Gravity-bending find leads to Kepler meeting Einstein

Apr 04, 2013
This artist's concept depicts a dense, dead star called a white dwarf crossing in front of a small, red star. The white dwarf's gravity is so great it bends and magnifies light from the red star. Image credit: NASA/JPL-Caltech

(Phys.org) —NASA's Kepler space telescope has witnessed the effects of a dead star bending the light of its companion star. The findings are among the first detections of this phenomenon—a result of Einstein's theory of general relativity—in binary, or double, star systems.

The , called a white dwarf, is the burnt-out core of what used to be a star like our sun. It is locked in an orbiting dance with its partner, a small "" star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive.

"This white dwarf is about the size of Earth but has the ," said Phil Muirhead of the California Institute of Technology, Pasadena, lead author of the findings to be published April 20 in the Astrophysical Journal. "It's so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf."

Kepler's primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler's sensitive detectors can see.

"The technique is equivalent to spotting a flea on a light bulb 3,000 miles away, roughly the distance from Los Angeles to New York City," said Avi Shporer, co-author of the study, also of Caltech.

This chart shows data from NASA's Kepler space telescope, which looks for planets by monitoring changes in the brightness of stars. As planets orbit in front of a star, they block the starlight, causing periodic dips. The plot on the left shows data collected by Kepler for a star called KOI-256, which is a small red dwarf. At first, astronomers thought the dip in starlight was due to a large planet passing in front of the star. But certain clues, such as the sharpness of the dip, indicated it was actually a white dwarf -- the dense, heavy remains of a star that was once like our sun. In fact, in the data shown at left, the white dwarf is passing behind the red dwarf, an event referred to as a secondary eclipse. The change in brightness is a result of the total light of the system dropping. Image credit: NASA/Ames/JPL-Caltech

Muirhead and his colleagues regularly use public Kepler data to search for and confirm planets around smaller stars, the red dwarfs, also known as M dwarfs. These stars are cooler and redder than our yellow sun. When the team first looked at the Kepler data for a target called KOI-256, they thought they were looking at a huge eclipsing the red dwarf.

"We saw what appeared to be huge dips in the light from the star, and suspected it was from a giant planet, roughly the size of Jupiter, passing in front," said Muirhead.

To learn more about the star system, Muirhead and his colleagues turned to the Hale Telescope at near San Diego. Using a technique called radial velocity, they discovered that the red dwarf was wobbling around like a spinning top. The wobble was far too big to be caused by the tug of a planet. That is when they knew they were looking at a massive white dwarf passing behind the red dwarf, rather than a gas giant passing in front.

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Dead Star Warps Light of Red Star

The team also incorporated ultraviolet measurements of KOI-256 taken by the Galaxy Evolution Explorer (GALEX), a NASA now operated by the California Institute of Technology in Pasadena. The GALEX observations, led by Cornell University, Ithaca, N.Y., are part of an ongoing program to measure ultraviolet activity in all the stars in Kepler field of view, an indicator of potential habitability for planets in the systems. These data revealed the red dwarf is very active, consistent with being "spun-up" by the orbit of the more massive white dwarf.

The astronomers then went back to the Kepler data and were surprised by what they saw. When the white dwarf passed in front of its star, its gravity caused the starlight to bend and brighten by measurable effects.

"Only Kepler could detect this tiny, tiny effect," said Doug Hudgins, the Kepler program scientist at NASA Headquarters, Washington. "But with this detection, we are witnessing Einstein's theory of general relativity at play in a far-flung star system."

One of the consequences of Einstein's is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, in our galaxy and beyond. For example, the light from a distant galaxy can be bent and magnified by matter in front of it. This reveals new information about dark matter and dark energy, two mysterious ingredients in our universe.

Gravitational lensing has also been used to discover new planets and hunt for free-floating planets.

In the new Kepler study, scientists used the gravitational lensing to determine the mass of the white dwarf. By combining this information with all the data they acquired, the scientists were also able to measure accurately the mass of the red dwarf and the physical sizes of both stars. Kepler's data and Einstein's theory of relativity have together led to a better understanding of how binary stars evolve.

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More information: Paper: dx.doi.org/10.1088/0004-637X/767/2/111

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vacuum-mechanics
1 / 5 (13) Apr 04, 2013
One of the consequences of Einstein's theory of general relativity is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, in our galaxy and beyond. For example, the light from a distant galaxy can be bent and magnified by matter in front of it. This reveals new information about dark matter and dark energy, two mysterious ingredients in our universe.

This is the familiar conventional explanation which said that curve space make the bending of light path, but the problem is that according to the theory, space is empty so how empty space could be curved! Maybe this simple physical view could help us to understand it.
http://www.vacuum...18〈=en
Silverhill
5 / 5 (7) Apr 04, 2013
How can empty space be curved? The equations that most accurately describe the locations of objects, and their paths, have solutions whose graphs require curvilinear coordinates rather than flat, straight Euclidean/Cartesian coordinates.
ValeriaT
1 / 5 (9) Apr 04, 2013
In the ancient deDuillier/LeSage theory of gravity the massive objects are violating the balance between transverse and longitudinal waves in vacuum with shielding of longitudinal waves. This is essentially a large distance analogy of Cassimir force. You may imagine the massive body like the ball floating at the water, while both underwater both surface are full of waves. The shielding of ripples (Brownian noise) around sphere corresponds the Cassimir force and the shielding of underwater waves corresponds the gravity. Because the underwater sound waves are (spreading) way faster, than the surface ripples, their shielding manifest itself at much larger distance, but the principle remains the very same. The excess of surface ripples manifests itself like the positive net curvature of water surface (the surface ripples are doing it more expanded), the excess of underwater waves like the negative net curvature of water surface.
ValeriaT
1 / 5 (9) Apr 04, 2013
It should be pointed out, that the LeSage shielding model leads into inverse square law in very straightforward way (which indicates, it's actually the primary mechanism of gravity) - whereas the general relativity doesn't derive/explain it at all. Instead of it it uses the gravitational law on background as such during derivation of stress energy tensor from metric tensor. In this sense we can say, despite the general relativity is understood like the extension of Newton law from macroscopic perspective, it's still relies on it its full depth locally. Every local violation of Newton law would therefore lead into violation of general relativity with no mercy.
inglenook_hampendick
1 / 5 (4) Apr 04, 2013
heat can bend light too. just look at hot air rising off asphalt. Are scientists taking that into account?
Silverhill
5 / 5 (4) Apr 05, 2013
Scientists have already taken into account the refraction of light waves through lower-density media such as heated air....
vlaaing peerd
5 / 5 (3) Apr 05, 2013
ValeriaT

There is no large scale analogy possible of Casimir force. For that you need massive amounts of energy or mass to flip in and out of existence, it just doesn't happen mate.

I'm fine with you posting all these ideas, but stay consistent in it and allow yourself to admit there are some serious flaws in it.
dschlink
not rated yet Apr 05, 2013
A good write-up and I really appreciate the 'enlarge' being big enough to actually see.
Fleetfoot
5 / 5 (3) Apr 05, 2013
heat can bend light too. just look at hot air rising off asphalt. Are scientists taking that into account?


The heat causes the air to expand and become less dense. Bubbles of warm, thin air then act like lenses. The white dwarf is surrounded by near vacuum so although the same effect happens, it is much too small to be measurable. For the Sun, it's thousands to millions of times less than the gravitational effect (depending on the wavelength measured), for the white dwarf probably even more so due to the higher surface gravity.
Q-Star
1 / 5 (2) Apr 05, 2013
heat can bend light too. just look at hot air rising off asphalt. Are scientists taking that into account?


The heat causes the air to expand and become less dense. Bubbles of warm, thin air then act like lenses. The white dwarf is surrounded by near vacuum so although the same effect happens, it is much too small to be measurable. For the Sun, it's thousands to millions of times less than the gravitational effect (depending on the wavelength measured), for the white dwarf probably even more so due to the higher surface gravity.


Additionally, the refraction of light in a heated gas tends to bend in random directions, gas is a chaotic environment for a photon to travel through regardless of temperature, that's why fine detail microscopy is done with a stable medium, such as oil or glycerine between the object being viewed & the objective lens.

The reason that adaptive optics took so long to develop was due to the shear numbers of random corrections/time necessary
GSwift7
5 / 5 (1) Apr 05, 2013
Additionally, the refraction of light in a heated gas tends to bend in random directions


Refracted light passing through the atmosphere of the white dwarf would be essentially zero here. As with any planet, including Earth, the thickness of the atmosphere is so small that it can be ignored when viewed from a distance. For example, when you look at images of Jupiter, it's edges appear solid. Background objects like stars do not visibly waver in Jupiter's atmosphere as they pass behind. The relative thickness of the effect is too small to be observable and may be ignored.

Besides, even with such an effect, without gravitational lensing, the net effect on the total light of the system would be negative as the white dwarf passes in front of its friend, not positive. In this case, the white dwarf is actually bending light towards our direction which otherwise would not have been headed our way.
Fleetfoot
5 / 5 (1) Apr 05, 2013
It should be pointed out, that the LeSage shielding model leads into inverse square law ...


It should also be pointed out for any laymen browsing through that since we know the inverse square law is wrong, so was that model.

Further, it would deposit so much heat into any mass that it would be vapourised in a fraction of a second. The Earth would be raised to billions of degrees in a microsecond for any non-falsified values that would produce normal Earth surface gravity.
aroc91
not rated yet Apr 07, 2013
One of the consequences of Einstein's theory of general relativity is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, in our galaxy and beyond. For example, the light from a distant galaxy can be bent and magnified by matter in front of it. This reveals new information about dark matter and dark energy, two mysterious ingredients in our universe.

This is the familiar conventional explanation which said that curve space make the bending of light path, but the problem is that according to the theory, space is empty so how empty space could be curved! Maybe this simple physical view could help us to understand it.
http://www.vacuum...18〈=en


Do your job, mods.
ValeriaT
1 / 5 (1) Apr 08, 2013
..it would deposit so much heat into any mass that it would be vapourised in a fraction of a second..
This is the similar problem, like with explanation of Hubble shift with Coulomb/Thompson scattering. The shielding force just doesn't work so - for example in this experiment the plates are attracted with visible force, but they don't evaporate.
we know the inverse square law is wrong
We know, the relativity doesn't work for rotational curves of stars around galaxies (dark matter) too. And nobody calls for replacement of relativity with something else... The shielding model just explains this violation of relativity with influence of neighboring matter to gravitational shielding.
GSwift7
5 / 5 (1) Apr 08, 2013
We know, the relativity doesn't work for rotational curves of stars around galaxies (dark matter) too. And nobody calls for replacement of relativity with something else...


That is extremely misleading, for anyone who doesn't know the physics.

Different models, based on different forces, lead to different shapes of orbits with different characteristics. It's easy to tell which one applies by observation.

EM force only allows perfectly circular orbits. Anything that strays too close or too far away will be pulled in or go flying off in a short amount of time. This is because EM get weaker with the cube of distance.

Newtonian model of gravity leads to eliptical orbits, but it doesn't explain precession and other observable charactistics.

GR is the only known model that explains the observed galactic motions and characteristics. They are moving exactly as if they are in a gravitational field. We just don't see the source of some of the gravity.
Fleetfoot
5 / 5 (2) Apr 08, 2013
..it would deposit so much heat into any mass that it would be vapourised in a fraction of a second..
This is the similar problem, like with explanation of Hubble shift with Coulomb/Thompson scattering.


Not really, in Thomson scattering, the photon is not absorbed.

The shielding force just doesn't work so - for example in http://www.youtub...nwnEnLCA the plates are attracted with visible force, but they don't evaporate.


Again, the energy of the waves is reflected, not absorbed.

we know the inverse square law is wrong
We know, the relativity doesn't work for rotational curves of stars around galaxies (dark matter) too. And nobody calls for replacement of relativity with something else...


On the contrary, why do you think MOND was invented? That has evolved into STVG and TeVeS, both of which are still being investigated. Fatio's model on the other hand was discarded because it can never work. DM is supported by other tests as well.