Subscribe free to our newsletters via your
. 24/7 Space News .




Subscribe free to our newsletters via your




















PHYSICS NEWS
Hubble Astronomers Measure White Dwarf's Mass with Relativity Experiment
by Staff Writers
Baltimore MD (SPX) Jun 08, 2017


Albert Einstein reshaped our understanding of the fabric of space. In his general theory of relativity in 1915, he proposed the revolutionary idea that massive objects warp space, due to the effects of gravity. Until that time, Isaac Newton's theory of gravity from two centuries earlier held sway: that space was unchanging. Einstein's theory was experimentally verified four years later when a team led by British astronomer Sir Arthur Eddington measured how much the sun's gravity deflected the image of a background star as its light grazed the sun during a solar eclipse.

Astronomers have used the sharp vision of NASA's Hubble Space Telescope to repeat a century-old test of Einstein's general theory of relativity. The Hubble team measured the mass of a white dwarf, the burned-out remnant of a normal star, by seeing how much it deflects the light from a background star.

This observation represents the first time Hubble has witnessed this type of effect created by a star. The data provide a solid estimate of the white dwarf's mass and yield insights into theories of the structure and composition of the burned-out star.

First proposed in 1915, Einstein's general relativity theory describes how massive objects warp space, which we feel as gravity. The theory was experimentally verified four years later when a team led by British astronomer Sir Arthur Eddington measured how much the Sun's gravity deflected the image of a background star as its light grazed the Sun during a solar eclipse, an effect called gravitational microlensing.

Astronomers can use this effect to see magnified images of distant galaxies or, at closer range, to measure tiny shifts in a star's apparent position on the sky. Researchers had to wait a century, however, to build telescopes powerful enough to detect this gravitational warping phenomenon caused by a star outside our solar system. The amount of deflection is so small only the sharpness of Hubble could measure it.

Hubble observed the nearby white dwarf star Stein 2051B as it passed in front of a background star. During the close alignment, the white dwarf's gravity bent the light from the distant star, making it appear offset by about 2 milliarcseconds from its actual position. This deviation is so small that it is equivalent to observing an ant crawl across the surface of a quarter from 1,500 miles away.

Using the deflection measurement, the Hubble astronomers calculated that the white dwarf's mass is roughly 68 percent of the Sun's mass. This result matches theoretical predictions.

The technique opens a window on a new method to determine a star's mass. Normally, if a star has a companion, astronomers can determine its mass by measuring the double-star system's orbital motion. Although Stein 2051B has a companion, a bright red dwarf, astronomers cannot accurately measure its mass because the stars are too far apart. The stars are at least 5 billion miles apart - almost twice Pluto's present distance from the Sun.

"This microlensing method is a very independent and direct way to determine the mass of a star," explained lead researcher Kailash Sahu of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. "It's like placing the star on a scale: the deflection is analogous to the movement of the needle on the scale."

The Hubble analysis also helped the astronomers to independently verify the theory of how a white dwarf's radius is determined by its mass, an idea first proposed in 1935 by Indian American astronomer Subrahmanyan Chandrasekhar. "Our measurement is a nice confirmation of white dwarf theory, and it even tells us the internal composition of a white dwarf," said team member Howard Bond of Pennsylvania State University in University Park.

Sahu's team identified Stein 2051B and its background star after combing through data of more than 5,000 stars in a catalog of nearby stars that appear to move quickly across the sky. Stars with a higher apparent motion across the sky have a greater chance of passing in front of a distant background star, where the deflection of light can be measured.

After identifying Stein 2051B and mapping the background star field, the researchers used Hubble's Wide Field Camera 3 to observe the white dwarf seven different times over a two-year period as it moved past the selected background star.

The Hubble observations were challenging and time-consuming. The research team had to analyze the white dwarf's velocity and the direction it was moving in order to predict when it would arrive at a position to bend the starlight so the astronomers could observe the phenomenon with Hubble.

The astronomers also had to measure the tiny amount of deflected starlight. "Stein 2051B appears 400 times brighter than the distant background star," said team member Jay Anderson of STScI, who led the analysis to precisely measure the positions of stars in the Hubble images. "So measuring the extremely small deflection is like trying to see a firefly move next to a light bulb. The movement of the insect is very small, and the glow of the light bulb makes it difficult to see the insect moving." In fact, the slight movement is about 1,000 times smaller than the measurement made by Eddington in his 1919 experiment.

Stein 2051B is named for its discoverer, Dutch Roman Catholic priest and astronomer Johan Stein. It resides 17 light-years from Earth and is estimated to be about 2.7 billion years old. The background star is about 5,000 light-years away.

The researchers plan to use Hubble to conduct a similar microlensing study with Proxima Centauri, our solar system's closest stellar neighbor.

Sahu presented his team's findings at June 7, at the American Astronomical Society meeting in Austin, Texas.

PHYSICS NEWS
Are dense star clusters the origin of the gravitational waves discovered by LIGO?
San Francisco CA (SPX) Jun 05, 2017
Astrophysicists everywhere are thrilled about yesterday's news that the LIGO experiment has detected its third set of gravitational waves. Predicted more than a century ago by Albert Einstein, and finally detected by LIGO for the first time in 2015, gravitational waves have opened an entirely new way of observing the universe's most violent events. The origin of each of the trio of gravita ... read more

Related Links
Space Telescope Science Institute
The Physics of Time and Space

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

PHYSICS NEWS
Roscosmos Says Cooperation With NASA Unaffected by 'Political Outbursts'

Russia's New 'Federation' Spacecraft to be Launched from Baikonur in 2022

Astronauts return after marathon ISS mission

From 2D to 3D, Space Station Microscope Gets an Upgrade

PHYSICS NEWS
SpaceX's first recycled Dragon arrives at space station

SpaceX blasts off cargo using recycled spaceship

India shows off space prowess with launch of mega-rocket

Eutelsat signs new launch contract with Arianespace

PHYSICS NEWS
Study estimates amount of water needed to carve Martian valleys

Collateral damage from cosmic rays increases cancer risks for Mars astronauts

Curiosity Peels Back Layers on Ancient Martian Lake

Student-Made Mars Rover Concepts Lift Off

PHYSICS NEWS
Spotlight: First China-designed experiment flies to space station

News Analysis: U.S.-China space freeze may thaw with new commercial pathway

China willing to cooperate in peaceful space exploration: Xi

California Woman Charged for Trying to Hand Over Sensitive Space Tech to China

PHYSICS NEWS
Thomas Pesquet returns to Earth

Propose a course idea for the CU space minor

Leading Global Air And Space Law Group Joins Reed Smith

New Horizons for Alexander Gerst

PHYSICS NEWS
Study proves viability of quantum satellite communications

Indian Space Agency to Work on Electric Propulsion for Large Satellites

Saudi deal for counterfire radars approved by U.S. State Department

Mitsubishi Electric Completes New Satellite Component Production Facility

PHYSICS NEWS
Discovery reveals planet almost as hot as the Sun

A planet hotter than most stars

Hubble's tale of 2 exoplanets - Nature vs nurture

Astronomers discover alien world hotter than most stars

PHYSICS NEWS
A whole new Jupiter with first science results from Juno

First results from Juno show cyclones and massive magnetism

Jupiters complex transient auroras

NASA's Juno probe forces 'rethink' on Jupiter




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement