A5071035704- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Photocathodes and Microchannel Plates
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Calibration and Measurement Techniques
- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Gamma-ray bursts and supernovae
- Planetary Science and Exploration
- Space Exploration and Technology
- Relativity and Gravitational Theory
- Ionosphere and magnetosphere dynamics
- Space exploration and regulation
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Impact of Light on Environment and Health
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
Johns Hopkins University
2012-2025
Queen's University Belfast
2015-2016
University of Oklahoma
1999-2011
Maryland Space Grant Consortium
2002-2004
Maryland Sea Grant
2003-2004
Johns Hopkins University Applied Physics Laboratory
2002
Bloomberg (United States)
2001
University of Newcastle Australia
1996
John Hunter Hospital
1996
Los Alamos National Laboratory
1990
view Abstract Citations (124) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Possible Detection of a Dense Intergalactic Plasma Henry, R. C. ; Fritz, G. Meekins, J. F. Friedman, H. Byram, E. T. Observations in the 1.5-8 keV range indicate that isotropic X-ray background spectrum breaks at low energies, implying flux observed 0.27 keY has an independent origin. This soft is attributed to free-free emission from dense (105_106 particle cm-3),...
X-ray pulsations have been observed in the Crab Nebula at a frequency closely matching radio and optical pulsations. About 5 percent of total x-ray power nebula appears pulsed component. The form main pulse an interpulse separated by about 12 milliseconds.
I have derived the Kretschmann scalar for a general black hole of mass m, angular momentum per unit a, and electric charge Q. The gives amount curvature spacetime, as function position near (and within) hole. This allows one to display "appearance" itself, whether is merely stellar or supermassive at center an active galaxy. Schwarzschild holes, rotating electrically charged holes are all illustrated. Rotating discovered possess negative that not analogous saddle.
The results are reported of observations in narrow bands centered on 1115, 1425, and 1446 A the flux from an empty high-galactic-latitude region several stars. had been obtained with aid three ultraviolet-sensitive Geiger counters which were carried Aerobee-150 rocket launched White Sands missile range Mar. 13, 1969. provide a basis for setting upper limit to Coma cluster galaxies.
view Abstract Citations (98) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet observations of cool stars. VII. Local interstellar hydrogen and deuterium Lyman-alpha. McClintock, W. ; Henry, R. C. Linsky, J. L. Moos, H. High-resolution Copernicus spectra Epsilon Eri Ind containing L-alpha absorption lines are presented, reduced, analyzed. Parameters the toward these two stars derived independently, without any assumptions concerning...
An ultraviolet spectrometer aboard the Apollo 17 orbiting spacecraft attempted to measure emissions from lunar atmosphere. The only observed were a transient atmosphere introduced by landing engine. absence of atomic hydrogen implies that solar wind protons are converted molecules at surface.
Using the Goddard High Resolution Spectrograph onboard Hubble Space Telescope, we have observed Lyα absorption against stellar chromospheres along six lines of sight, with additional observations Mg II H and K five sight Fe four sight. We found near projected velocity local interstellar cloud (LIC) three The toward stars β Gem σ was only marginally consistent LIC. single component 31 Com had a that inconsistent LIC velocity. Three showed multicomponent structure. For star Eri required an...
We present a map of the diffuse ultraviolet cosmic background in two wavelength bands (FUV: 1530 Å and NUV: 2310 Å) over almost 75% sky using archival data from Galaxy Evolution Explorer (GALEX) mission. Most flux is due to dust-scattered starlight follows cosecant law with slopes 545 photons cm−2 s−1 sr−1 Å−1 433 FUV NUV bands, respectively. There strong correlation 100 μm Infrared Astronomy Satellite (IRAS) an average UV/IR ratio 300 (MJy sr−1)−1 band that 220 but significant variations...
We present new observations of the cosmic ultraviolet background (CUVB) at high Galactic latitudes ($|b| > 40^{\circ}$), made using Alice UV spectrograph on board New Horizons spacecraft. These were taken about 57 AU from Sun, outside much foreground emission affecting previous missions, and allowed a determination spectrum CUVB between 912 -- 1100~\AA\ 1400 1800~\AA. found linear correlation Planck E(B~-~V) with offsets zero-reddening $221 \pm 11$ photon units 1000~\AA\ $264 24$ \photu\...
Abstract We present new observations of the cosmic ultraviolet background (CUVB) at high Galactic latitudes (∣ b ∣ > 40 ∘ ), made using Alice UV spectrograph on board New Horizons spacecraft. These were taken about 57 au from Sun, outside much foreground emission affecting previous missions, and allowed a determination spectrum CUVB between 912–1100 Å 1400–1800 Å. found linear correlation Planck E ( B − V ) with offsets zero-reddening 221 ± 11 photon units 1000 264 24 1500 (4.4 0.2 nW m...
Abstract During 2023 September the Alice ultraviolet spectrograph on New Horizons (NH) spacecraft was used to map diffuse Lyα emission over most of sky, at a range ∼56.9 au from Sun. At that distance, models predict interplanetary medium Ly α emissions result comparable amounts resonant backscattering solar line by interstellar hydrogen atoms (H i ) passing through system, in addition an approximately isotropic background ∼50 ± 20 R local (LISM). The NH observations show no strong...
Murthy et al. (2025) (hereafter Paper I) have recently reported the discovery of unexpectedly bright diffuse extreme-ultraviolet radiation at high latitudes in both Northern and Southern Galactic Hemispheres. After correction for extinction by total interstellar dust direction each observation, spectra are nearly identical, suggesting that has a unique source likely originates halo our galaxy. The observed spectrum extends down to 912 Å, hydrogen absorption edge. Radiation even slightly...
view Abstract Citations (100) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Constraints on the Origin of Ultraviolet Upturn in Elliptical Galaxies from Hopkins Telescope Observations NGC 1399 Ferguson, Henry C. ; Davidsen, Arthur F. Kriss, Gerard A. Blair, William P. Bowers, Charles W. Dixon, Van Dyke Durrance, Samuel T. Feldman, Paul D. Henry, Richard Kruk, Jeffrey Moos, H. Warren Vancura, Olaf Long, Knox S. Kimble, Randy The giant...
view Abstract Citations (98) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hopkins Ultraviolet Telescope Observations of the Far-Ultraviolet Spectrum NGC 4151 Kriss, G. A. ; Davidsen, F. Blair, William P. Bowers, C. W. Dixon, V. Durrance, S. T. Feldman, D. Ferguson, H. Henry, R. Kimble, Kruk, J. Long, Knox Moos, Vancura, O. We observed far-ultraviolet spectrum Seyfert galaxy from 912 to 1860 A with during flight Astro-1 aboard space shuttle...
view Abstract Citations (62) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of the Soft X-Ray Background Davidsen, A. ; Shulman, S. Fritz, G. Meekins, J. F. Henry, R. C. Friedman, H. diffuse X-ray background over a hemisphere sky in galactic anticenter direction provide clear evidence for an excess intensity below 1 keV all directions. The correlation this low-energy flux with latitude and hydrogen column density implies that...
view Abstract Citations (65) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Free-Free Emission by Intergalactic Hydrogen. Field, George B. ; Henry, Richard C. The amount of free4ree emission intergalactic hydrogen is calculated and compared with observation. calculations are carried out for the steady-state model closed evolving models qo = 21 1. It shown that temperature medium must be less than 4 X 106 K (steady-state model) or 3 (qg 2' 1),...
view Abstract Citations (56) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Determination of Ionic Abundances in the Io Torus Using Hopkins Ultraviolet Telescope Moos, H. W. ; Feldman, P. D. Durrance, S. T. Blair, Bowers, C. Davidsen, A. F. Dixon, V. Ferguson, Henry, R. Kimble, Kriss, G. Kruk, J. Long, K. Vancura, O. Attention is given to a 415-1864-A spectrum emissions from torus with about 3-A resolution first order (830-1864 A) obtained...
view Abstract Citations (32) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Far-ultraviolet albedo of the moon. Lucke, R. L. ; Henry, C. Fastie, W. G. The and photometric function moon have been measured between 121.6 168.0 nm by comparing brightness moon, observed with an orbiting far-ultraviolet spectrometer during Apollo 17 mission, to solar simultaneously from a sounding rocket. instruments were carefully cross-calibrated. In contrast...
view Abstract Citations (61) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The X-Ray Spectra of the Crab Nebula and NP 0532 Fritz, Gilbert ; Meekins, John F. Chubb, Talbot A. Friedman, H. Henry, Richard C. X-ray pulsar in Nebula, integrated over energy range 0.5-9 keV, has a primarypulse profile slightly narrower than that its optical counterpart. pulsed fraction total emission varies smoothly from about 2 percent near 1 keV to 10 at 7...
view Abstract Citations (36) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-Ray Spectra of Several Discrete Cosmic Sources Meekins, J. F. ; Henry, R. C. Fritz, G. Friedman, H. Byram, E. T. Sco XR-1, Cyg and XR-2 are derived for the photon energy range 1.5-13 keV from proportional-counter measurements made on September 8, 1967. The spectrum XR-1 may be described by bremsstrahlung with a temperature (65 ± 5) X 1060 K. No simple power-law...
We have used GALEX observations of the North and South Galactic poles to study diffuse ultraviolet background at locations where light is expected be a minimum. find offsets 230 -- 290 photon units in FUV (1531 \AA) 480 580 NUV (2361 \AA). Of this, approximately 120 can ascribed dust scattered another 110 (190 NUV) extragalactic radiation. The remaining radiation is, as yet, unidentified amounts $120 180$ $300 400$ NUV. that molecular hydrogen fluorescence contributes when 100 $\mu$m surface...
Riemann curvature invariants are important in general relativity because they encode the geometrical properties of spacetime a manifestly coordinate-invariant way. Fourteen such required to characterize four-dimensional general, and Zakhary McIntosh showed that as many seventeen can be certain degenerate cases. We calculate explicit expressions for all these Zakhary–McIntosh Kerr–Newman metric describes around black holes most kind (those with mass, charge, spin), confirm related by eight...