This was adopted by the spacecraft making the first-ever encounter with a Kuiper Belt Object (KBO) – often known as Arrokoth (AKA 2014 MU69) – on 31 December 2018. As well as, its distinctive place within the outer Photo voltaic System has allowed astronomers to conduct uncommon and profitable science operations.
This has included parallax measurements of Proxima Centauri and Wolf 359, the 2 closest stars to the Photo voltaic System.
As well as, a group of astronomers led by the National Optical Astronomy Observatory (NOAO) and Southwest Research Institute (SwRI) used archival knowledge from the probe’s Long Range Reconnaissance Imager (LORRI) to conduct measurements of the Cosmic Optical Background (COB).
The research, which was not too long ago accepted for publication by The Astrophysical Journal, was led by Tod R. Lauer of the NOAO. He was joined by Alan Stern (the PI of the New Horizons mission) and researchers from the SwRI, NASA, the Johns Hopkins College Utilized Physics Laboratory (JHUAPL), the Area Telescope Science Institute (STSI), the Lunar and Planetary Institute (LPI), the SETI Institute, and a number of universities and establishments.
Put merely, the COB is the sunshine from all sources exterior the Milky Means that’s unfold diffusely all through the observable Universe.
On this sense, it’s the seen mild analogue of the Cosmic Microwave Background (CMB), and is a crucial benchmark for astronomers. By measuring this mild, they’re able to discern the places of stars, the dimensions and density of galaxies, and take a look at theories in regards to the construction and formation of the cosmos.
Precisely measuring the COB is essential for a number of causes. For starters, this background is integral to the historical past of star formation, star clusters, galaxies, black holes, galaxy clusters, and the massive scale construction of the Universe.
Due to this fact, understanding precisely how darkish the night time sky is can present perception into the formation and evolution of the Universe.
As well as, astronomers have sought to find out if there was a diffuse part to the COB (dCOB), a supply of photons not related to any presently recognized objects.
The presence of such a part would enable astronomers to check how a lot of the cosmic background mild may very well be coming from objects within the low-density areas of the Universe, or objects that fashioned previous to the Universe organizing into its present patterns.
A dCOB may additionally replicate the manufacturing of photons by extra unique processes, such because the annihilation or decay of dark matter particles – due to this fact aiding within the ongoing seek for this “invisible” mass.
Sadly, a majority of these research current quite a few challenges since Earth-based telescopes are topic to atmospheric distortion and space-based telescopes should take care of interference from Zodiacal Light.
Consequently, there have been critical discrepancies within the inferred brightness of the optical background over time.
However for spacecraft within the outer Photo voltaic System, a majority of these interference are usually not an issue. Therefore why astronomers have relied on all earlier missions that ventured past Neptune to conduct COB measurements – i.e. the Pioneer 10/11 and Voyager 1/2 missions.
Equally, the Hubble Area Telescope additionally performed measurements of the COB, however these had been restricted in comparison with what New Horizons was capable of witness.
As Lauer, who’s a former member of the Hubble Wide Field and Planetary Camera group, advised Universe In the present day by way of electronic mail:
“NH can cleanly measure the full mild flux emitted by the distant Universe. The Hubble is excellent at including up all of the distant galaxies, however does much less effectively for stuff not in galaxies that makes a diffuse background, which will get twisted up with the scattered daylight bounced round by mud within the close to Earth atmosphere.”
Apparently, this isn’t the primary time that astronomers have used LORRI knowledge to measure the COB.
In 2017, a NASA-led group examined LORRI knowledge from 4 totally different remoted sky fields that had been imaged between 2007 and 2010. This coincided with the NH’s cruise section the place it handed between the orbits of Jupiter and Uranus.
For the sake of this research, Lauer and his group examined brightness ranges noticed by LORRI of seven excessive galactic latitude fields when the New Horizons mission was 42 to 45 AU from the Solar.
At this distance, the common uncooked mild ranges had been 10 instances darker than what Hubble was capable of observe. After correcting for any remaining interference, the group ran a Monte Carlo simulation to mannequin potential sources of sunshine.
From this, they had been capable of discern the presence of a diffuse part of unknown origin, presumably brought on by the presence of faint galaxies that stay undetected.
As Lauer and his colleagues concluded, this might recommend that the present census on faint galaxies falls quick and at the least half of these with an obvious magnitude stage of 30 or extra are unaccounted for.
This isn’t the primary occasion in recent times when the galactic census has needed to be revised. Till a couple of years in the past, astronomers had been of the overall consensus that there have been 200 billion galaxies within the observable Universe.
This was based mostly on the Hubble Ultra Deep Field commentary marketing campaign, from which astronomers created detailed 3D maps of the Universe.
However on revised calculations in 2016, astronomers now estimate that there are as many as two trillion galaxies within the observable Universe. Primarily based on these newest outcomes, it seems as if the depend would possibly must be up to date once more.
Regardless, the work of Lauer and his colleagues demonstrates the utility of missions like New Horizons and the sorts of analysis they will carry out within the outer Photo voltaic System.