Posts Tagged ‘space’

Brown Dwarf

April 29, 2014

Astronomers have recently discovered a previously unknown star only 7.2 light years away. You might wonder how they could miss a star that close to us. Well, Wise J085510.83-071442.5 is not a regular star. It is a brown dwarf, a star that doesn’t actually shine. Here is the story according to the Daily Mail

A brown dwarf star that appears to be the coldest of its kind – as frosty as Earth’s North Pole – has been spotted by an American astronomer.

The discovery was made using Nasa’s Wide-field Infrared Survey Explorer (Wise) and the Spitzer Space Telescope.

Images from the space telescopes also pinpointed the object’s distance at 7.2 light years away, making it the fourth closest system to our sun.

‘It is very exciting to discover a new neighbour of our solar system that is so close,’ said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State and a researcher in the Penn State Center for Exoplanets and Habitable Worlds.

‘In addition, its extreme temperature should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures.’

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight.

The newly-found brown dwarf, named Wise J085510.83-071442.5, is thought to have a chilly temperature between -48°C to -13°C (-54°F to 9°F).

Previous record holders for coldest brown dwarfs, also found by Wise and Spitzer, were about room temperature.

To understand what a brown dwarf actually is, you must realize that like people, stars are born, they live, and eventually they die. A star’s lifespan is measured in eons rather than years and they take little notice of such microscopic mayflies such as we are. A star is born when a massive cloud of gas collapses in on itself. If you recall your high school physics class, you may remember that when a gas is compressed, in this case by the protostar’s gravity, it will heat up. The energy used in compressing the gas is converted into heat. If the protostar’s mass is greater than about .08 solar masses (8% of our Sun), the center of the cloud will become dense enough and hot enough to begin fusing hydrogen into helium. A new star is born. If the mass is less than .08 solar masses than fusion will never begin and the star is stillborn. It becomes a brown dwarf.

Some of the more massive brown dwarves, around 13 to 65 Jupiter masses may fuse deuterium and lithium. They emit mostly infrared radiation. Interestingly, brown dwarves are about the same volume as Jupiter, regardless of their masses. Gravity compresses them to about the same volume. In a way, Jupiter, Saturn, and Neptune could be considered to be very low mass brown dwarves. They emit more energy than they receive from the sun. Perhaps the precise line between a massive planet and a very low mass star is not so easy to define.

General size comparison between a low mass sta...

 (Photo credit: Wikipedia)

A brown dwarf should not be confused with a red dwarf or a white dwarf. A red dwarf is a real star with a mass from about .08 to .5 solar masses. They are small and dim but they do fuse hydrogen in their core and they emit visible light. A white dwarf is a dead star. It has run out of fuel and has collapsed under its own mass until only electron degeneracy, the pressure of electrons crammed together, prevents it from collapsing any further.

But stellar corpses are another topic which I will have to write about another time.

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RIP Neil Armstrong

August 25, 2012

Neil Armstrong died today. I was a little stunned when I read that, but he was 82 and had been having health problems. It is a little sobering to think that his historic footsteps on the Moon happened a lifetime ago, and there still are no plans for humanity to return. I think that the best legacy for Armstrong would have been a continuing American presence in deep space, but it was not to be.

 

We need to get back into the business of exploring the final frontier.

Google Space

April 20, 2012

I just saw this on The Drudge Report. This is the most exciting story I have read in quite a while.

SAN FRANCISCO (Reuters) – Google executive chairman Eric Schmidt and billionaire co-founder Larry Page have teamed up with “Avatar” director James Cameron and other investors to back an ambitious space exploration and natural resources venture, details of which will be unveiled next week.

The fledgling company, called Planetary Resources, will be unveiled at a Tuesday news conference at the Museum of Flight in Seattle, according to a press release issued this week.

Aside from naming some of the company’s high-profile backers, the press release disclosed tantalizingly few details, saying only that the company will combine the sectors of “space exploration and natural resources” in a venture that could add “trillions of dollars to the global GDP.” The Wall Street Journal reported Friday that Planetary Resources will explore the feasibility of mining natural resources from asteroids, a decades-old concept.

“This innovative start-up will create a new industry and a new definition of ‘natural resources,'” according to the press release.

Planetary Resource was co-founded by Eric Anderson, a former NASA Mars mission manager, and Peter Diamandis, the commercial space entrepreneur behind the X-Prize, a competition that offered $10 million to a group that launched a reusable manned spacecraft. Other notable investors include Charles Simonyi, a former top executive at Microsoft, and K. Ram Shriram, a Google director.

The venture will be the latest foray into the far-flung for Cameron, who dived last month in a mini-submarine to the deepest spot in the Mariana Trench. The plot of his 2009 science fiction blockbuster film, “Avatar,” concerned resource mining on alien planets.

It is long past time that the exploration and exploitation of space was opened up to private enterprise. Maybe someday I’ll get to take that vacation on the Moon after all.

Interstellar Travel

October 4, 2011

It has been forty years since man has walked on the moon and it is about time we head out into space again. Some say we should go back to the moon, and maybe set up bases. Others believe a trip to Mars is due. But traveling within our solar system is for stay-at-homes and wimps. We need to go to the stars.

Luckily for us DARPA, the same people who gave us the Internet, are already studying the matter. According to this article in Popular Mechanics, they have organized the 100 year Starship symposium to explore ways to reach the stars. This is no easy matter, of course. The 100 years refers to the amount of time they expect it will take to surmount the difficulties.

The problem of building a starship is so difficult that DARPA’s Tactical Technology Office director and manager for the project, David Neyland, figures it will take 100 years just to learn how to pull it off, hence the project’s name. But while traveling to the stars is a far-off goal, Neyland says that just working on the problem will allow the Department of Defense (of which DARPA is a part) to reap very practical benefits now. “We literally send millions—millions—of MREs, little packaged foodstuffs, to our troops in the field overseas. Is there a better way? Well, if you solve the problem for long-duration, long-distance spaceflight for food supplies, what could you do in terms of the Department of Defense for forward-operating locations?” Solving the problem of energy production on a starship that will have to remain powered up for a decades-long journey could similarly produce major benefits for the military.

Here’s a preview of the enormous problems facing the DARPA conference attendees who dream of interstellar travel. We’ll keep you updated on the wild proposals they come up with to overcome these challenges.

To start with, our rocket technology of the present doesn’t even begin to be effective in traveling such great distances.

It starts with propulsion—simply figuring out how to travel interstellar distances. Chemical rockets, the kind that got us to the moon, just won’t get us to the stars. “You need more fuel than exists mass in the known universe,” says physicist Richard Obousy, president of Icarus Interstellar. Alternatives such as nuclear fission, nuclear fusion, and even antimatter propulsion systems will be on the table here.

 

And of course, there is the difficulty of keeping the crew supplied and motivated for a journey which may take decades or centuries. Any starship we send out will have to be completely self-sufficient. If they break down, no one will be able to rescue them.

I am a little disappointed that star travel is not likely to occur in my lifetime. Perhaps, I should look into cryogenics, have my corpse frozen for later revival.

 

 

 

 

Apollo Moon Landing

July 20, 2011

It’s a good thing I check Instapundit everyday. I didn’t realize that today was the anniversary of the first moon landing until Glenn Reynolds reminded his readers. He put in a link to Apollo images from NASA.

 

 

 

 

 

 

 

 

 

One giant leap.

There were indeed giants in those days. Lesser sons of great sires are we.

Some Anniversaries

April 12, 2011

I just saw that today is the fiftieth anniversary of Yuri Gagarin’s flight. The first man in space. After 50 years, I kind of expected we would sending people to Pluto by now, and colonizing Mars. I must say the future is disappointing.

It is also the 150th anniversary of the Battle of Ft. Sumter, which began the Civil War.


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