Blue Lobe Research Articles

The circumstellar environment of IRAS 05338-0624.

Millimeter continuum and spectral line observations with 10", 30", and 60" resolution are used to characterize the structure and chemistry of the gas around the young, embedded star, IRAS 05338-0624. On arcminute scales, emission from dense gas tracers outline an isolated condensation centered on the IRAS source position. The condensation is characterized by a size of approximately 60", a density of 2 x 10(5) cm-3, and a virial mass of 40 M solar. Interferometric CS J = 2-1 observations show two peaks, one toward the continuum peak and the other toward a position 14" west and 8" south. Single-dish maps of SO, CH3OH, and SiO show pronounced wing emission to the west of the IRAS source, which interferometer observations reveal to be a compact region of outflow activity. CS emission as redshifted and blueshifted velocities reveals a bipolar outflow oriented with a position angle of 45 degrees, while SiO emission appears to be tracing a fast shock interaction region at the CS red-lobe peak, 14" west and 8" south of the IRAS source. Finally, H13CO+ emission traces clumps of quiescent gas toward the IRAS source and adjacent to the blue lobe of the outflow. Column densities and molecular fractional abundances are derived to explore the interaction between the surrounding condensation and the young stellar object. We find evidence for gas phase depletions within the overall condensation in several gas tracers (CO, CS, HCN, SO) but not in the region immediately around the young stellar object. Enhanced abundances of SO, CH3OH, and SiO (by factors of 4, >100, >1000, respectively) are observed in the shocked gas; these enhancements may be explained in terms of a nondissociative shock liberating mantle materials that contain some amount of refractory materials, a moderate velocity dissociative shock in which only minor sputtering of Si occurs, or a shock that impacts surrounding material with a range of speeds.

Nonlinear interaction of optical biharmonics in a gaseous medium without inversion centers

This study investigates observed interactions between second-order optical biharmonics with difference frequencies characteristic of intra-molecular spin motion. The simultaneous solutions of equations of motion for electron shells and nuclear and generalized Maxwell equations for electromagnetic waves are found. It is shown that a complete orthogonal series of solutions for the observed condition are comprised of Bessel Jn(z) functions. Leading from the properties of these functions it can be proved that bimodal light at a distance L gives rise, for example, to red and blue side lobes κL of comparable intensities. The results obtained may be useful in finding and developing low energy methods for destroying inversion symmetry in gaseous media.

Detection of Magnetohydrodynamic Shocks in the L1551 Outflow

AbstractWe report the results of CO J=l—+0 mapping of portions of the blue outflow lobe of L1551 with ~ 7” (N-S) × 4” (E-W) resolution, obtained with the 3-element OVRO millimeter array. Comparison of our interferometer mosaic with lower resolution single-dish data shows that we resolve the strongest single-dish emission regions into filamentary structures, such as are characteristic of shock fronts mapped via their near-infrared H2 emission in other outflow sources.

Molecular Cloud Core and CS Outflow Associated with Haro 4-255 FIR

view Abstract Citations (8) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular Cloud Core and CS Outflow Associated with Haro 4-255 FIR Tatematsu, Ken'ichi ; Umemoto, Tomofumi ; Murata, Yasuhiro ; Chen, Hua ; Hirano, Naomi ; Takaba, Hiroshi Abstract The region containing the two young stellar objects, Haro 4-255 and Haro 4-255 FIR, has been studied through single-dish and aperture-synthesis CS (1-0) observations. We have detected an intense CS outflow, whose FWZI velocity extent is about 9 km s-1, in the single-dish observations. The distribution of the blue CS lobe is appreciably different from that of the blue CO lobe, whereas the distribution of the red CS lobe is similar to that of the red CO lobe. The CS abundance in this outflow seems to be enhanced nearly by one order of magnitude, although that in the quiescent gas shows a more normal value. The mass of the CS outflow is appreciably larger than that of the CO outflow, while the mechanical luminosity of the CS outflow is smaller than that of the CO outflow. The aperture-synthesis data show no counterpart to the CS outflow but contain two emission features which correspond to two local intensity maxima seen in the single-dish map. One of these features extends from Haro 4-255 to Haro 4-255 FIR: it might represent a density maximum in the molecular cloud core. The blueshifted emission of the CS outflow is less prominent, probably because it is impeded by the densest portion of the core. Publication: The Astrophysical Journal Pub Date: December 1993 DOI: 10.1086/173525 Bibcode: 1993ApJ...419..746T Keywords: ISM: CLOUDS; ISM: INDIVIDUAL NAME: HARO 4-255 FIR; ISM: MOLECULES; ISM: JETS AND OUTFLOWS; STARS: PRE-MAIN-SEQUENCE full text sources ADS | data products SIMBAD (5)

A Well-shaped Bipolar Outflow Shell in Monoceros R2

We report in this Letter some results of a study of the massive bipolar outflow in the central region of the giant molecular cloud Monoceros R2. We find in our CO J=1-0 maps an eggplant-shaped, thin bipolar outflow shell that outlines the extended blue lobe of the bipolar outflow. The projected length and width of the shell are about 5.3 and 2.7 pc, respectively, and the averaged projected thickness of the shell is ∼0.3 pc. The outflow shell's symmetry axis is inclined by ∼70° with respect to the line of sight. We make a quantitative comparison of our results with the Shu et al. outflow model incorporating a radially directed wind and find that this simple model naturally explains the shape of the observed shell

Detection of magnetohydrodynamic shocks in the L1551 outflow

We report the results of CO J=1→0 mapping of portions of the blue outflow lobe of L 1551 with ∼7″ (N-S)×4″ (E-W) resolution, obtained with the three-element OVRO millimeter array. Comparison of our interferometer mosaic with lower resolution single-dish data shows that we resolve the strongest single-dish emission regions into filamentary structures, such as are characteristic of shock fronts mapped via their near-infrared H 2 emission in other outflow sources. We detect a continuous velocity gradient across the brightest filamentary structure in our maps. The projected, deconvolved, FWHM of this feature is 1-2×10 16 cm, similar to that predicted in theoretical models of C-shocks

Blue lobe galaxies in the cooling flow clusters Abell 1795 and Abell 2597

view Abstract Citations (74) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Blue Lobe Galaxies in the Cooling Flow Clusters Abell 1795 and Abell 2597 McNamara, Brian R. ; O'Connell, Robert W. Abstract We present CCD color imagery for the centrally dominant galaxies in the clusters A1795 and A2597. These objects, which reside at the centers of large cluster cooling flows, have unusually blue central colors, spatially extended emission-line structures, and strong radio sources. Using difference images formed by modeling and subtracting the background galaxy from our U-band and Stromgren b-band images, we find prominent lobelike continuum structures in their central 10-20 kpc. In addition, we find absorption features which can be plausibly attributed to dust. Using U-I color maps, we show that the continuum lobes are very blue and occur on or near bright radio-source structures. If the blue lobes are due to young stars, this spatial correlation suggests that an interaction between the radio sources and the ambient gaseous intracluster medium may have induced the star formation. If this is a common phenomenon in cluster cooling flows, it could help to explain the scatter in the correlations between color and mass-accretion rate. It may also help explain why blue color anomalies in cluster cooling flows occur preferentially in the inner 5-20 kpc similar to the size scales of their radio-source structures. Other interpretations for the color structure include the blue debris from recent mergers or scattered nonthermal radiation from an active nucleus. The color and radio properties of these objects are qualitatively similar but smaller in luminosity and spatial extent to those found in high redshift radio galaxies. The physical mechanism(s) responsible for the lobe structures in A1795 and A2591 may be relevant to understanding "the alignment effect" found in high redshift radio galaxies. Publication: The Astronomical Journal Pub Date: February 1993 DOI: 10.1086/116440 Bibcode: 1993AJ....105..417M Keywords: Charge Coupled Devices; Cooling Flows (Astrophysics); Galactic Clusters; Galactic Structure; Imaging Techniques; Early Stars; Intergalactic Media; Radio Sources (Astronomy); Star Formation; Astrophysics; COOLING FLOWS; GALAXIES: INTERACTIONS; GALAXIES: CLUSTERING full text sources ADS | data products NED (4) SIMBAD (3)

The outflow in the L1157 dark cloud - Evidence for shock heating of the interacting gas

view Abstract Citations (95) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Outflow in the L1157 Dark Cloud: Evidence for Shock Heating of the Interacting Gas Umemoto, T. ; Iwata, T. ; Fukui, Y. ; Mikami, H. ; Yamamoto, S. ; Kameya, O. ; Hirano, N. Abstract In the L1157 dark cloud, a well-collimated bipolar CO outflow associated with a cold IRAS source 20386 + 6751 was discovered. The gas temperature toward the blue lobe of the outflow rises to about 30 K from the temperature of the surrounding gas (not greater than 10 K); this high temperature region is very localized within the blue lobe. The HCO(+), HCN, and NH3 lines show blueshifted and broad-line profiles toward the blue CO lobe. Furthermore, their distributions are similar to that of the blue lobe. Analysis of the energy of the outflow and dense gas suggests that a strong shock caused by the outflow is responsible for the temperature enhancement. Such shock heating has rarely been observed in low-mass star-forming regions. These data show that the outflow has an influence on the thermal properties of the parent cloud at least locally through shock processes in its early evolutionary stage. Publication: The Astrophysical Journal Pub Date: June 1992 DOI: 10.1086/186431 Bibcode: 1992ApJ...392L..83U Keywords: Gas Flow; Infrared Astronomy Satellite; Interstellar Matter; Shock Wave Interaction; Star Formation; Stellar Composition; Ammonia; Carbon Monoxide; Formyl Ions; Hydrocyanic Acid; Shock Heating; Astrophysics; ISM: MOLECULES; ISM: INDIVIDUAL ALPHANUMERIC: L1157; ISM: JETS AND OUTFLOWS; STARS: FORMATION; SHOCK WAVES full text sources ADS | data products SIMBAD (2)

Detection of SiO emission in the L1157 dark cloud

view Abstract Citations (104) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of SiO Emission in the L1157 Dark Cloud Mikami, Hitomi ; Umemoto, Tomofumi ; Yamamoto, Satoshi ; Saito, Shuji Abstract Intense thermal emission lines of SiO (v = 0, J = 1-0 and 2-1) are detected in a low-mass star-forming region, L1157. The emission is confined to a compact region toward the blue lobe of the CO outflow, where shock heating due to interaction between the outflow and dense gas has been found. In contrast, the emission of SiO is not detected toward the IRAS source and the red lobe. The distribution of SiO is different from that of CS; the intense CS line is observed in the vicinity of the IRAS source. The peak fractional abundance of SiO is estimated to be about 10 exp -7. This value is higher than a typical upper limit in quiescent dark clouds by a factor of about 10,000. These results suggest that SiO is produced in the shocked region probably through grain destruction processes. Publication: The Astrophysical Journal Pub Date: June 1992 DOI: 10.1086/186432 Bibcode: 1992ApJ...392L..87M Keywords: Emission Spectra; Infrared Astronomy Satellite; Interstellar Matter; Molecular Clouds; Silicon Oxides; Star Formation; Stellar Evolution; Stellar Mass; Astrophysics; ISM: ABUNDANCES; ISM: MOLECULES; STARS: FORMATION; SHOCK WAVES full text sources ADS | data products SIMBAD (9)

U-shaped outflow in the LYNDS 1221 dark cloud - an example of interaction of outflows with ambient molecular clouds

Molecular line observations of the dark cloud L1221 in the J = 1-0 transitions of CO, 13 CO, C 18 O, HCO + , HCN, and CS with angular resolutions of 17″-2.7' are presented. A bipolar CO outflow associated with IRAS 22266+6845 have been discovered. The outflow shows a remarkably bent U-shaped structure. The present observations show rather clear evidence for interaction of the outflow with the ambient molecular gas; the ambient gas shows density depression and velocity shift just toward the blue lobe of the outflow. This fact indicates the acceleration and exclusion of the ambient gas by the outflow.

A very straight and collimated outflow in the core of OMC-1

We have recently discovered a large-scale (200″) outflow system in the core of OMC-1 (fig. 1), centered about 100″ South of IRc2 and extending over some 120″ (red lobe) resp. 60″ (blue) along a position angle of —31° (Schmid-Burgk et al. 1990). The blue lobe which might actually protrude into the HII region M42 is poorly defined in CO 2-1, but the red lobe reveals a number of remarkable properties which we summarize here:The outflow is very straight and smooth. Over the full length of 120″, the center of any cross scan deviates by not more than about 1″ from a straight line. This line passes to within 2″ the peak of the submm source FIR4 of OMC-1 (Mezger, Wink and Zylka 1990) and the mm continuum peak CS3 (Mundy et al. 1986); it also cuts across the red and blue SiO-outflow lobes recently discovered some 5-10″ to either side of FIR4 (Ziurys, Wilson and Mauersberger 1990). It thus seems that the “base” of our large-scale CO jet can be seen as well.

A very straight and collimated outflow in the core of OMC-1

We have recently discovered a large-scale (200″) outflow system in the core of OMC-1 (fig. 1), centered about 100″ South of IRc2 and extending over some 120″ (red lobe) resp. 60″ (blue) along a position angle of —31° (Schmid-Burgk et al. 1990). The blue lobe which might actually protrude into the HII region M42 is poorly defined in CO 2-1, but the red lobe reveals a number of remarkable properties which we summarize here:The outflow is very straight and smooth. Over the full length of 120″, the center of any cross scan deviates by not more than about 1″ from a straight line. This line passes to within 2″ the peak of the submm source FIR4 of OMC-1 (Mezger, Wink and Zylka 1990) and the mm continuum peak CS3 (Mundy et al. 1986); it also cuts across the red and blue SiO-outflow lobes recently discovered some 5-10″ to either side of FIR4 (Ziurys, Wilson and Mauersberger 1990). It thus seems that the “base” of our large-scale CO jet can be seen as well.

Transgressions and Regressions in the Barataria Bight Region of Coastal Louisiana

ABSTRACT There is a paucity of stratigraphic information in the Barataria, Louisiana, shoreline area between the Caminada/Moreau Headland and Point Chenier Ronquille. The geologic history of this coastal reach has been determined using a database that includes nearly one hundred vibracores, high resolution seismic data, carbon-14 dates, scrutiny of historical maps and a consolidation of regional investigations conducted by other researchers. The refinement of the Mississippi Delta lobe chronology is of primary interest to researchers of coastal Louisiana. At least three delta progradations have contributed to the Barataria geologic framework since 5000 yr B.P. The Bayou des Families lobe was first (4600 to 3600 yr B.P.) followed by Bayou Slue (2600 and 1900 yr B.P.) and then the Mississippi lobe (1000 yr B.P. to the present). The newer dataset suggests that the des Families lobe is older and the life span of the Bayou Blue lobe significantly longer than previously thought. The age of the Mississippi River lobe agrees with past researchers with the exception that the newer data allows recognition of an early and late phase of lobe construction.

High-resolution mapping of the bipolar outflow in NGC 2071 - Evidence for a wind-driven molecular outflow

The bipolar outflow in NGC 2071 has been mapped in the CS (J = 2-1), CS (J = 1-0), HCO(+) (J = 1-0), and HCN (J = 1-0) lines, using the 45-m telescope of Nobeyama Radio Observatory with the narrow beams of HPBW = 20 arcsec and 40 arcsec. It is found that the rest components of the CS (J = 2-1) and CS (J = 1-0) lines have cavities at the centers of the red and blue lobes of the CO high-velocity emission, and that a single peak of the CS spectra outside the CO red lobe splits into two peaks inside the lobe. These features of the CS emission strongly suggest that the bipolar outflow in NGC 2071 consists of two expanding dense bubbles which are driven by a stellar wind from the IR cluster. The high-resolution mapping also reveals the fact that the CS bubbles have a clumpy structure. Two of the clumps are located at the place where the shocked H2 emission was detected. This fact indicates that formation of the strong shock results from the collision between the high-velocity wind from the IR cluster and the clumps in the ambient cloud. In addition, around themore » IR cluster this observation shows a disklike condensation, whose size is smaller than the width of the CO high-velocity outflow. 35 refs.« less

A remarkable multilobe molecular outflow - Rho Ophiuchi East, associated with IRAS 16293-2422

view Abstract Citations (114) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Remarkable Multilobe Molecular Outflow: rho Ophiuchi East, Associated with IRAS 16293-2422 Mizuno, A. ; Fukui, Y. ; Iwata, T. ; Nozawa, S. ; Takano, T. Abstract Rho Ophiuchi East is one of the molecular outflows discovered in the Nagoya CO survey of star formation regions (Fukui et al., 1986) and was independently discovered by Wootten and Loren (1987). IRAS 16293-2422 is the driving source of the outflow. A detailed observational study of this outflow source in the J = 1-0 and J = 2-1 transitions of CO and in the (J, K) = (1, 1) and (2, 2) transitions of NH3 was made with angular resolutions of 17-80 arcsecs. The high-velocity CO emission has been resolved into four compact separate lobes, consisting of two pairs of bipolar lobes, in addition to an extended monopolar blueshifted lobe. The NH3 cloud has a size of 2.5 x 2.5 arcmin being peaked at 1.7 arcmin east of IRAS 16293-2422. This NH3 peak is located just toward the edge of one of the compact blue CO lobes, showing a blueshift of 0.5 km/s from the rest of the NH3 cloud. The momentum involved in the NH3 peak is nearly equal to that of the CO lobe. It is suggested that the CO lobe has dynamically interacted with the NH3 core, resulting in the acceleration of the NH3 core by 0.5 km/s. Publication: The Astrophysical Journal Pub Date: June 1990 DOI: 10.1086/168829 Bibcode: 1990ApJ...356..184M Keywords: Interstellar Matter; Molecular Clouds; Ophiuchi Clouds; Star Formation; Ammonia; Carbon Monoxide; Infrared Astronomy Satellite; Astrophysics; INTERSTELLAR: MOLECULES; NEBULAE: INDIVIDUAL NAME: RHO OPHIUCHI E full text sources ADS | data products SIMBAD (3)

High-resolution molecular observations of NGC 7538 IRS 1

This paper presents results of high-resolution (about 3 arcsec) observations of HCN and HCO(+) toward NGC 7538 IRS 1, carried out with the Berkeley-Illinois-Maryland Array and the NRAO 12-m telescope. The J = 1-0 transition of HCO(+) shows an elongated structure extending from the northeast to the southwest. The wings of the HCO(+) line show the blue lobe of an outflow which is in the same direction as the CO outflow in the source. A detailed comparison between individual HCN and HCO(+) emission peaks shows a definite anticorrelation, which is an indication of different mechanisms which excite the two molecules. 22 refs.

High-resolution observations of the B335 and L723 bipolar molecular outflows

view Abstract Citations (57) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Resolution Observations of the B335 and L723 Bipolar Molecular Outflows Moriarty-Schieven, G. H. ; Snell, Ronald L. Abstract Complete maps of the high-velocity (C-12)O emission of the B335 and L723 bipolar molecular outflows are presented, for which the angular resolution has been enhanced using maximum entropy. The B335 outflow appears to show a thin shell structure much like that of L1551 and lies nearly perpendicular to the line of sight, having an inclination out of the plane of the sky of only i = 9 + or - 1 deg. The outflow has a nearly constant opening angle from begining to end, where the outflow appears to have broken out of the cloud in both directions. Emission at the ends of the outflow shows signs of being reaccelerated. The mass of outflowing gas is about 1 percent of the molecular cloud and contains enough momentum and energy to disrupt the cloud core. The L723 outflow is very narrow and remains unresolved. Two nearly perpendicular axes of symmetry of the outflow suggest that the outflow axis has precessed. A curious sinuous ridge of redshifted emission traces the south edge of the blue lobe and may indicate a large velocity dispersion at the interface of the molecular outflow with the ambient cloud. Publication: The Astrophysical Journal Pub Date: March 1989 DOI: 10.1086/167247 Bibcode: 1989ApJ...338..952M Keywords: Carbon Monoxide; Maximum Entropy Method; Molecular Flow; Stellar Coronas; Stellar Winds; Angular Resolution; Morphology; Pre-Main Sequence Stars; Astrophysics; INTERSTELLAR: MOLECULES; NEBULAE: INDIVIDUAL ALPHANUMERIC: B335; NEBULAE: INDIVIDUAL ALPHANUMERIC: L723 (LYNDS 723); NEBULAE: INTERNAL MOTIONS full text sources ADS | data products SIMBAD (4)

Ammonia observations of regions with molecular outflows

view Abstract Citations (64) References (65) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ammonia Observations of Regions with Molecular Outflows Torrelles, J. M. ; Ho, P. T. P. ; Moran, J. M. ; Rodriguez, L. F. ; Canto, J. Abstract Using the 37-m antenna of Haystack Observatory nine regions of molecular outflow (S187, AFGL 490, L1455, R Mon, AFGL 961, GGD 27-28, L723, AFGL 2591, and PV Cep) are observed in the (1,1) inversion transition line of NH3. NH3 is detected in six of these regions. Most of the observed ammonia condensations are unresolved with 1.4-arcmin resolution, so that neither the morphology nor the orientation with respect to the outflows could be determined. The only exception is the NH3 condensation in L1455, which is resolved and appears to straddle one of the blue CO lobes and the red CO lobe. There also appears to be some extended weaker NH3 emission that may be related to the CO outflow. The NH3 condensation in L723 shows a velocity gradient, which would be consistent with a rotating structure with its major axis aligned perpendicular to the outflow axis. High-angular-resolution observations of ammonia are required to test this suggestion. An H2O maser is detected that may be associated with the outflow from PV Cep. A statistical study of the sources with known molecular outflows shows that about 90 percent of the bipolar outflows are associated with high-density gaseous condensations. However, the association with the nonbipolar outflows is only about 50 percent. This result suggests an important role for the surrounding high-density gas on the collimation of the bipolar outflows. Publication: The Astrophysical Journal Pub Date: August 1986 DOI: 10.1086/164464 Bibcode: 1986ApJ...307..787T Keywords: Ammonia; Interstellar Gas; Molecular Flow; Nebulae; Astronomical Maps; Carbon Monoxide; Emission Spectra; Interstellar Masers; Radio Sources (Astronomy); Water Masers; Astrophysics; INTERSTELLAR: MOLECULES; MASERS; NEBULAE: GENERAL; RADIO SOURCES: LINES full text sources ADS | data products SIMBAD (51) NED (1)

A Colorimeter for Pyrotechnic Smokes*

A tristimulus photoelectric colorimeter has been designed to measure the chromaticities of pyrotechnic smokes having highly saturated colors. To obtain a compact housing for three multiplier phototubes, “head-on” type (RCA 5819) phototubes are used. For high sensitivity and stability the photometric units are three Photovolt Multiplier Photometers, Model 520-M. To minimize edge effects and rear wall reflection, the smoke chamber was designed as a 36-inch cube. The chamber is illuminated by four 150-watt flood lamps placed to yield uniform illumination on the viewing window. Three filters were designed to approximate the daylight CIE standard observer functions for the source-filter-phototube combinations of the instrument. As the CIE y¯ and z¯ functions are unimodal, little difficulty was encountered in designing the filters to approximate these functions. The CIE x¯ function, which is bimodal, required a divided filter to approximate its two lobes. The filter constructed was composed of two sectors, one approximating the “blue lobe,” the other approximating the “red lobe,” of the x¯ function. Satisfactory results have been obtained with this colorimeter using Munsell papers as standards.

A colorimeter for pyrotechnic smokes

A tristimulus photoelectric colorimeter has been designed to measure the chromaticities of pyrotechnic smokes having highly saturated colors. To obtain a compact housing for three multiplier phototubes, “head-on” type (RCA 5819) phototubes are used. For high sensitivity and stability the photometric units are three Photovolt Multiplier Photometers, Model 520-M. To minimize edge effects and rear wall reflection, the smoke chamber was designed as a 36-inch cube. The chamber is illuminated by four 150-watt flood lamps placed to yield uniform illumination on the viewing window. Three filters were designed to approximate the daylight CIE standard observer functions for the source-filter-phototube combinations of the instrument. As the CIE y¯ and z¯ functions are unimodal, little difficulty was encountered in designing the filters to approximate these functions. The CIE x¯ function, which is bimodal, required a divided filter to approximate its two lobes. The filter constructed was composed of two sectors, one approximating the “blue lobe,” the other approximating the “red lobe,” of the x¯ function. Satisfactory results have been obtained with this colorimeter using Munsell papers as standards.