Far-ultraviolet background observations at high galactic latitude. II - Diffuse emission

1986 ◽  
Vol 311 ◽  
pp. 969 ◽  
Author(s):  
J. B. Holberg
Keyword(s):  
Galactic Latitude ◽  
Diffuse Emission ◽  
High Galactic Latitude ◽  
Far Ultraviolet

scholarly journals Imaging Large– and Small–Scale Structures of the Far Ultraviolet Background with the Faust Instrument

1990 ◽  
Vol 139 ◽  
pp. 449-452 ◽  
Author(s):  
M. Lampton ◽  
S. Bowyer ◽  
J. M. Deharveng
Keyword(s):  
Angular Resolution ◽  
Photon Counting ◽  
Field Of View ◽  
Small Scale ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Photon Counting Detector ◽  
Scale Structures ◽  
Far Ultraviolet ◽  
Small Scale Structures

The FAUST telescope is an ultraviolet survey instrument that features a wide 8° field of view, ~1′ angular resolution, and a photon counting detector. Operating in the 1400–1800 Å band, it will be sufficiently sensitive to detect blue mv =17 objects in a single 20 minute night. The instrument is part of the ATLAS-1 shuttle mission, presently scheduled for flight in May 1991. A substantial number of high galactic latitude fields will be investigated, with particular emphasis on studies of the origin of the diffuse far UV background.

scholarly journals Polarized diffuse emission at 2.3 GHz in a high Galactic latitude area

2005 ◽  
Vol 360 (1) ◽  
pp. L10-L14 ◽  
Author(s):  
E. Carretti ◽  
D. McConnell ◽  
N. M. McClure-Griffiths ◽  
G. Bernardi ◽  
S. Cortiglioni ◽  
...  
Keyword(s):  
Galactic Latitude ◽  
Diffuse Emission ◽  
High Galactic Latitude

scholarly journals Galactic diffuse gamma-ray emission at TeV energy

2020 ◽  
Vol 633 ◽  
pp. A94 ◽  
Author(s):  
A. Neronov ◽  
D. Semikoz
Keyword(s):  
Emission Spectrum ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Galactic Latitude ◽  
Diffuse Emission ◽  
Large Area ◽  
High Galactic Latitude ◽  
Galactic Emission ◽  
Significant Difference

Context. Measuring the diffuse Galactic γ-ray flux in the TeV range is difficult for ground-based γ-ray telescopes because of the residual cosmic-ray background, which is higher than the γ-ray flux by several orders of magnitude. Its detection is also challenging for space-based telescopes because of low signal statistics. Aims. We characterise the diffuse TeV flux from the Galaxy using decade-long exposures of the Fermi Large Area Telescope. Methods. Considering that the level of diffuse Galactic emission in the TeV band approaches the level of residual cosmic-ray background, we estimated the level of residual cosmic-ray background in the SOURCEVETO event selection and verified that the TeV diffuse Galactic emission flux is well above the residual cosmic-ray background up to high Galactic latitude regions. Results. We study spectral and imaging properties of the diffuse TeV signal from the Galactic plane. We find much stronger emission from the inner Galactic plane than in previous HESS telescope estimates (lower bound). We also find a significant difference in the measurement of the Galactic longitude and latitude profiles of the signal measured by Fermi and HESS. These discrepancies are presumably explained by the fact that regions of background estimate in HESS have non-negligible γ-ray flux. Comparing Fermi measurements with those of ARGO-YBJ, we find better agreement, with the notable exception of the Cygnus region, where we find much higher flux (by a factor 1.5). We also measure the TeV diffuse emission spectrum up to high Galactic latitude and show that the spectra of different regions of the sky have spectral slopes consistent with Γ = 2.34 ± 0.04, which is harder than the slope of the locally observed spectrum of cosmic rays with energies 10–100 TeV, which produce TeV diffuse emission on their way through the interstellar medium. We discuss the possible origin of the hard slope of the TeV diffuse emission. Conclusions. Fermi/LAT provides reliable measurements of the diffuse Galactic emission spectrum in the TeV range, which are almost background free at low Galactic latitudes. The diffuse flux becomes comparable to the residual cosmic-ray background at Galactic latitudes |b| > 50°. Its measurement in these regions might suffer from systematic uncertainty stemming from the uncertainty of our phenomenological model of the residual cosmic-ray background in the Pass 8 Fermi/LAT data.

scholarly journals SAO 244567 (HEN1357): A Post-Agb Star which has turned into a Planetary Nebula within the last 20 years

1998 ◽  
Vol 11 (1) ◽  
pp. 358-358
Author(s):  
M. Parthasarathy
Keyword(s):  
Planetary Nebula ◽  
Far Infrared ◽  
Central Star ◽  
Terminal Velocity ◽  
Galactic Latitude ◽  
Iras Source ◽  
High Galactic Latitude ◽  
Alpha Emission ◽  
Early Type Star ◽  
Emission Strength

SAO 244567 (Henl357) (IRAS 17119-5926) is a high galactic latitude (1 = 331°, b = −12°) early type star, originally classified as a B or A type H-alpha emission line star by Henize (1976). It is an IRAS source with far infrared colours similar to planetary nebulae. The IUE ultraviolet spectra obtained during the last eight years show that the central star is rapidly evolving. It is found that the central star of this young PN has faded by a factor of 3 within the last seven eight years. The terminal velocity of the stellar wind has decreased from −3500 km/sec in 1988 to almost zero in 1994. In 1988 the C IV (1550A) line which was a P-Cygni profile with strong absorption component had almost vanished by 1994. The CIII] 1909A emission strength increased markedly within 4 years from 1988 to 1992. The optical spectra obtained since 1990 shows very clearly only the nebular spectrum which is very similar to that of low excitation planetary nebula. The optical spectrum of SAO 244567 obtained in 1971 shows that it was a post-AGB B 1 or B2 supergiant at that time. This result shows that SAO 244567 has turned into a planetary nebula within the last 20 years. Recently Bobrowsky (1994) obtained narrowband optically resolved images in both H-beta and [OIII] 5007A with the HST planetary camera which revealed a well resolved nebula of size 2 seconds of arc. In this paper we discuss the recent new results.

scholarly journals Unexpected circular radio objects at high Galactic latitude

2021 ◽  
Vol 38 ◽  
Author(s):  
Ray P. Norris ◽  
Huib T. Intema ◽  
Anna D. Kapińska ◽  
Bärbel S. Koribalski ◽  
Emil Lenc ◽  
...  
Keyword(s):  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Square Kilometre Array ◽  
Pilot Survey ◽  
The Universe

Abstract We have found a class of circular radio objects in the Evolutionary Map of the Universe Pilot Survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs, about one arcmin diameter, that are unlike other objects previously reported in the literature. We explore several possible mechanisms that might cause these objects, but none seems to be a compelling explanation.

scholarly journals Detection of Hα Emission on High Velocity 21 cm Clouds

1990 ◽  
Vol 139 ◽  
pp. 193-198
Author(s):  
Guido Münch ◽  
Eckhart Pitz
Keyword(s):  
High Velocity ◽  
Galactic Latitude ◽  
Emission Rates ◽  
High Galactic Latitude ◽  
Continuum Intensity ◽  
Lyman Continuum ◽  
Local Standard ◽  
Direct Measurements ◽  
Hα Emission ◽  
Local Standard Of Rest

The measurement of Hα emission on two high galactic latitude clouds known to emit 21 cm lines with local standard of rest (LSR) velocities of −50 and −85 km s−1 is reported. The Hα lines have been found nearly at the velocities of the 21 CM features and have emission rates of 0.2 Rayleigh. The diffuse Lyman continuum intensity required to produce HI ionization at the measured rate is in agreement with the direct measurements made with the ultraviolet (UV) spectrometer of the Voyager 2 spacecraft.

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