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All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Spectral line profiles and luminosities of astrophysical water masers

The spectral line narrowing and rebroadening that occurs for astrophysical masers as a function of the emergent radiative flux is calculated for the prominent, 22 GHz masing transition of water. The increased line breadths due to hyperfine structure lead to reliable, essentially model-independent upper limits to the emergent flux that tend to be lower than other estimates for these masers. For many 22 GHz masers, including the outbursts in W49 and Orion, the observed line breadths are less than 0.9 km/s. For these, the upper limit to the emergent maser flux is 10 to the 10th K-sr when expressed in terms of the brightness temperature and the solid angle for beaming. It is concluded that the extreme brightness of the interstellar water masers is due to a high degree of beaming and not to more effective pumping.

Nedoluha, Gerald E.↗
DOE OSTI2020

Materials Data on KSr3 by Materials Project

KSr3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent Sr atoms. All K–Sr bond lengths are 4.24 Å. There are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a body-centered cubic geometry to four equivalent K and four equivalent Sr atoms. All Sr–Sr bond lengths are 4.24 Å. In the second Sr site, Sr is bonded in a body-centered cubic geometry to eight equivalent Sr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Sr by Materials Project

K3Sr is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a body-centered cubic geometry to four equivalent K and four equivalent Sr atoms. All K–K bond lengths are 4.47 Å. All K–Sr bond lengths are 4.47 Å. In the second K site, K is bonded in a body-centered cubic geometry to eight equivalent K atoms. Sr is bonded in a body-centered cubic geometry to eight equivalent K atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3Sr by Materials Project

K3Sr is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded to eight K and four equivalent Sr atoms to form KK8Sr4 cuboctahedra that share corners with twelve equivalent KK8Sr4 cuboctahedra, edges with eight equivalent SrK12 cuboctahedra, edges with sixteen KK8Sr4 cuboctahedra, faces with four equivalent SrK12 cuboctahedra, and faces with fourteen KK8Sr4 cuboctahedra. There are four shorter (4.49 Å) and four longer (4.67 Å) K–K bond lengths. All K–Sr bond lengths are 4.67 Å. In the second K site, K is bonded to eight equivalent K and four equivalent Sr atoms to form distorted KK8Sr4 cuboctahedra that share corners with four equivalent KK8Sr4 cuboctahedra, corners with eight equivalent SrK12 cuboctahedra, edges with twenty-four KK8Sr4 cuboctahedra, faces with six equivalent SrK12 cuboctahedra, and faces with twelve KK8Sr4 cuboctahedra. All K–Sr bond lengths are 4.49 Å. Sr is bonded to twelve K atoms to form SrK12 cuboctahedra that share corners with four equivalent SrK12 cuboctahedra, corners with eight equivalent KK8Sr4 cuboctahedra, edges with eight equivalent SrK12 cuboctahedra, edges with sixteen equivalent KK8Sr4 cuboctahedra, faces with four equivalent SrK12 cuboctahedra, and faces with fourteen KK8Sr4 cuboctahedra.

36 MATERIALS SCIENCE↗