two filaments in the southwestern part of the remnant show strong forbidden S II emission relative to H-alpha; in conjunction with the nonthermal radio emission in this region, this suggests that the filaments are shock heated. Filaments outside the radio structure in the northeast show a similar optical spectrum and may also be a part of CTB 80. The central filaments form a well-defined shell structure in the light of forbidden O III emission 5007 A but are irregular in H-alpha showing both knots and diffuse emission. Publication: The Astrophysical Journal Pub Date: July 1984 DOI: 10.1086/162187 Bibcode: 1984ApJ...282..161B Keywords: Astronomical Spectroscopy; Supernova Remnants; Astronomical Photography; Chronology; H Alpha Line; Nonthermal Radiation; Radio Astronomy; Spectrophotometry; Astronomy full text sources ADS | data products SIMBAD (2)

THE PARABOLIC-SHAPED NEBULA AROUND LSS 3027.

ABSTRACT A parabolic nebula centered on the OB- star LSS 3027 is identified. New spectroscopic and photometric data of the star suggest a spectral type of B2 V. The broad-band filter and interference filter photographs of the nebula indicate that the star LSS 3027 has a small H II region enveloped by a reflection nebula that appears parabola shaped on the broad-band blue photographs. The radius of the H II region is about 0.16 pc, and the electron density is about 70 cm-3.

Spectrophotometry of the Cygnus Loop

view Abstract Citations (127) References (55) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometry of the Cygnus Loop Fesen, R. A. ; Blair, W. P. ; Kirshner, R. P. Abstract New spectrophotometry for 17 filaments in the Cygnus Loop are presented. A wide variety of spectral properties is observed within the remnant. Comparisons with published shock models indicate significant differences between the models and observations with the range of observed line intensities not well described by models with varying shock velocity. Interference-filter photographs of the remnant's northeastern, northwestern, and western nebulae in H-alpha + N II, S II, O III, and O I show radial variations of line emission intensity with a scale much larger than that expected from a shock moving through a uniform medium. It is suggested that the emission variations and apparent ionization structure are the result of the shock front encountering an inhomogeneous interstellar medium. Publication: The Astrophysical Journal Pub Date: November 1982 DOI: 10.1086/160408 Bibcode: 1982ApJ...262..171F Keywords: Cygnus Constellation; Nebulae; Stellar Spectrophotometry; Supernova Remnants; Balmer Series; Electron Density (Concentration); Electron Energy; Emission Spectra; High Resolution; Hydrogen; Interstellar Matter; Line Spectra; Shock Waves; Astrophysics full text sources ADS |

Galactic ring nebulae associated with Wolf-Rayet stars. VI - NGC 3199, anon /MR 26/, RCW 58, and RCW 104

We have obtained narrow-band interference filter photographs and high resolution Fabry-Perot spectra for four galactic ring nebulae associated with Wolf-Rayet stars: NGC 3199, anon (MR 26), RCW 58, and RCW 104. All of these four nebulae show interaction between the stellar wind and the ambient interstellar medium. NGC 3199, anon (MR 26), and RCW 104 are classified as W-type nebulae. RCW 58, having a prominent ring of stellar ejecta, is classified as an E-type nebula. For most W-type nebulae, the kinetic energy in the shell is only about 1% of the total mechanical energy input from the stellar wind, while the ratio of the shell momentum to the total momentum injected by the stellar wind is about 0.5 and apparently increases with the nebular age.

Galactic ring nebulae associated with Wolf-Rayet stars. VII - The nebula G2.4 plus 1.4

view Abstract Citations (25) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Galactic ring nebulae associated with Wolf-rayet stars. VII. The nebula G 2.4 +1.4. Treffers, R. R. ; Chu, Y. -H. Abstract Narrow band interference filter photographs and Fabry-Perot spectra are presented for the nebula G2.4 plus 1.4. In H-alpha and forbidden O III at 5007 A, the nebula shows a complex double shell structure, which appears quite different in forbidden N II at 6583 A and forbidden S II at 6732 A. The Fabry-Perot spectra show components with velocities V(LSR) between minus 20 and plus 25 km/sec. It is concluded that G2.4 plus 1.4 is a supernova remnant near the galactic center that is illuminated by the peculiar WC star LSS 4368. Publication: The Astrophysical Journal Pub Date: March 1982 DOI: 10.1086/159715 Bibcode: 1982ApJ...254..132T Keywords: Astronomical Photography; Nebulae; Stellar Spectra; Supernova Remnants; Wolf-Rayet Stars; H Alpha Line; Nitrogen; Oxygen; Astronomy full text sources ADS | data products SIMBAD (1) Related Materials (7) Part 1: 1981ApJ...249..195C Part 2: 1981ApJ...249..586C Part 3: 1981ApJ...250..615C Part 4: 1982ApJ...254..562C Part 5: 1982ApJ...254..569T Part 6: 1982ApJ...254..578C Part 8: 1983ApJS...53..937C

The Planetary Nebula in the Galactic Cluster NGC 2818

The planetary nebula PK 261+8°1 is of special interest due to its apparent physical association with the galactic cluster NGC 2818 (Tiff, Connally, and Webb 1972, M.N.R.A.S., 158, 47). During 1975–76 we obtained spectrophotometric observations (both photographic and photoelectric) and interference filter photographs (Hβ, [OIII], [NII], and [SII]) of this object at Cerro Tololo. The nebula has a rather smooth bilaterally symmetric “hourglass” structure in the Hβ and [OlII] photographs, while several bright filaments appear in [NII] and [SII]. The spectrum of PK 261+8°1 is very rich in lines characteristic of both low ionization ([OI], [OII], [NI], [NII], [SII]) and high ionization (He II, [OIII], [NeV]) regions. Using the photo electric observations, we derive Te = 14,500 ± 1500°K from the [Olli] lines and Te = 11,000 ± 1300°K from the [OIII] lines and Te = 11,000 ± 1300°K from the [NII] lines. The λ6717/λ6730 [SII] ratio suggests that Ne ≤ 800 cm−3 in the regions where S+ exists. Additional information μ the density and temperature structure of the nebula derived from the deep photographic spectra will also be presented. Due to the complicated ionization structure, an accurate abundance analysis of PK 261+8°1 is difficult. Consequently, we will present the quantitative results from a variety of abundance calculation techniques. We conclude that He/H = 0.14 ± 0.01, N is substantially enriched relative to H and 0 (N/H ≥ 0/H = 4 × 10−4), while the abundances of 0, Ne, S, Ar, and Cl relative to H are similar to values typical of galactic planetary nebulae. Other characteristics of the nebula derived from its association with the cluster NGC 2818 and its spectral similarity to Henize 97 in the Large Magellanic Cloud will be discussed. This research was supported in part by a grant from the Research Corporation.

Detection of molecular hydrogen emission from five planetary nebulae

view Abstract Citations (116) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of molecular hydrogen emission from five planetary nebulae. Beckwith, S. ; Persson, S. E. ; Gatley, I. Abstract The v = 1 to 0 S(1) line of molecular hydrogen has been detected in five planetary nebulae. They are the Ring Nebula (M57, NGC 6720), BD+30 deg 3639, Hb 12, CRL 618, and CRL 2688. A region in the northeast of the Ring Nebula has been mapped in both the v = 1 to 0 S(1) molecular hydrogen line and the Brackett gamma line of atomic hydrogen. The H2 emission is not spatially correlated with the B-gamma, but is correlated with the (OI) emission as determined from interference filter photographs. Publication: The Astrophysical Journal Pub Date: January 1978 DOI: 10.1086/182601 Bibcode: 1978ApJ...219L..33B Keywords: Astronomical Spectroscopy; Emission Spectra; Hydrogen; Planetary Nebulae; Astronomical Maps; Brightness Temperature; H Gamma Line; Hydrogen Atoms; Astronomy; Molecular Hydrogen:Planetary Nebulae full text sources ADS | data products SIMBAD (10)

The complex outer shell of eta Car.

Short-exposure, interference-filter photographs obtained at the prime focus of the CTIO 4 meter reflector reveal the great complexity and extent of eta Carinae's outer shell. Some features have increased their distances from the central object with respect to Thackeray's photographs of a quarter-century ago, and some apparent structural relationships are found between features of the homunculus and the outer shell. A speculative relationship to van den Bergh's quasi-stationary flocculi in Cas A is pointed out. (AIP)

Optical and millimeter-wave observations of the M8 region

view Abstract Citations (81) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optical and millimeter-wave observations of the M8 region. Lada, C. J. ; Gull, T. R. ; Gottlieb, C. A. ; Gottlieb, E. W. Abstract Millimeter-wave observations made toward the NGC 6530-M8 star-forming complex are compared with high-quality optical interference-filter photographs of that region. Extensive CO observations reveal a large molecular cloud in this direction, within which three bright spots of CO emission are found. Two bright spots are associated in angle with prominent optical features. One of these is coincident with the star Herschel 36 and the Hourglass Nebula; the second appears coincident in angle with an ionization front southeast of Herschel 36. The kinematics of the molecular cloud is studied. The radial velocity of CO emission is found to vary smoothly across the cloud, but it is difficult to interpret this in terms of coherent mass motion of the entire cloud. Analyses of CO, radio-continuum, and optical data indicate that Herschel 36 is the most likely ionizing source for most of the M8 II region. Comparison of optical and radio observations suggests a geometrical model for the region, which places the H II region at the front edge of the molecular cloud. Further considerations indicate that the M8 molecular cloud, the M8 H II region, the young cluster NGC 6530, and the Sgr OB1 association appear to be related in a geometrical evolutionary sequence with cloud evolution, and possibly star formation, proceeding inward with time from the position of the foreground star cluster to the position of the molecular cloud. Publication: The Astrophysical Journal Pub Date: January 1976 DOI: 10.1086/154058 Bibcode: 1976ApJ...203..159L Keywords: Carbon Monoxide; Interstellar Matter; Light Emission; Millimeter Waves; Nebulae; Radio Astronomy; Absorption Spectra; Brightness Temperature; Emission Spectra; H Ii Regions; Infrared Radiation; Radial Velocity; Radiation Sources; Astronomy full text sources ADS | data products SIMBAD (16)

Forbidden Sulfur {\sc II} Structures in Carina Nebula

S ii and O iii interference-filter photographs of the northern part of the Carina Nebula, obtained at the prime focus of the CTIO 4-meter reflector, are presented. Many of the principal features of each are absent in the other. The most prominent feature in the light of S ii is the curious ring associated with the radio source Carina II, which shows intricate filamentary structure. Also conspicuous are three small clouds associated with dust, one of them spiral in shape, which glow brightly in S ii but are invisible in O iii. (AIP)

Observations of Mass Motions in Markarian 78 . .

Spectroscopic observations are presented showing the presence of emitting clouds in the inner regions of Markarian 78. These clouds are similar to the "nuclear clouds" found by Walker in the Seyfert galaxies NGC 1068 and NGC 4151. Interference-filter photographs are also presented showing Markarian 78 to be enveloped in a network of filaments similar to those seen in exploding" galaxies. An attempt is made to understand the outlying filaments as remnants of a previous explosion ionized by nonthermal radiation from the nucleus. Subject headings: galaxies, individual - galaxies, motions in - Seyfert galaxies

Resonance radiation in artificial strontium clouds

Abstract We have considered the problem of the resonance scattering of sunlight by a spherically symmetric, optically thick gas cloud. Theoretical isophotes, line profiles, and irradiances are computed by using a two-level atomic model, but the multiple scattering is taken rigorously into account. An integral equation is derived for N 2 ( r ) , the number density of excited atoms at the point r, which is solved by iteration. It is then possible to find the complete intensity field by direct integration. Line profiles and line strengths for the emergent radiation can be readily calculated. The results of the calculations are compared with photometric data obtained by the Los Alamos Scientific Laboratory (LASL) from the barium-strontium release of the DOGWOOD event in the ARPA-sponsored SECEDE I series (Puerto Rico, May 1968). The main emphasis is placed on interpreting interference-filter photographs taken in the SrI resonance line λ4607 A, and displayed in isophote form. Comparisons of the observed and calculated isophotes, and to a lesser extent the irradiances, enable values for the physical parameters to be assigned to the clouds, namely, the optical radius, the Gaussian radius, the central number density, the total number of SrI atoms, and the molecular diffusion constant for strontium in air.