Galactic neutral hydrogen emission-absorption observations from Arecibo

1978 ◽  
Vol 36 ◽  
pp. 77 ◽  
Author(s):  
J. M. Dickey ◽  
Y. Terzian ◽  
E. E. Salpeter
Keyword(s):  
Neutral Hydrogen ◽  
Hydrogen Emission

Interstellar Neutral Hydrogen Emission Profile Structure

2004 ◽  
Vol 127 (1) ◽  
pp. 394-407 ◽  
Author(s):  
Gerrit L. Verschuur
Keyword(s):  
Neutral Hydrogen ◽  
Emission Profile ◽  
Hydrogen Emission

A deep search for 21 CM neutral hydrogen emission in the tightly bound globular cluster NGC 6388

1989 ◽  
Vol 97 ◽  
pp. 1708 ◽  
Author(s):  
David K. Lynch ◽  
Phillip F. Bowers ◽  
John B. Whiteoak
Keyword(s):  
Globular Cluster ◽  
Neutral Hydrogen ◽  
Hydrogen Emission

Galactic Neutral Hydrogen Emission Profile Structure

1999 ◽  
Vol 118 (3) ◽  
pp. 1252-1267 ◽  
Author(s):  
Gerrit L. Verschuur ◽  
Anthony L. Peratt
Keyword(s):  
Neutral Hydrogen ◽  
Emission Profile ◽  
Hydrogen Emission

scholarly journals Neutral Hydrogen in the Bar of NGC 4151

1996 ◽  
Vol 157 ◽  
pp. 242-243
Author(s):  
C. G. Mundell ◽  
A. Pedlar ◽  
D. L. Shone ◽  
M. W. Asif ◽  
A. Robinson ◽  
...  
Keyword(s):  
Crucial Role ◽  
Large Scale ◽  
Complex Structure ◽  
Outer Part ◽  
Neutral Hydrogen ◽  
High Sensitivity ◽  
Hydrogen Emission ◽  
Ngc 4151 ◽  
Armed Spiral

Bars are thought to play a crucial role in the fueling of AGN (see e.g., Mundell et al., in these proceedings and references therein), and as part of a project to investigate this, we have studied the neutral hydrogen structure in the bar of the Seyfert 1.5 galaxy NGC 4151.High-sensitivity VLA observations have enabled us to image the neutral hydrogen emission from the bar of NGC 4151 in unprecedented detail, and is a continuation of the work by Pedlar et al. (1992).Figure 1 shows images of integrated neutral hydrogen emission. The large scale emission extends over approximately 20 kpc and the outer part consists of a well-defined two-armed spiral which originates from a fat bar at a radius of about 5 kpc. The bar shows complex structure, including two sharp features which are reminiscent of the shocks seen in many simulations, e.g., Athanassoula (1992). These features appear to join the central 1-kpc ring discovered by Vila-Vilaró et al. (1994), and for which there appears a partial counterpart in neutral hydrogen emission.

TheSpitzer Space TelescopeFirst Look Survey: Neutral Hydrogen Emission

2005 ◽  
Vol 129 (4) ◽  
pp. 1968-1977 ◽  
Author(s):  
Felix J. Lockman ◽  
J. J. Condon
Keyword(s):  
Neutral Hydrogen ◽  
Hydrogen Emission

scholarly journals Evidence for Energetic Neutral Hydrogen Emission from Solar Particle Events

2021 ◽  
Vol 923 (2) ◽  
pp. 195
Author(s):  
G. M. Mason ◽  
M. E. Greenspan ◽  
S. G. Kanekal ◽  
R. A. Leske ◽  
M. D. Looper ◽  
...  
Keyword(s):  
Solar Flares ◽  
Neutral Hydrogen ◽  
Solar Energetic Particle ◽  
Cutoff Rigidity ◽  
Hydrogen Atoms ◽  
Survey Period ◽  
Solar Particle Events ◽  
X Ray ◽  
Hydrogen Emission ◽  
Solar Energetic Particle Events

Abstract We report the probable detection of energetic neutral hydrogen atoms (ENAs) at >0.8 MeV in several large solar energetic particle events observed between 1997 and 2004. The low Earth orbiting SAMPEX satellite detected transient increases of quasi-trapped equatorial protons beginning typically ∼3 hr after the X-ray flare and lasting for up to several hours. Since the magnetic cutoff rigidity is >10 GV at the magnetic latitude where the particles were observed, we interpret the signal as due to ENAs that penetrate Earth’s magnetic field and charge exchange in the upper atmosphere, whereupon the charged particles may become trapped. One event outside our survey period (2006 December 5) had previously reported solar flare ENAs, the only example of this phenomenon of which we are aware. Although the statistics are limited, the events we report suggest that the ENAs are produced as the flare-associated coronal mass wjection moves through the corona, as concluded previously for the 2006 December 5 event. The finding of ENAs emitted in conjunction with large solar flares opens a new avenue to understanding these events.

scholarly journals Optimal Multiwavelength Source Detection: Experience Gained from the WISE Mission

2012 ◽  
Vol 29 (3) ◽  
pp. 269-275 ◽  
Author(s):  
K. A. Marsh ◽  
T. H. Jarrett
Keyword(s):  
Neutral Hydrogen ◽  
Point Sources ◽  
Detection Sensitivity ◽  
Source Spectrum ◽  
Source Detection ◽  
Imaging Data ◽  
Data Cubes ◽  
Hydrogen Emission ◽  
Chi Squared ◽  
Potential Benefits

AbstractWe discuss the optimal detection of point sources from multiwavelength imaging data using an approach, referred to as MDET, which requires no prior knowledge of the source spectrum. MDET may be regarded as a somewhat more general version of the so-called ‘chi-squared’ technique. We describe the theoretical basis of the technique, and show examples of its performance with four-channel infrared broadband imaging data from the WISE mission. We also discuss the potential benefits of applying it to the multifrequency data cubes of the ASKAP surveys, and suggest that it could increase the detection sensitivity of searches for neutral hydrogen emission at moderately high redshifts.

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