Types O Research Articles

The unstable 06.5f?p star HD 148937 and its interstellar environment

The massive, early-type star HD 148937 (spectral type O6.5f?p) is surrounded by a unique set of nebulosities. A spherically symmetric Strömgren sphere (Radius ≃ 25 pc), an ellipsoidal filamentary nebulosity (semimajor axis ≃ 5 pc) interpreted as a stellar-wind-blown shell, and a bipolar nebular complex (semimajor axis ≃ 1 pc) with HD 148937 located in the apparent center of symmetry. Here we report on observations of these nebulosities (narrow-band CCD imaging, IDS spectrophotometry, high resolution (ΔV ≃ 7 km sec−1) spectroscopy) in an attempt to establish a consistent model of HD 148937 and its nebulosities.

An empirical H-gamma luminosity calibration for class V-III stars

view Abstract Citations (53) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An empirical H-gamma luminosity calibration for class V-III stars. Millward, C. G. ; Walker, G. A. H. Abstract The W(H-gamma)-M(v) relation for spectral types O to early A of the luminosity classes III-V is calibrated, on the basis of high signal/noise Reticon spectra for 87 members of eight open clusters and associations as well as 37 reliable parallax stars, to a mean probable dispersion of + or - 0.28 mag. Although no spectral type corrections are required, stellar evolution probably affects the construction of the new calibration, so care should be exercised in determinations of distance moduli from slightly evolved cluster sequences. Systematic departures from the calibration may be present for stars with V sin i not less than 220-250 km/sec. A comparison of the new calibration with other early-type ones shows that it is 1.2 mag brighter than Petrie's (1965) H-gamma calibration at spectral type O6, and 0.7 mag brighter at A3. Publication: The Astrophysical Journal Supplement Series Pub Date: January 1985 DOI: 10.1086/190995 Bibcode: 1985ApJS...57...63M Keywords: Early Stars; H Gamma Line; Star Clusters; Stellar Luminosity; Stellar Spectra; Calibrating; Spectral Line Width; Stellar Evolution; Stellar Rotation; Astrophysics full text sources ADS | data products SIMBAD (143)

Sulfur isotope fractionation during SO3(2-) reduction by different clostridial species.

Sulfur isotope composition patterns for sulfide evolved from cultures supplemented with 1 mM Na2SO3, suggested that an inducible dissimilatory type SO3(2-) reduction pathway, as previously found in C. pasteurianum, probably exists in many clostridial species. Data are presented for five additional species which include pathogens and nonpathogens.

IUE OBSERVATIONS OF THE LOW-EXCITATION PLANETARY NEBULA TC-1.

ABSTRACT Ultraviolet observations of Tc-1 confirm that the object is a low excitation planetary nebula with a central star of type O7. The nebular spectrum has few emission lines and the P Cygni character of the C IV line remains uncertain. A radial velocity of -95 km/s is found from the semiforbidden C III wavelength 1909 line, and an extinction of 0.22 m from the wavelength 2200 absorption feature.

An optical study of IC 1470

IC 1470 (S156) is a compact H II region associated with an extensive molecular cloud in the Perseus arm. The central star of IC 1470 was observed by Chopinet et al. (1973) who suggest that the exciting star is of spectral type O7. The present investigation is concerned with additional optical data with high spatial resolution and accurate emission line velocities across the nebula. A quantitative comparison is conducted of representative emission line strengths of IC 1470 and M8. It is concluded that IC 1470 has a nebular spectrum similar to M8 and appears to be an H II region excited by a single O7 star. It represents an object formed close to the edge of a molecular cloud, and its ionizing radiation is penetrating the intercloud gas, producing a 'blister' on its edge.

AISI TYPE O7

Abstract AISI Type O7 is a high-carbon, low-alloy tools designed for many types of cold-work cutting tools where the high-alloy, high-speed steels are not required. It has moderate hardenability, develops high hardness, holds a keen cutting edge and has excellent resistance to abrasion. Type O7 is used for a wide range of cold-working tools such as broaches, blanking dies, punches, thread-rolling dies, paper knives and wood-working tools. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, and machining. Filing Code: TS-404. Producer or source: Tool steel mills.

The bipolar nebula S106 - Photometric, polarimetric, and spectropolarimetric observations

view Abstract Citations (79) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The bipolar nebula S 106 : photometric polarimetric, and spectropolarimetric observations. Staude, H. J. ; Lenzen, R. ; Dyck, H. M. ; Schmidt, G. D. Abstract Multicolor photometry, photopolarimetry and spectropolarimetry is presented for the bipolar nebula S 106, a compact H II region associated with a massive molecular cloud, and for field stars projected on it. UVBRI photometry and broadband polarimetry of field stars is used to derive a foreground extinction and polarization which yields a distance to the molecular complex of 600 + or - 100 pc. Photopolarimetry of the nebular lobes in the optical and IR regions indicates the polarization vectors to be nearly perpendicular to the radius vector to the point source identified as the single stellar source, which is apparently due to grain alignment in the equatorial dust lane. Spectrophotometry of the brightest knot in the southern lobe of the nebula, reveals emission lines typical of a radiatively excited H II region, and indicates a portion of the line flux to be reflected radiation from the central star, identified as spectral type O9 V. Publication: The Astrophysical Journal Pub Date: April 1982 DOI: 10.1086/159807 Bibcode: 1982ApJ...255...95S Keywords: Astronomical Photometry; Nebulae; Polarimetry; Spectrophotometry; H Ii Regions; Hydrogen Ions; Interstellar Extinction; Water Masers; Astronomy full text sources ADS | data products SIMBAD (1)

Serum resistance among Escherichia coli strains causing urinary tract infection in relation to O type and the carriage of hemolysin, colicin, and antibiotic resistance determinants

The sensitivity to normal human serum of 91 smooth strains of Escherichia coli isolated from urinary tract infections was determined. Production of hemolysin, which was common and associated primarily with the types O4, O6, O18, and O75, was significantly correlated with high levels of serum resistance, both within the total population and within individual O types. In contrast, serum resistance was not significantly associated with antibiotic resistance (whether transmissible or not), with colicinogeny in general, or with colicin V production in particular. This indicates that the carriage of R and ColV plasmids, shown previously to be capable of conferring increased levels of serum resistance on individual strains of E. coli isolated from other sources, does not play an important part in determining the serum sensitivity of the E. coli population involved in urinary tract infection.

THE YOUNG OPEN CLUSTERS BERKELEY 62 AND BERKELEY 86.

ABSTRACT Berkeley 62 and Berkeley 86, two previously unstudied open clusters whose brightest probable members are OB stars are discussed. Photoelectric UBV observations show Be 62 lying at a distance of 2.05 + or - 0.24 kpc with a reddening of E(B-V) = 0.86 + or - 0.04 and earliest spectral type B1. It is found that Be 86 lies 1.72 + or - 0.20 kpc from the sun with a reddening of E(B-V) = 0.96 + or - 0.07 and earliest spectral type O9. Spectroscopic observations of six stars in Be 86 indicate a ratio E(U-B)/E(B-V) = 0.77 + or - 0.05, which is in agreement with other determinations made in the Cygnus region. It is noted that both clusters are young enough to be used as spiral arm tracers.

Stable isotope fractionation by Clostridium pasteurianum. 4. Sulfur isotope fractionation during enzymatic S3O6(2-), S2O3(2-), and SO3(2-) reductions.

Cell-free extracts from Clostridium pasteurianum grown on SO3(2-) utilize H2 to reduce S3O6(2-), S2O3(2-), SO3(2-) to H2S at a much faster rate than extracts from SO4(2-)-grown cells. This further supports the concept of an inducible dissimilatory type SO3(2-) reductive pathway in this organism. 35S dilution experiments further support the concept that S3O6(2-) and S2O3(2-) are pathway intermediates. The inducible SO3(2-) reductase is ferredoxin linked and the kinetics of the reduction and the sulfur isotope fractionation of the product can be altered by altering the growth conditions. The attending sulfur isotope fractionations are similar to those observed during the chemical decomposition of these compounds. In the case of S2O3(2-), 35S labelling experiments verified the conclusions derived from the stable isotope fractionation data concerning the relative reduction rates of the sulfane and sulfonate sulfurs. The reduction rates were also affected by enzyme concentration. The integrity of the whole cell is a necessary requirement for the large inverse isotope effects previously reported.

A Subsynchronous Oscillation Relay???Type SSO

A Subsynchronous Oscillation Relay???Type SSO

The ultraviolet spectrum of the O-type subdwarf HD 49798

The O-type subdwarf (O6p) single-lined spectroscopic binary HD 49798, with an orbital period of 1.5477 d, has been observed by the International Ultraviolet Explorer satellite, to aid in analyses of O type photospheres. Four high resolution (0.1A) spectra are found in the far-ultraviolet region, and two high resolution (0.2A) spectra are found in the mid-ultraviolet region. Numerous absorption lines are identified in the spectra of the star, most of which are attributable to Fe V lines at wavelengths of 1270 to 1500 A. Fe IV lines are also identified at wavelengths of 1500 to 1860 A. The strong Fe V features are found to have no corresponding analogs in the Kurucz and Peytremann (1975) list, and the total line blanketing for stars of spectral type O6 to B0 is discovered to be underestimated by at least a factor of four. In addition, mass loss from the subdwarf observed in the N V resonance doublet at wavelengths of 1238 A and 1242 A is discussed, indicating the existence of a hot stellar wind.

Application of Subsynchronous Oscillation Relay???Type SSO

Application of Subsynchronous Oscillation Relay???Type SSO

Systematic variations in the spectrum of Theta-1 Orionis C

view Abstract Citations (45) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Systematic variations in the spectrum of tet1 Orionis C. Walborn, N. R. Abstract The spectrum of Theta-1 Ori C (Orion Trapezium) has been observed to change progressively from type O6 to O4 during 7 consecutive nights. This observation supports the reality of an even greater range of variation shown by scattered spectrograms obtained over a longer time span. Concurrently, variations are seen in the profile of He II 4686 A, both similar and in addition to the kinds described by Conti. Some possible implications of these variations with regard to effects on the surrounding nebulosity, and to a connection with the Trapezium X-ray source, are briefly pointed out, and several further observations are suggested. Publication: The Astrophysical Journal Pub Date: January 1981 DOI: 10.1086/183438 Bibcode: 1981ApJ...243L..37W Keywords: Early Stars; O Stars; Orion Nebula; Stellar Spectra; Variable Stars; Periodic Variations; Stellar Luminosity; X Ray Sources; Astronomy full text sources ADS | data products SIMBAD (1)

Spectroscopic studies of O-type binaries. VI - The quadruple system QZ Carinae /HD 93206/

view Abstract Citations (26) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectroscopic studies of O-type binaries. VI. The quadruple system QZCar (HD 93206). Morrison, N. D. ; Conti, P. S. Abstract QZ Carinae is an O-type, double-lined, eclipsing binary in the Carina Nebula. A radial-velocity study shows that this system actually consists of two single-lined spectroscopic binaries in the same line of sight, probably in wide orbit about each other. In one of these binaries, which undergoes eclipses with period 5.9980 days, the primary has spectral type roughly O9 III and produces the weaker of the two observed sets of spectral lines. The star responsible for the stronger set is 0.6 mag brighter, has spectral type O9.5 I, and moves in an eccentric orbit about an unseen companion with period 20.73 days. Radial velocities are presented and orbits are determined for both systems. A systematic difference in velocity between He I and Si IV in the supergiant suggests appreciable mass loss. Spectrograms show broad H-alpha emission, which appears to vary in phase with the eclipsing binary. Publication: The Astrophysical Journal Pub Date: July 1980 DOI: 10.1086/158101 Bibcode: 1980ApJ...239..212M Keywords: Early Stars; Eclipsing Binary Stars; O Stars; Quadrupoles; Stellar Spectra; Emission Spectra; H Alpha Line; Radial Velocity; Stellar Rotation; Astrophysics full text sources ADS | data products SIMBAD (1) Related Materials (5) Part 1: 1976ApJ...204..797B Part 2: 1976ApJ...207..502C Part 3: 1977ApJ...218..431M Part 4: 1978ApJ...224..558M Part 5: 1980ApJ...238..184C

THE OPEN CLUSTER NGC 3293 AND THE OB COMPLEX IN CARINA.

ABSTRACT Photoelectric measures in UBVRI of 46 stars in and around the open cluster NGC 3293 are presented. A distance modulus of V0 - Mv equals 12.1 plus or minus 0.15 (s.d.), corresponding to 2.6 kpc, was derived from the photometric data for 34 member stars. This is similar to distances found for other young groups in the Carina region. One M supergiant and one Be star are members of the cluster. The brightest stars on the main sequence are of type B1. Several stars that have evolved away from the upper main sequence have been classified as giants and supergiants. The age of the cluster is about 7-million years. The star HD 91824 (no. 1), spectral type O7 V((f)), is not a member of the group. The insterstellar reddening is normal in front of this cluster.

EQUIVALENT WIDTHS AND NARROW-BAND PHOTOMETRY OF THREE STELLAR LINES.

ABSTRACT Equivalent widths of the H-alpha, H-beta and 7774-A O I lines obtained from Michelson-Fourier spectra for 43 stars of types O6 to G2 are compared with narrow-band photometry corresponding to those spectral features. The results indicate that narrow-band photometry of stellar lines can be applied to fainter stars than can Michelson-Fourier spectroscopy, but at the expense of losing some astrophysical information, and that the internal photometric errors are low. It is concluded that narrow-band photometry is a natural choice for deriving physical parameters.

Escherichia coli in Bacteremia: K and O Antigens and Serum Sensitivity of Strains from Adults and Neonates

Comparisons of O- and K-antigenic types and serum sensitivity were carried out with 149 strains of Escherichia coli isolated from adults with bacteremia and 46 strains from neonates with bacteremia. O-antigenic types O6, O4, O2, O16, O18, and O7 were observed most frequently, but their relative prevalence did not differ materially between adult and neonatal bacteremias. A greater proportion of strains from neonatal bacteremia contained K1 antigen and were autoagglutinable compared with strains from adult bacteremia, although K1 was the most frequent K antigen found in strains from adults. K-antigen-containing strains did not appear to be associated with enhanced severity of bacteremia, but nontypable strains, auto-agglutinable strains, and strains of O-antigenic types O4, O6, and O8 were associated with a greater frequency of shock and fatal outcome in adults. No differences could be detected between the serum sensitivities of E. coli isolated from adult bacteremia and those from neonatal bacteremia. K antigen did not affect serum sensitivity, but E. coli strains of O types O18, O2, O4, and O7 were more serum-resistant than other E. coli. Bacteremia caused by serum-sensitive E. coli was less often associated with shock and death than bacteremia caused by serum-resistant E. coli.

Means of increasing the effectiveness and quality of foundations constructed of cast-in-place piles

1. The type SO-2, SO-1200, and MBS-1.7 apparatus currently used to drill holes for cast-in-place piles provide for high drilling productivity, but do not permit complete cleaning of the base of the hole. It is necessary to fit their working devices with attachments to clean the hole bottoms and taper sections.

Distribution of R plasmids among the Q-antigen types of Escherichia coli isolated from various clinical sources.

A total of 655 Escherichia coli strains from various clinical sources were O-antigen typed, and the serological properties were correlated with R-plasmid carriage. Of the 655 strains, 224 were resistant to one or more antibiotics and 148 of these carried R plasmids. The distribution of O-antigen types among the susceptible strains was similar to that reported previously by others in England. The O-antigen types among the R(+) strains showed some similarities to those found in susceptible strains, but O-antigen types O8, O9, O17, O18 and, perhaps, O101 and O107 were more common in the R(+) than in the susceptible series. There is therefore some overlap between the O-antigen types of E. coli prevalent in R(+) strains from clinical cases and from human and animal fecal sources.