Welcome to Open Carnage

A resource for gamers and technology enthusiasts, with unique means of rewarding content creation and support. Have a wander to see why we're worth the time!

Krazychic

Scientists Weigh A Star Using Gravity

20 posts in this topic

149691152289972.jpg

 

Albert Einstein's theory of gravity, called general relativity, is probably the best physics theory ever formulated. It just keeps working, often for things Einstein himself didn't believe, like the accelerating expansion of the universe. Scientists only just proved some of its crazy predictions, like gravitational waves.

 

Spoiler

But in the 1930s, Einstein's friend R.W. Mandl visited and asked him to publish on a peculiar prediction of general relativity: That stars should deflect the light that passes by them like a lens would, something we today call gravitational lensing. That paper, published in Science in 1936, said, "Of course, there is no hope of observing this phenomenon directly."

 

But a team of physicists have now measured the mass of a white dwarf star using the way it lensed starlight behind it. Einstein's predictions have once again held true, and his own doubts about his theories have once again been unfounded. And more importantly, scientists have directly measured a single white dwarf star's mass without the help of another star or another model of some kind. They essentially put the star on an interstellar balance scale.

 

"The fact that we could actually measure the mass of a white dwarf is exciting," the paper's lead author, astronomer Kailash Sahu from the Space Telescope Science Institute, told Gizmodo. And "almost all stars go through this white dwarf stage".

 

It's important to note that we've long observed gravitational lensing. In 1919, an experiment led by Sir Arthur Eddington showed the Sun's gravitational field pushing the light of some stars over and around it during a solar eclipse. More recently, deep-field images have uncovered closer galaxies lensing more distant galaxies, and we've even seen stars brighten other stars as they pass in front of them. But measuring the mass of a star by observing the degree to which it bends the light of another star has proven to be an incredibly difficult challenge. Astronomers have to wait for the right conditions, and even then the shift would be incredibly tiny.

 

"It's like if you put a firefly crossing the surface of a US quarter next to a light bulb in New York," said Sahu, "and try to measure the motion of the firefly across that quarter... from Kansas City."

Sahu's firefly is the white dwarf star Stein 2051B — a stellar object around 20 light-years from Earth — which his team observed on several occasions with the Hubble Space Telescope. The star has a partner, Stein 2051A, that it circles from a distance further than that between Earth and Pluto. The team watched as Stein 2015B passed in front of light sources behind it and other random stars, and then measured the apparent shift in the light. They used the data and the relatively simple lensing equation to determine the mass, which aligned nicely with other white dwarf predictions and measurements with other methods. The team published their research in the journal Science today, and presented their results today at the 230th meeting of the American Astronomical Society in Austin, Texas.

 

This isn't the first time scientists have measured the mass of a white dwarf either, but other methods usually require some theoretical model and other measurements or a much closer binary system than this one, astronomer Pier-Emmanuel Tremblay from the University of Warwick in the United Kingdom told Gizmodo. "One could argue this is the most model-independent mass measurement for a single white dwarf," meaning this technique doesn't use assumptions from other fields or observations.

 

None of the scientists I spoke to doubted the importance of the discovery. But everyone asked me to be cautious about overstating the applicability of the method for weighing stars in the future. There's a lot of empty space in this here galaxy, and it's just not that common for a close star to pass a distant star. Despite that, science requires repeated measurements. "I would definitely like to see this method repeated on other objects if possible," professor B. Scott Gaudi from the Ohio State University told Gizmodo. "I think there are a few other good candidates for which this can be done."

 

Sahu already has plans for the future. His team has a catalogue of stars to keep track of, and might be able to measure the mass of our neighbouring star, Proxima Centauri, using this method. But they can't just go measuring everything. "You have to apply for a telescope time, see if the panel thinks it's worth it," he said. "It's a long process."

 

Source

buttonspectre and WaeV like this

Rumors are carried by haters
Spread by fools
and
Accepted by idiots

Share this post


Link to post
Share on other sites

Members of Open Carnage enjoy an ad-free experience!

Stars have a lot of gravity, that is a known fact.  The bigger the star, the more gravity it has.  VY Canis Majoris is 100 times the size of our sun, and therefore has 100 times more gravity.

 

The only exceptions are neutron stars, pulsars and magnetars.  They are all only 10 to 20 miles across, but all have the same gravity as a star.  A sugar cube sized piece of neutron star would weigh 100 MILLION TONNES on Earth, that is how dense they are!

In simple terms, a neutron star, no matter the kind (listed above) are the result of settling just before they turn in to black holes.  A black hole is an area of such concentrated matter in such a small volume that takes up precisely zero space, that nothing can escape is intense gravitational pull, not even light.  In simple terms, stay clear of black holes.


“No, this trick won't work... How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” - Albert Einstein

"For every action has is an equal and opposite reaction". - Sir Isaac Newton
"In honor there is hope" - Alaska State Troopers

Share this post


Link to post
Share on other sites

Stars do not have identical compositions, so you can not extrapolate weight based on size, for any class of star. Additionally, their density goes up as their mass increases (due to gravity), so that further throws off such extrapolations.

buttonspectre and Iggy like this

launched.png

Share this post


Link to post
Share on other sites
6 hours ago, Thomas said:

Stars have a lot of gravity, that is a known fact.  The bigger the star, the more gravity it has.  VY Canis Majoris is 100 times the size of our sun, and therefore has 100 times more gravity.

 

Don't you mean mass?  Also, I think VY Canis Majoris is quite a bit more than 100 times the size of our sun.

002 and Tucker933 like this

oVoXWXc.png

Share this post


Link to post
Share on other sites

Both really.


“No, this trick won't work... How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” - Albert Einstein

"For every action has is an equal and opposite reaction". - Sir Isaac Newton
"In honor there is hope" - Alaska State Troopers

Share this post


Link to post
Share on other sites

There is no source, it's a known fact.  The more massive something has the more gravity it has.  It is what keeps you, me and everyone and everything stuck to the surface of our planet.

tarikja likes this

“No, this trick won't work... How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” - Albert Einstein

"For every action has is an equal and opposite reaction". - Sir Isaac Newton
"In honor there is hope" - Alaska State Troopers

Share this post


Link to post
Share on other sites
1 hour ago, Thomas said:

There is no source, it's a known fact.  The more massive something has the more gravity it has.

Yes, however you need to know the radius of an object as well to calculate gravity... and you said it could all be determined by comparing size, which is incorrect.

 

An increase in mass does increase gravity, however you cannot compare just the mass or just the size of two objects to determine the difference in gravitational force.

buttonspectre likes this

launched.png

Share this post


Link to post
Share on other sites

Posted (edited)

No, that's not exactly what I said.  Let me rephrase:

 

The more massive something is, the more gravity it has.  An object with the mass of a black hole that is packed in to an area so small for example has so much gravity, that nothing, not even light can escape, what we see is the "event horizon" where the point of no return is.  This is  still only a theory, however, it is widely accepted at this point.  If I was someone who was either a degree/Ph.D in physics, I could write one of the longest posts on this board with a dozen calculations that would get your heads spinning!  But I am not anywhere near there just yet.

Edited by Thomas
Corrected a typo...

“No, this trick won't work... How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” - Albert Einstein

"For every action has is an equal and opposite reaction". - Sir Isaac Newton
"In honor there is hope" - Alaska State Troopers

Share this post


Link to post
Share on other sites
8 hours ago, Thomas said:

No, that's not exactly what I said.

You said so here:

On 6/8/2017 at 2:21 AM, Thomas said:

VY Canis Majoris is 100 times the size of our sun, and therefore has 100 times more gravity.

 

buttonspectre likes this

launched.png

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.