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#198 - Exodus Orbitals - Light-speed stars

This week we have a chat with Dennis Silin from startup Exodus Orbitals. We discuss the fastest stars in the galaxy and the super close ocean world that was there all along!


available August 14th

"You are the best at being you (and not someone else) and are at your best when what you do makes you happy. Great is what you’ll be and confidence is the bag you carry it in"

Tracy “TC” Caldwell Dyson Born OTD 14th August


The first astronaut who was born after Apollo 11, inspired by Christa McAuliffe to become an astronaut and potentially could be the first person to step back on the moon. She shares lead vocal duties in the band MAXQ with Drew Feustel, Dan Burbank, Chris Hadfield and Dottie Metcalf-Lindengburger


Happy Birthday!!!








Shout out to The Two Justins

Justin Roberts here in the UK and Justin Young astrophotography legend out in Tazmania.

Patreon Legends! ...You could always join them.


Dennis Silin from Exodus Orbitals, joins us to tell about Nova and much more.



Filk Music








Songs for the Space playlist from the FILK genre.








News

Arecibo Observatory: Puerto Rico A 3 inch cable has severely damaged the Arecibo Dish. The cable supporting the receiver platform broke, causing a 100-foot-long gash on the reflector dish


If you are wondering what it looks like, it appears in lots of Films, Piers Brosnan has a fight on it in Goldeneye and it is heavily featured in the Film Contact with Jodie Foster.



It’s really only just recovering from the storm (Hurricane Maria) that hit it in 2017


The 3-inch cable snapped and fell ripping a gash in the dome (6-8 of the 38,778 aluminium panels),. The main collecting dish was the world’s largest single-dish radio telescope, until the stupidly big FAST in China. . The reflective dish is 1,000 feet in diameter, 167 feet deep, and covers an area of about 20 acres.



It’s built-in a sinkhole and stuff grows underneath the dish still. It’s a spherical dish due to its type of operation, moving the receiver above and obviously the dish doesn’t move so if you have a parabolic dish you would get weird astigmatism spending on where you put the receiver.

Built in the 60’s - Used to

1964: Determine the rotation period of Mercury as 88 days, not 59 as previously thought

1968, the discovery of the periodicity of the Crab Pulsar (33 milliseconds) by Lovelace and others provided the first solid evidence that neutron stars exist

1974 Hulse and Taylor used it for their Nobel prize-winning discovery of a binary pulsar

1989: Imaged an asteroid, first direct image ever, 4769 Castalia

1990: Discovered the first exoplanets.with the observation of the discovery of pulsar PSR B1257+12

In 1974, the Arecibo Message, an attempt to communicate with potential extraterrestrial life, was transmitted from the radio telescope toward the globular cluster Messier 13, about 25,000 light-years away

The telescope also originally had military intelligence uses, including locating Soviet radar installations by detecting their signals bouncing off the Moon


Space Word of The Week: Squeezars

Back in 2003 Tal Alexander and Mark Morris wrote a paper Squeezars: Tidally Powered Stars Orbiting a Massive Black Hole

Stars caught in highly eccentric orbits around a massive black hole (MBH) have atypically high luminosity powered by tidal interactions with the MBH.

They suggested two flavours: surface heating with radiative cooling ("hot squeezars") and bulk heating with adiabatic expansion ("cold squeezars")

Fast forward 17 years!


S62 and S4711: Indications of a Population of Faint Fast-moving Stars inside the S2 Orbit—S4711 on a 7.6 yr Orbit around Sgr A*

Florian Peißker1, Andreas Eckart et al University of Cologne in Germany


When they say fast-moving, they really do mean fast-moving, the Star S4714 looks like at some points it’s is going 8% the speed of light ...the fastest star in the Milkyway!!! 15,000 miles per second, it can get around the earth in slightly under 2 seconds!!!


So there are a bunch of stars in crazy orbits, that pretty much prove we have a Supermassive Black Hole at the centre of the Galaxy Sgr A*. Roughly 4 million times more massive than the sun!! With a ridiculous event horizon radius of 17 times that of the sun!!! About 0.1 AU. 25,640 light-years away. In an area about the size of our solar system instead of planets and comets, the Blackhole has stars orbiting in a much more extreme version.


Star S4714 is part of a cluster of 5 stars it is on a very eccentric orbit. Eccentricity is on a scale of 0 (circle) to 1 (escape). S4711 is 0.985! So borderline being flung out of the system. It orbits every 12 years swooping in like a comet going around the sun at insane speeds, getting very close to the Blackhole at the periapses and almost slowing down to nothing at the apoapsis

It actually gets about as close as the somewhere between Saturn and Uranus form from the sun. then swings out to



Another star S4711 is also on a highly eccentric orbit but only on a 7,6-year orbit, sizzling past the Blackhole at only 144 AU, And going a whopping 6.7 % the speed of light! But on average this star is the closest to the BH.


But obviously these stars coming that close to the BH are going to be perfect candidates to test for Squeezars. What should happen is as they get close the BH squeezes them and the tidal forces will be converted into energy brightening the star, but also this borrowing of energy from the tide will be slowing the star down and decaying the orbit, these stars are doomed!!!


They are also going to be helpful for testing General relativity. One of the famous stars in the area S2 was used to test GR, as the conditions are so extreme, but these are closer and moving faster. So when a replacement for ESO Sinfoni (Spectrograph for INtegral Field Observations in the Near Infrared) these will make an even better test.

Expect may more stories of super-fast stars in this area as the big telescopes come online.



The World Ceres (thanks to Mark Scheuern ...for that pun)

Heap of papers in Nature.

Discovered in 1801 dwarf planet Ceres is the largest object in the main asteroid belt that lies between the orbits of Mars and Jupiter, 25th largest body in the solar system at 580miles across. Rounded by its own mass Ceres comprises 25% of the asteroid belt's total mass, Pluto is still 14 times more massive



The robotic NASA spacecraft Dawn entered orbit around Ceres on 6 March 2015, after making a trip via the other big asteroid Vesta (9% of the asteroid belt mass) making it the first probe to get into orbit of two separate bodies, using it’s revolutionary ion engines. 5.9 years of ion engine runtime.



As Dawn approached Ceres it was obvious that a feature was going to dominate the news, what on earth was this white spot!! ...or spots.. Dawn captured images of two distinct, highly reflective areas within Occator Crater, which were subsequently named Cerealia Faculae and Vinalia Faculae.



Dawn got closer and into orbit and actually managed to get within 22 miles of the surface, and revealed the white spots to be pink as well. Scientists worked out that these spots were salt crystals. Saltwater had seeped out of the planet and evaporated leaving behind Sodium Carbonates with a highly reflective surface. This reflective surface must be very young as micrometeorite should have dulled the surface over any long time period. Where was this salty broth coming from?



In fact, that was some wetness still, so water is still seeping up, Occator is an impact crater, the heat form this impact caused the ice to melt about 20 million years ago and caused some of the material at the top as the heat died down, this process must have stopped, but cracks and fractures have managed to link up with a long-lived reservoir of brine to percolate up to the surface. Studying Ceres' gravity, scientists learned more about the dwarf planet's internal structure and were able to determine that the brine reservoir is about 25 miles (40 kilometres) deep and hundreds of miles wide.

Plenty of other features like small mounds and hills show a post-impact Cryo-Hhydrrologic formation. one team discovered the presence of the compound hydrohalite -- a material common in sea ice but which until now had never been observed off of Earth.

Bottom line Ceres is an ocean world ...the solar system just got even more interesting. I suspect Ceres will be more actively discussed as a potential home for microbial extraterrestrial life like Mars, Europa, Enceladus, or Titan, t The remote detection of organic compounds and the presence of water with 20% carbon by mass in its near-surface, conditions favourable to organic chemistry




Shout out to the Legends

Dr Bob “Vultan” Hodges

John “The Explorere” Benac

Kaarel “The Tallinn Talent” Siim

Julio “Homme fusée” Aprea

Dr Kenton “neuroscientist” Hokanson

Darren “the law” Fooks

Ronald “man of Kent” Hatcher

Merissa “star dreamer” Davis

Patrick “PH” Haywood

Tupper “no socks” Hyde

Malte “the Gecko” Kiebling

Rob “habitats” Annable

Stas “source code” Shusha

Mark “bleeping” Scheuern

Christopher “historian” Andreasen

Audun “the tech guy” Vaaler

Antony “The Stalwart Engineer” Peggs

Bob “I could not like him more” Moore



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