Approximately 4.1 to 3.8 billion years ago, the planets of the inner Solar System experienced many impacts from comets and asteroids that originated in the outer Solar System. This is known as the Late Heavy Bombardment (LHB) period when (according to theory) the migration of the giant planets kicked asteroids and comets out of their regular orbits, sending them hurtling towards Mercury, Venus, Earth, and Mars. This bombardment is believed to have distributed water to the inner Solar System and maybe the building blocks of life itself.
According to new research from the University of Cambridge, comets must travel slowly – below 15 km/s (9.32 mi/s) – to deliver organic material onto other planets. Otherwise, the essential molecules would not survive the high speed and temperatures generated by atmospheric entry and impact. As the researchers found, such comets are only likely to occur in tightly bound systems where planets orbit closely to each other. Their results show that these systems would be a good place to look for evidence of life (biosignatures) beyond the Solar System.
The research was conducted by Richard Anslow and Amy Bonsor, a Ph.D. Student and a Royal Society University Research Fellow from the Institute of Astronomy at the University of Cambridge (respectively). They were joined by Paul Rimmer, an SCOL Senior Fellow with the Cavendish Laboratory’s Astrophysics Group at the University of Cambridge. Their paper, titled “Can comets deliver prebiotic molecules to rocky exoplanets?” appeared on November 15th in the Proceedings of the Royal Society A.
The many tails of Comet 73P. Credit and copyright: Michael Jaeger.
In our Solar System, most comets originate in the Kuiper Belt, the circumstellar disk extending 30 astronomical units (AUs) – beyond Neptune’s orbit – to approximately 50 AU. When Kuiper Belt objects (KBOs) collide, they can get “kicked” by Neptune’s gravity towards the Sun, eventually getting captured by Jupiter’s gravity. Some of these comets will then be hurled past the Asteroid Belt and make their way into the inner Solar System. These comments will grow “tails” as they approach the Sun as rising temperatures cause their frozen volatiles to sublimate.
Scientists have also learned that comets can contain prebiotic molecules, which are the building blocks of life. This includes hydrogen cyanide, methanol, formaldehyde, ethanol, ethane, and more complex molecules like long-chain hydrocarbons and amino acids. For example, samples returned from the Ryugu asteroid in 2022 showed evidence of intact amino acids and nicotinic acid, an organic molecule otherwise known as vitamin B3. However, not all these elements can remain intact when entering a planet’s atmosphere and hitting the surface. As Anslow said in a University of Manchester press release:
“We’re learning more about the atmospheres of exoplanets all the time, so we wanted to see if there are planets where complex molecules could also be delivered by comets. It’s possible that the molecules that led to life on Earth came from comets, so the same could be true for planets elsewhere in the galaxy.
“We wanted to test our theories on planets that are similar to our own, as Earth is currently our only example of a planet that supports life. What kinds of comets, traveling at what kinds of speed, could deliver intact prebiotic molecules? In these tightly packed systems, each planet has a chance to interact with and trap a comet. It’s possible that this mechanism could be how prebiotic molecules end up on planets.”
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15 Years of Data Reveal the Events Leading Up to Betelgeuse’s “Great Dimming”
Anyone who regularly watches the skies may well be familiar with the constellation Orion the hunter. It is one of the few constellations that actually looks like the thing it is supposed to look like rather than some abstract resemblance. One prominent star is Betelgeuse and back in 2020 it dimmed to a level lower than ever before in recorded history. A team of astronomers have been studying the event with some fascinating results.
Betelgeuse is a red supergiant star almost 650 light years from Earth. With a radius of 617 million kilometres, if it were in the position of the Sun, then the orbit of Earth would be buried deep within its layers. It’s also a variable star which means it varies its output of light and in the case of Betelgeuse this variability is semi-regular or in other words, regular with a few irregularities along the way! Its variability is related to a pulsating of the stars radius which occurs over a period of around 400 days although there is a longer period of variability of around 2,100 days of uncertain origin, possibly linked to variation in convective flow.
Back in 2020 Betelgeuse dimmed to a level that had never been recorded in what has since been dubbed the “Great Dimming”. It’s visual brightness or magnitude, dropped by 1.6 although its dimming did not seem consistent across the star’s sphere; the southern hemisphere was much darker than the northern and there have been many theories put forward to explain the event. Among them, large formations of star spots or dust clouds above the photosphere are favourite.
A paper published recently in Astronomy and Astrophysics by a team of astronomers led by Daniel Jadlovský explores the Great Dimming event using 15 years of data from the STELLA robotic telescope. The STELLA system comprises two robotic telescopes in Spain coupled with a high resolution spectrograph and a wide field imager.
STELLA Observatory in Tenerife, Spain.
The data allowed the team to explore the photosphere (visible layer) of Betelgeuse in incredible detail. They were able to gain valuable insight into the radial pulsations, shockwaves and how they passed through the photospheric layers. Five distinct layers of the photosphere were identified using the tomogrpahic technique – a method where images are constructed form a series of projections.
Analysis revealed that the variations in the innermost photospheric layer, known as C1 was in line with the timescales of the visual magnitude variations. Shockwaves travelling through the layers also seemed to be broadly in line with the brightness variations. In regards to the Great Dimming vent of 2020, the data showed two powerful shock waves in the photosphere, the first likely to be the cause of a major outflowing of material which caused an infall of all layers. As the infall reached maximum velocity the second, more powerful shockwave occurred leading to the a significant outflow of material. Due to the different photospheric layers, these events didn’t happen simultaneously across them all and it wasn’t until early 2022 that Betelgeuse settled back down.
Source : The Great Dimming of Betelgeuse: the photosphere as revealed by tomography during the past 15 years
The post 15 Years of Data Reveal the Events Leading Up to Betelgeuse’s “Great Dimming” appeared first on Universe Today.
Iran Sent a Capsule Capable of Holding Animals into Orbit.
Despite popular opinion, the first animals in space were not dogs or chimps, they were fruit flies launched by the United States in February 1947. The Soviet Union launched Laika, the first dog into space in November 1957 and now, it seems Iran is getting in on the act. A 500kg capsule known as the “indigenous bio-capsule” with life support capability was recently launched atop the Iranian “Salman” rocket. It has been reported by some agencies that there were animals on board but no official statement has been released.
The Iranian Space Agency (ISA) are gearing up to getting humans into space before 2029 but is testing its launch capability with animal passengers. The capsule was launched on December 6 2023 and attained an orbital altitude of 130 kilometres. According to their Telecommunications Minister Isa Zarepour, it is aimed at sending Iranian astronauts to space by 2029.
The “Salaman” solid-fuelled rocket was designed by the aerospace division of the Ministry of Science, Research and Technology and built and launched by the Ministry of Defence and Armed Forces Logistics. It has already been used to launch a data collecting satellite and in 2013 successfully sent and returned monkeys into space.
Ham, a chimpanzee, became the first great ape in space during his January 31, 1961, suborbital flight aboard Mercury-Redstone 2 (Credit : NASA)
To date, only three counties have human spaceflight capability; USA, Russia and China. India are attempting to become the fourth as they work on their Gaganyaan program. Will Iran become the fifth!? Iran plans further tests with further launches bearing animal occupants before attempting to send humans up.
According to the Iranian Space Agency, its satellite program is purely for scientific research and other civilian applications. There is however, international suspicion because there are suspicions that the Salamn rockets could very easily be converted to long range missiles.
Source : Iran says it sent a capsule capable of carrying animals into orbit as it prepares for human missions
The post Iran Sent a Capsule Capable of Holding Animals into Orbit. appeared first on Universe Today.
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What Could a Next Generation Event Horizon Telescope Do?
Telescopes have come a long way in a little over four hundred years! It was 1608 that Dutch spectacle maker Hans Lippershey who was said to be working with a case of myopia and, in working with lenses discovered the magnifying powers if arranged in certain configurations. Now, centuries on and we have many different telescope designs and even telescopes in orbit but none are more incredible than the Event Horizon Telescope (EHT). Images las year revealed the supermassive black hole at the centre of our Galaxy and around M87 but now a team of astronomers have explored the potential of an even more powerful system the Next Generation EHT (ngEHT).
There is no doubt that our understanding of the processes within our Universe have come on leaps and bounds since the invention of the telescope. The resolution of these space piercing instruments is dictated by the telescope’s aperture. The technique known as interferometry hooks individual telescopes together and combines their signal so they act as one BIG telescope, boosting the resolution.
Telescopes like the EHT have been using interferometry to great advantage to study black holes. These enigmatic and mysterious stellar corpses defy our probing; we do not fully understand their origins and processes and indeed our laws of physics break down if you get too close to the point source in the centre, the singularity. Due to their interaction with space and time, understanding the full nature of black holes will – hopefully – unlock our understanding of the Universe.
Previously, observations have only revealed the movement of stars around galactic centre suggesting an object was lurking there weighing in at around 4 million times the mass of the Sun. Data from the EHT collected during 2022, finally revealed an image of the object at the centre – SgrA* – a super massive black hole and the matter in the immediate vicinity of the event horizon. Whilst this image did not reveal the black hole itself – another article required to explain that – it certainly revealed the telltale signs.
Sag A* compared to M87* and the orbit of Mercury. Credit: EHT collaboration
A recently published paper explores the possibilities of the ngEHT and how they might be able to unpick some of the physics around black holes. The ngEHT will increase the geographical footprint of EHT by 10 further instruments that span across the Earth. Making use of the significant improvement in resolution, the ngEHT will also improve image dynamics range, provide a multi-wavelength capability and facilitate long term monitoring.
The team conclude that future enhancements in measurement sensitivity and data analysis techniques in ngEHT will substantially advance our understanding of black holes and the immediate environments surrounding them with particular focus on the photon ring, mass and spin analysis, binary supermassive black holes and more besides.
Source : Fundamental Physics Opportunities with the Next-Generation Event Horizon Telescope
The post What Could a Next Generation Event Horizon Telescope Do? appeared first on Universe Today.
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