image:
An artistic representation of what the northern infrared aurora looked like in 2006 (marked in red). Dark red locations indicate confirmed aurora locations, and light red is used to mark potential aurora locations. Credit to NASA, ESA, and M. Showalter (SETI Institute) Background image of Uranus observed with the Hubble Space Telescope (visible spectrum) in August 2005.
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Credit: Credit to NASA, ESA, and M. Showalter (SETI Institute) for the background image of Uranus observed (in the visible spectrum) by the Hubble Space Telescope in August 2005.
Astronomers at the University of Leicester have confirmed the presence of infrared auroras on the cold outer planet of Uranus for the first time.
The discovery could shed light on the mysteries behind the solar system’s planets’ magnetic fields, and even whether life exists on distant worlds.
A team of scientists supported by the Science and Technology Facilities Council (STFC) has obtained the first measurements of Uranus’ infrared (IR) auroras since the study began in 1992. Meanwhile, Uranus’ ultraviolet (UV) auroras have been observed ever since. In 1986, no IR aurora had been confirmed until now.The scientists’ conclusions were published in the journal natural astronomy.
The ice giants Uranus and Neptune are unusual planets in our solar system because their magnetic fields are misaligned with their rotation axes. Scientists have yet to find an explanation for this, but a clue may lie in Uranus’ aurora.
Auroras are caused by high-energy charged particles that funnel down and collide with the planet’s atmosphere via the planet’s magnetic field lines. On Earth, the most famous result of this process is the spectacle of the Northern Lights and Southern Lights. On planets like Uranus, whose atmosphere is mostly a mixture of hydrogen and helium, these auroras emit light at wavelengths outside the visible spectrum and into the infrared (IR).
The research team used infrared auroral measurements obtained by analyzing specific wavelengths of light emitted by the planet using the Keck II telescope. From this, the light from these planets (known as emission lines) can be analyzed, similar to barcodes.In the infrared spectrum, lines emitted by charged particles known as H3+ The brightness changes depending on the temperature of the particles and the density of the atmospheric layers. Therefore, the line acts like a thermometer to the earth.
Their observations revealed a clear increase in H .3+ The density in Uranus’ atmosphere, with little temperature variation, is consistent with ionization caused by the presence of infrared auroras. This could help us better understand the magnetic fields of exoplanets in our own solar system, as well as identify other planets suitable for the presence of life.
Lead author Emma Thomas, a PhD student in the School of Physics and Astronomy at the University of Leicester, said: “The temperatures of all gas giant planets, including Uranus, are hundreds of degrees lower than what models predict they would be if they were simply warmed by Uranus.” above Kelvin/Celsius.” The Sun leaves us with the big question of why these planets are so much hotter than expected? One theory suggests that energetic auroras are responsible for this, with heat generated from the aurora and pushed down towards the magnetic equator.
“The majority of exoplanets discovered to date are classified as subplanetary Neptunes, meaning that they are physically similar in size to Neptune and Uranus. This is because they also have similar magnetic and atmospheric properties. By analyzing Uranus’ auroras, which are directly connected to both the planet’s magnetic field and atmosphere, we may be able to predict the atmospheres and magnetic fields of these worlds, and thus whether they are suitable for life. can.
“This paper is the culmination of 30 years of auroral research on Uranus, finally revealing infrared auroras and beginning a new era of auroral research on this planet. Our results demonstrate that icy giant aurora It will expand our knowledge about and enhance our research’ understanding of planetary magnetic fields in our solar system, exoplanets, and even our own planet. ”
The results may also give scientists insight into a rare phenomenon on Earth, where the north and south poles of a hemisphere swap places, known as geomagnetic reversal.
Emma added: “There hasn’t been much research into this phenomenon, so we don’t know how this will affect systems that rely on the Earth’s magnetic field, such as satellites, communications, and navigation. However, this process is likely to occur when the rotational and magnetic axes It happens every day on Uranus due to a unique shift in polarity. Continued research into Uranus’ auroras is revealing what we can expect when Earth exhibits a polar reversal in the future, and what that means for Earth’s magnetic field. It will provide data about
Article title
Detection of infrared auroras on Uranus with Keck-NIRSPEC
Article publication date
October 23, 2023
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