Astronomy and Astrophysics – Astrophysics
Scientific paper
Jul 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995a%26a...299..249q&link_type=abstract
Astronomy and Astrophysics, v.299, p.249
Astronomy and Astrophysics
Astrophysics
32
Interplanetary Medium, Ism: General, Solar Neighbourhood
Scientific paper
In 1993 and 1994, the Ultraviolet Spectrometers, aboard both Voyager 1 and 2, were used to study the Lyα glow pattern scattered by neutral hydrogen atoms at great distance from the sun, =~54 AU for Voyager 1 and 40 AU for Voyager 2. These data are characterized by a long integration time (=~10^4^s) and were obtained over a rather short period of time (10 days) to minimize effects of solar flux variations. When compared to a radiative transfer calculation of the Lyα glow pattern assuming a homogeneous distribution of hydrogen at large distance from the Sun, these maps present an excess of intensity seen in the direction of the incoming interstellar wind. This corresponds to a relative increase of =~17% over the expected value for Voyager 1 and =~10% for Voyager 2. An absolute estimate of this Lyman α intensity yields 10 to 15 Rayleigh for each spacecraft. The possible effects of longitudinal or latitudinal solar flux variations on these data, as well as the importance of the phase function when optical thickness at line center between the spacecraft and the Sun is more than 3, have been ruled out as a cause. We discuss here the possibility that this excess could be the result of a filtration of the neutral hydrogen at heliopause crossing caused by charge exchange between neutral hydrogen of interstellar origin and protons from the solar wind and the interstellar medium. Yet, this Lyman α intensity excess may also correspond to the first detection of the galactic Lyman α emission as hinted from the similarity of the observations for both spacecraft.
Bertaux Jean Loup
Lallement Rosine
Quémerais Eric
Sandel Bill R.
No associations
LandOfFree
A new source of Lyα emission detected by Voyager UVS: heliospheric or galactic origin? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A new source of Lyα emission detected by Voyager UVS: heliospheric or galactic origin?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A new source of Lyα emission detected by Voyager UVS: heliospheric or galactic origin? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1168415