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White Dwarfs + Compact Objects – Trottier Institute for Research on Exoplanets



Our Institute’s researchers study more than just exoplanets. In addition to planets and the stars they orbit, our scientists also look at “dead” stars. Sometimes called compact objects or stellar remnants, these are the objects leftover at the end of a star’s life, once it has used up all of its fuel.

Death of a star

The most common type of stellar remnant is a white dwarf, the final fate of more than 97% of the stars in our Galaxy. White dwarfs are created when a small-to-moderately-large sized star burns all of its nuclear fusion fuel, and its core contracts. The outer layers are blown away to create a beautiful planetary nebula, revealing the dense core which has become a white dwarf. Imagine an object with mass similar to our Sun, but compressed down to the size of the Earth. A teaspoon of white dwarf material would weigh as much as three African elephants! This will be the ultimate fate of our own star, the Sun.

An artist’s rendering of an exoplanet orbiting the pulsar PSR B1257+12. (Credit: NASA/JPL-Caltech)

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Neutron stars are even more extreme stellar remnants. They are formed when very large stars run out of fuel. The process begins the same way as for white dwarfs, but in this case, there is too much mass and the contracting core squeezes past the white dwarf stage. The core squeezes down into a ball of pure neutrons.  They can have several times the mass of our Sun, but are only about as large as a city. These are the densest objects we know of, and a small handful of neutron star material on Earth would weigh as much as a mountain!

For the most massive stars, the collapse crushes even the ultra-dense ball of neutrons. These huge stars can turn into black holes when they exhaust their fuel. Black holes are extreme objects that have so much matter packed into such a tiny space that not even light goes fast enough to escape if it wanders too close.

Planets around dead stars?

What do these compact objects have to do with exoplanets? Since stellar remnants were once stars, they may have had planetary systems. They may have even retained their planets after their deaths. In fact, the first exoplanets ever discovered were not found around a regular star, but rather around a neutron star.

There is a special category of neutron stars called pulsars. They get this name because they rotate and pulse radio waves with incredible regularity, making pulsars some of the most stable clocks in the Universe. This regular pulse pattern can wobble slightly if other objects orbit the pulsar.  It was exactly this kind of pulsar wobble that revealed the very first confirmed exoplanet in 1992 around the pulsar PSR 1257+12. This discovery was made by Canadian astronomer Dale Frail (DRAO) and Polish astronomer Aleksander Wolszczan.

Polluted white dwarfs

An artist’s rendering of a destroyed comet around the white dwarf G29-38. (Credit: NASA/JPL-Caltech/GSFC)

White dwarfs provide a very different way of studying exoplanets. One important way that white dwarfs are different from regular stars is their high surface gravity. The gravity on the surface of a white dwarf would make a human weigh millions of kilograms! This causes heavier elements to sink rapidly, leaving a very clean and pure surface of mostly hydrogen and helium. As astronomers studied more white dwarfs, they discovered that some are “polluted” with heavier elements. The only way these heavy elements could be at the surface is if they were recently or continuously deposited there.

How could white dwarfs get polluted atmospheres? As a regular star nears the end of its life and eventually turns into a white dwarf, it can cause gravitational instabilities in its system. Objects such as planets, asteroids, and comets that may have been on stable orbits before the star died might now become unstable. If one of them falls too close to the white dwarf, it can easily be torn apart and form a disc of material that gets accreted onto the surface. Such polluted white dwarfs show us what these shredded objects were made of. This is different from measuring the composition of an exoplanet’s atmosphere, because polluted white dwarfs also reveal the planet’s crust and core materials, not just the atmospheric gasses.

No planets are yet known to exist around black holes, but that doesn’t mean it’s not possible. Researchers are currently looking for signs of planets in systems called x-ray binaries, where a black hole feeds off a stellar companion and emits strong x-rays.

White dwarfs and compact objects at iREx

Many of our iREx researchers are experts on these stellar remnants. Their expertise in these strange objects helps us to study exoplanets in unique ways. To learn more, we invite you to read their profiles:

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NASA's Artemis 1, Over 400,000 Kms From Earth, Sets A New Record – NDTV





New Delhi:

NASA’s Artemis 1 Orion has set a new record for the spacecraft designed to carry humans to deep space by travelling 419,378 kilometres from Earth. The record was previously set during the Apollo 13 mission at 248,655 miles from our home planet.

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For the next six days, Orion will remain in lunar orbit. It will then put the spacecraft on a trajectory back to Earth, followed by a Sunday, December 11, splashdown in the Pacific Ocean, a press release by NASA said.

NASA, in a build-up to the landmark event, said, “Today, NASA Orion Spacecraft will break the record for farthest distance of a spacecraft designed to carry humans to deep space and safely return them to Earth. This record is currently held by Apollo 13.” The text was attached to a video featuring the Apollo astronauts and flight directors who spoke about the future of Artemis. Take a look: 

NASA is expected to use innovative measures to learn more about the Moon’s South Pole. The agency will also try to understand the lunar surface with the help of the Gateway Space Station in orbit, the press note added.  

The spacecraft has a sensor named Commander Moonikin Campos attached to it. It will help provide information on what crew members may experience in flight. The Campos is named after Arturo Campos, the key player in bringing Apollo 13 safely back to Earth. 

Answering questions at a discussion conducted by NASA on Twitter,  Jim Geffre, Orion’s spacecraft integration manager, said,  “Artemis 1 was designed to stress the systems of Orion and we settled on the distant retrograde orbit as a really good way to do that.”

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YouTuber Mark Rober drops eggs from space to land in Victor Valley



Former NASA engineer Mark Rober, the YouTuber best known for his Backyard Squirrel Maze and Exploding Glitter Bomb videos, recently dropped a couple of eggs from space that fell in the Victor Valley.

The 42-year-old Rober and his team of scientists dropped both eggs, with the intention of them not breaking, from a height of nearly 19 miles and with the help of a high-altitude balloon provided by Night Crew Labs.

The launch occurred earlier this year, but the “Egg Drop From Space” video was uploaded to YouTube on Black Friday.

It includes shots of the team driving on Bear Valley Road toward Deadman’s Point in Apple Valley. Also shown are Bell Mountain, Interstate 15 and an area west of I-15 and near the Dale Evans Parkway offramp.

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A shot from the weather balloon in space showed the Victor Valley, including landmarks such as Spring Valley Lake and the Mojave River.

The egg-drop project

When Rober started conceptualizing his egg drop project nearly three years ago, he knew that a successful record drop would come from his experience of landing scientific gear on other planets when he worked for NASA.

A graduate of USC, Rober worked at NASA for nine years, seven of them on the Mars Curiosity project. He also spent five years at Apple working on advanced virtual reality technology for autonomous vehicles before quitting to become a full-time YouTuber.

Rober confessed that before he embarked on the egg drop project, he didn’t know that it would be the most “physically, financially and mentally draining video” he would ever attempt.

The plan

Rober’s team included rocket and propulsion specialist Joe Barnard, of BPS Systems, which helped with the rocket’s guidance system and design.

Rober’s original plan was to affix an egg onto a rocket, which would be lifted by a large weather balloon. Once in space, the rocket would be released and would guide the rocket to an area over the drop target.

At 300 feet above the ground, the egg would be released and free-fall toward a specially designed mattress.

After determining the terminal velocity of the egg to be 74 mph, he successfully tested the speed inside his Crunch Lab located near San Francisco

Rober and his team then headed to the Northern California town of Gridley for three low-altitude tests, which all failed.

‘A fatal flaw’

Rober sought the guidance of NASA engineer Adam Steltzner, who works for the Jet Propulsion Laboratory and on several flight projects including Galileo, Cassini, Mars Pathfinder and the Mars Exploration Rovers.

After listening to Rober and details about his project, Steltzner found a “fatal flaw” in the project and asked him, “How did you not get busted by the FAA?”

Rober realized that his project was akin to creating a precision-guided missile, which is frowned upon by the federal government.

Heading to the High Desert

After going back to the drawing board, Rober’s team decided to conduct a rocket launch with a general egg drop target area in the High Desert.

The launch would use a weather balloon, which would lift a larger and heavier rocket to guarantee the egg would reach supersonic speed on its way down.

The helium-filled balloon would release the rocket, which would begin separating.

A portion of the rocket, carrying the egg, would slow before losing its nose cone and deploying a parachute and cushioned airbags, which were borrowed from the Spirit and Opportunity landing projects.

Just before liftoff, Rober discovered that the newly designed, the two-piece rocket might unexpectedly separate at Mach 2.

Rober and his team fixed the rocket’s connection point and ran vacuum and heat tests on the egg chamber.

They also built redundancy into the system, which included creating a custom beach ball, filled with packing materials to protect a second egg.

The entire payload, suspended from the balloon, would detach and simply fall to earth over the target.

The launch

Rober’s friend, JPL systems engineer Allen Chen, traveled to the Victor Valley for Rober’s second launch.

In 2012, Chen uttered the famous words, “Touchdown confirmed, we’re safe on Mars,” after the Curiosity Rover had survived the harrowing plunge and landed on the red planet.

Somewhere near Apple Valley, the lift-off of Rober’s balloon, rocket, beach ball and eggs was successful.

As the team drove and arrived at the projected landing site, they discovered that the balloon had surpassed the 100,000-foot mark.

As the group celebrated, moments later, they discovered that the balloon had suddenly lost altitude and came crashing down to earth.

As the balloon ascended, the cord that held the rocket, beach ball and eggs had wound so tight that it pulled down on the balloon, causing it to come hurtling down at 150 mph, “Which is way faster than the eggs could survive,” Rober explained.

As the team looked for the wreckage, they spotted the parachute, the rocket and the beach ball.

Rober was excited that at 20,000 feet, the payload had autonomously detached itself from the balloon.

Rober held back his excitement as he opened the rocket to inspect the egg.

As a smiling Rober pulled an uncracked egg from the rocket and held it high, Chen joyously said, “Touchdown confirmed, we’re safe on earth.”

That was repeated when Rober ripped open the beach ball and pulled out a second uncracked egg that he kissed.

“Two for two, baby!” shouted Rober as he high-fived Chen. “Two for two!”

Rober ended the video by saying that the egg drop from space project reminded him that in life things rarely unfold how we think they will.

“But by learning from your failures, coupled with a bit of tenacity, us humans can accomplish a feat as incredible as the world’s smartest Martian robot or as ridiculous as the world’s tallest egg drop,” Rober said.

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In a B.C. first, UVic mini-satellite launched into space after four years of work



A University of Victoria satellite the size of a two-litre milk carton, designed to calibrate light, was fired into space Saturday, after four years of work by dozens of students, faculty and researchers.

ORCASat started its journey to space at 11:20 a.m. Saturday as part of NASA’s SpaceX Falcon 9 rocket launch at Kennedy Space Center in Florida.

Early this morning, about 4 a.m., the satellite is scheduled to be taken on board the International Space Station where it will wait for a few weeks before being fired into space to orbit the Earth for as long as it can survive.

Saturday’s successful launch was extra-sweet because a planned Tuesday launch was postponed due to poor weather. Watchers from UVic returned home after the delayed launch.

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A nervous Alex Doknjas, ORCASat project manager, went into his family’s living room at 10:30 a.m. Saturday where he waited with loved ones and about 20 others on a video chat, including a UVic group, to watch the event together. Cheers and claps erupted when the rocket launched on time. “It’s great. It’s fantastic,” he said.

There was a little wind picking up on the launch site shortly before liftoff was scheduled and Doknjas said he was worried it was about to get scrubbed again, but that didn’t happen.

The excitement has been years in the making thanks to about 140 people who have been part of a team at the University of Victoria Centre for Aerospace Research.

Full-time researchers, co-op and volunteer students from UVic Satellite Design, UBC Orbit, and Simon Fraser University Satellite Design have all contributed.

The ORCASat (for Optical Reference Calibration Satellite) measures 10 centimetres by 10 centimetres by 23 centimetres and weighs 2.5 kilograms.

Doknjas said as far as he knows this is the first “Cubesat” designed and built in this province. “That’s a pretty big milestone.”

The estimated date to launch ORCASat is between Dec. 29 and the first week in January.

ORCASat will be doing a 400-kilometre orbit around Earth and travelling at 7.5 kilometres a second. “It’s pretty fast.”

It is not known exactly how long it will last but it could be six to eight months, up to 18 months, Doknjas said. Factors such as sun flares, solar radiation, pressure and more can all impact the life of the satellite.

ORCASat is basically an artificial star, a reference light source in orbit that can be viewed by telescopes on Earth.

Astronomers can measure how bright ORCASat appears, just as they would an astronomical object.

At the same time, the satellite, using two laser light sources, will measure the amount of light that an astronomical object is emitting.

This will allow ground-based telescopes to be calibrated to measure the absolute brightness of an astronomical object, not how they appear after passing through the atmosphere and the optics of a telescope.

This is the first satellite ever to carry a light source capable of performing this experiment to this level of accuracy.

It is a proof-of-concept technology which in the future could be developed to be applicable in such areas as climate change, Earth observation and methane gas research, Doknjas said.


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