Post by Andrei Tchentchik on Jun 22, 2019 14:28:36 GMT 2
(.#205).- A glittering hydrogen wall would encompass the Solar System.
A glittering hydrogen wall would encompass the Solar System.
By Tristan Vey – Updated on 31/08/2018 at 17:09
Artist's view of the gas bubble enveloping our Solar System and its interactions with the surrounding interstellar gas. NASA / Goddard Space Flight Center, Conceptual Image Lab.
An excess of UV radiation observed by the New Horizons probe, located on the edge of the Solar System, confirms the measurements of the Voyager probes and points to the possible existence of a "hydrogen wall".
What if a "hydrogen wall" emitting a weak ultraviolet radiation enveloped our solar system? This is one of the assumptions made by scientists from the New Horizons mission, whose probe is currently beyond Pluto, who detected a significant excess of photons in this wavelength range. Their results were presented earlier this month in the journal Geophysical Research Letters.
This is not the first time scientists have recorded this strange signal. The two Voyager probes, the first of which officially left the Solar System in 2012, both recorded this surprising excess of ultraviolet radiation more than 30 years ago.
"We are bathing in a very thin cloud of hydrogen lit by the Sun", decrypts Rosine Lallement, a specialist in the interactions between our Sun and the galactic cloud in which we are currently moving. "The Sun excites this hydrogen which starts to" shine "in the UV field. In principle, the further away from the sun, the lower the radiation. Exactly as the halo of light around a street lamp plunged into fog fades with distance. But we had already observed an excess of radiation at the time. And the further we get from the Sun, the better this excess comes out. "
An extragalactic source?
The presence of a hydrogen wall at the edge of our solar system could explain it in part. It is in fact a kind of "bead" formed by the interaction of the gases emitted by the Sun enveloping us (the solar wind) and the interstellar cloud in which we move. A bit like the wave that forms at the front of a boat. The interstellar hydrogen would be in some sort compressed by the "bubble" that surrounds us and accompanies us in our race to 90,000 km / h in the galaxy.
"But the models do not stick well to the observations," warns Rosine Lallement. "There may be an interaction between the ionized gas (electrically charged, that emitted by our star, Editor's note) and the neutral gas (of our galaxy, Ed) that we do not understand well. It's a very interesting problem. "
But there is another hypothesis: that this extra UV radiation comes from even further. "It may be a more distant show, perhaps something that does not come from our galaxy," says the researcher. "It would be very appealing scientifically!"
Scientists will continue to watch carefully the evolution of these excess UV radiation. One of the Voyager probes, both over 40 years old, is continuing its surveys. The New Horizons probe should reiterate its measurements twice a year. The ship is still on its way, having fulfilled its main objective, the first close flyby of Pluto. Next target: Ultima Thule, a small frozen object in the Kuiper belt that the probe now has in sight. But that's another story ...
F I N .
A glittering hydrogen wall would encompass the Solar System.
By Tristan Vey – Updated on 31/08/2018 at 17:09
Artist's view of the gas bubble enveloping our Solar System and its interactions with the surrounding interstellar gas. NASA / Goddard Space Flight Center, Conceptual Image Lab.
An excess of UV radiation observed by the New Horizons probe, located on the edge of the Solar System, confirms the measurements of the Voyager probes and points to the possible existence of a "hydrogen wall".
What if a "hydrogen wall" emitting a weak ultraviolet radiation enveloped our solar system? This is one of the assumptions made by scientists from the New Horizons mission, whose probe is currently beyond Pluto, who detected a significant excess of photons in this wavelength range. Their results were presented earlier this month in the journal Geophysical Research Letters.
This is not the first time scientists have recorded this strange signal. The two Voyager probes, the first of which officially left the Solar System in 2012, both recorded this surprising excess of ultraviolet radiation more than 30 years ago.
"We are bathing in a very thin cloud of hydrogen lit by the Sun", decrypts Rosine Lallement, a specialist in the interactions between our Sun and the galactic cloud in which we are currently moving. "The Sun excites this hydrogen which starts to" shine "in the UV field. In principle, the further away from the sun, the lower the radiation. Exactly as the halo of light around a street lamp plunged into fog fades with distance. But we had already observed an excess of radiation at the time. And the further we get from the Sun, the better this excess comes out. "
An extragalactic source?
The presence of a hydrogen wall at the edge of our solar system could explain it in part. It is in fact a kind of "bead" formed by the interaction of the gases emitted by the Sun enveloping us (the solar wind) and the interstellar cloud in which we move. A bit like the wave that forms at the front of a boat. The interstellar hydrogen would be in some sort compressed by the "bubble" that surrounds us and accompanies us in our race to 90,000 km / h in the galaxy.
"But the models do not stick well to the observations," warns Rosine Lallement. "There may be an interaction between the ionized gas (electrically charged, that emitted by our star, Editor's note) and the neutral gas (of our galaxy, Ed) that we do not understand well. It's a very interesting problem. "
But there is another hypothesis: that this extra UV radiation comes from even further. "It may be a more distant show, perhaps something that does not come from our galaxy," says the researcher. "It would be very appealing scientifically!"
Scientists will continue to watch carefully the evolution of these excess UV radiation. One of the Voyager probes, both over 40 years old, is continuing its surveys. The New Horizons probe should reiterate its measurements twice a year. The ship is still on its way, having fulfilled its main objective, the first close flyby of Pluto. Next target: Ultima Thule, a small frozen object in the Kuiper belt that the probe now has in sight. But that's another story ...
F I N .
