Search NASA⌕ Search

SEARCH · Search NASA

Results for “Hg-Mn”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Chemical abundances in Hg-Mn stars

An abundance analysis has been conducted of 21 elements in 21 Hg-Mn, two Si-Cr, and six normal stars using model atmospheres and high-dispersion spectroscopy in the visible and UV. Manganese line strengths imply abundances that correlate well with stellar effective temperature. Within the studied sample of Hg-Mn stars there appears to be no correlation of abundances of any element with projected rotational velocity. Abundances in several Hg-Mn stars show patterns that are probably consistent with diffusion but difficult to reconcile with equilibrium nucleosynthesis. In general, no combination of gross stellar physical parameters is sufficient to characterize the patterns of line strengths observed in Hg-Mb Hg-Mn stars.

Heacox, W. D.↗
NASA NTRS1973

Ultraviolet photometry from the orbiting astronomical observatory. 8: The blue Ap stars

The filter photometers in the Wisconsin Experiment Package on OAO-2 were used to obtain data for a carefully selected set of 24 blue Ap stars and 31 comparison standard B and A dwarfs and giants for a program of relative photometry. Observations were made in seven bandpasses over the effective wavelength range 1430A-4250A. The Ap stars observed include members of the Si, Hg-Mn and Sr-Cr-Eu peculiarity classes. Most of them are too blue in B-V for their published MK spectral classes. The blue Ap stars are markedly deficient in emitted ultraviolet flux and are underluminous as compared to normal stars with the same UBV colors. The Hg-Mn stars appear less flux deficient in the ultraviolet for their UBV colors than do Si or Sr-cr-Eu stars. Most of the Ap stars observed possess ultraviolet flux distributions, or ultraviolet color temperatures, consistent with their published MK spectral classes to well within the classification uncertainties.

Leckrone, D. S.↗
NASA NTRS1977

Line blocking factors in the ultraviolet spectra of 35 B6 to A0 stars

Observed line-blocking factors for stars of spectral types B6 to A0 are presented which were measured on spectral tracings observed over the wavelength ranges from 2064 to 2158 A, 2496 to 2590 A, and 2775 to 2867 A with the S 59 spectrometer on the ESRO TD 1A satellite. Twenty-six stars having normal spectra were observed along with 12 stars having abnormal spectra. The results for normal and abnormal stars are compared to determine the changes in line blocking related to each type of spectral peculiarity. Detailed descriptions are given of the line-blocking factors in different spectral channels for a B8 supergiant, three Be stars, a shell star, two eclipsing binaries, an Hg-Mn star, and several peculiar B and A stars.

Underhill, A. B.↗
NASA NTRS1983

Interstellar C2 molecules in a Taurus dark cloud

Five relatively strong interstellar absorption lines of C2 in the (2-0) Phillips band near 8670 A have been detected toward the heavily reddened, late B star HD 29647, which lies behind a substantial part of one of the darkest regions of the nearest molecular cloud complex, the dark clouds of Taurus. Stringent upper limits on the C2 absorption toward two lightly reddened stars, Nu Cyg and Omicron And, are also reported. The observations yield a column density of about 9 x 10 to the 13th/sq cm, comparable to those of widely distributed molecules like CH and H2CO. Theoretical treatment of the data yields a kinetic temperature of 14 K and a mean density of less than about 1000/cu cm. A narrow, anomalously strong, stellar Mn II line yields a projected rotational velocity of less than about 7 km/s and is explained by previous identifications of the star as Hg-Mn peculiar.

Hobbs, L. M.↗
NASA NTRS1992

The abundances of the elements in sharp-lined early type stars

An International Ultraviolet Explorer (IUE) observing strategy that has yielded co-added spectra with enhanced S/N ratios for several A and B stars was established. New observations by Roby and Adelman using the same technique were added two new Hg-Mn stars into this sample. A long-term study of elemental abundances in this uniform, high-quality set of IUE spectra for 13 stars was begun. The first stages of this project are reported: abundances for N, Cr, Mn, Fe, Co, and Ni. The study of the Fe-peak elements show that our data set can provide accurate abundances and that abundances obtained from UV and optical spectra often are in good agreement. The groundwork for selfconsistent abundance analyses of more exotic elements in our long term project was provided.

Adelman, Saul J.↗
DOE OSTI2020

Materials Data on MnHg by Materials Project

MnHg is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mn is bonded in a body-centered cubic geometry to eight equivalent Hg atoms. All Mn–Hg bond lengths are 2.88 Å. Hg is bonded in a body-centered cubic geometry to eight equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn2Hg5 by Materials Project

Mn2Hg5 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Mn is bonded to two equivalent Mn and ten Hg atoms to form a mixture of distorted corner, edge, and face-sharing MnMn2Hg10 cuboctahedra. Both Mn–Mn bond lengths are 3.02 Å. There are six shorter (2.97 Å) and four longer (3.10 Å) Mn–Hg bond lengths. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 10-coordinate geometry to four equivalent Mn and six Hg atoms. There are a spread of Hg–Hg bond distances ranging from 3.02–3.29 Å. In the second Hg site, Hg is bonded in a 10-coordinate geometry to four equivalent Mn and six Hg atoms. Both Hg–Hg bond lengths are 3.02 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn3Hg by Materials Project

Mn3Hg is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mn is bonded to eight equivalent Mn and four equivalent Hg atoms to form distorted MnMn8Hg4 cuboctahedra that share corners with twelve equivalent MnMn8Hg4 cuboctahedra, edges with eight equivalent HgMn12 cuboctahedra, edges with sixteen equivalent MnMn8Hg4 cuboctahedra, faces with four equivalent HgMn12 cuboctahedra, and faces with fourteen equivalent MnMn8Hg4 cuboctahedra. All Mn–Mn bond lengths are 2.84 Å. All Mn–Hg bond lengths are 2.84 Å. Hg is bonded to twelve equivalent Mn atoms to form HgMn12 cuboctahedra that share corners with twelve equivalent HgMn12 cuboctahedra, edges with twenty-four equivalent MnMn8Hg4 cuboctahedra, faces with six equivalent HgMn12 cuboctahedra, and faces with twelve equivalent MnMn8Hg4 cuboctahedra.

36 MATERIALS SCIENCE↗