Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



STELLAR CHEMISTRY
How Far Away Are Our Stellar Neighbors?
by Staff Writers
Washington DC (SPX) May 20, 2016


All stars in our Milky Way galaxy are moving. Most stars circle around the galactic center in various orbits. As seen from our perspective on Earth we therefore see small "proper motions" of other stars. In the past general all-sky surveys were utilized to identify stars which appear to have relatively fast proper motions, thus suspected to be nearby.

In April 2016 the United States Naval Observatory (USNO) released a catalog of distances to over 112 thousand stars, the USNO Parallax Catalog (UPC), using ground-based observations performed with the USNO Robotic Astrometric Telescope (URAT). It is the largest such catalog since the release of the European Space Agency (ESA) Hipparcos mission Catalog in 1997.

The brightest stars in the night sky are not always the nearest in space because the intrinsic brightness of stars varies over a huge range. Some stars are only 1/1000 as bright as our Sun, others thousands of times brighter. Many of the bright stars we can see with the naked eye are far away, luminous, giant stars. So how do we know the distance to the stars?

If you hold a finger in front of your face and alternately watch it with one eye, then the other, your finger appears to be shifting in front of the more distant background. The exact same thing happens when observing a nearby star as the Earth moves around our Sun: a nearby star seems to move slightly with respect to most other stars in the same field of view which are further away.

The small angle the star appears to move is called the parallactic angle, and after performing reductions of such observations astronomers end up with a trigonometric parallax, which is the most direct measurement of a star's distance based on geometry and the known size of Earth's orbit around the Sun, without the need of any other assumptions or physical models. A star with a parallax of one arcsecond would be located at a distance of one parsec (pc) or 3.26 light-years from the solar system.

All stars in our Milky Way galaxy are moving. Most stars circle around the galactic center in various orbits. As seen from our perspective on Earth we therefore see small "proper motions" of other stars. In the past general all-sky surveys were utilized to identify stars which appear to have relatively fast proper motions, thus suspected to be nearby.

These stars were then targeted one-by-one to find parallactic motion in order to derive a distance. Such centuries-long work culminated with the 1995 release of the Yale General Catalogue of Trigonometric Parallaxes, listing the distances to almost 16 thousand stars.

The ESA Hipparcos Catalogue contains almost 120 thousand stars with very precise positions, proper motions and parallaxes measured by a dedicated satellite mission. It is complete over the entire sky, but it is limited to relatively bright stars and many entries do not reveal a significant parallax, just giving a "this star is too far away to be measured" result.

The new UPC is based on 3 years of observing at the Naval Observatory Flagstaff Station (NOFS) in Arizona using the wide-field URAT astrograph. It has a much fainter magnitude limit than Hipparcos, observing stars as faint at magnitude 17, and covers over 1/2 of the sky north of -13 degrees declination. No pre-selection of candidates based on proper motions were made.

A total of over 200 million stars were observed, most of them too far away for a reliable parallax result. USNO astronomers Charlie Finch and Norbert Zacharias found trigonometric parallaxes for over 58 thousand previously known nearby stars and made the first trigonometric parallax measures of 53,500 newly discovered nearby stars with an average precision of about 4 milli-arcseconds.

This angle corresponds to just over 1/1000 of an inch as seen from a mile away. The closest star discovery in UPC is about 25 light years away, which astronomers call "nearby" although this is still over 1.5 million times the distance between Earth and Sun.

The UPC is published by the Centre de Donnees Astronomiques (CDS) in Strasbourg, France and its mirror sites around the world as catalog I/333.

Even more stellar distance measures are expected soon from the PanSTARRS project which uses a much larger telescope than the USNO astrograph, and by about 2018 the first parallax results are expected from the European Gaia space mission.

Research paper: "Parallax Results From URAT Epoch Data"


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

.


Related Links
United States Naval Observatory
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

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

Previous Report
STELLAR CHEMISTRY
Silicate stardust traces histories of dust in the galaxy
Houston TX (SPX) May 10, 2016
NASA scientists are revealing the histories of dust particles from dying stars that roved the Galaxy for millions of years before the sun and planets formed. These stardust grains survived the harsh environment of deep space and were found in meteorites on Earth. During their journeys, these stardust grains were bombarded in space by high-energy cosmic radiation and shock waves from explod ... read more


STELLAR CHEMISTRY
NASA research gives new insights into how the Moon got inked

First rocket made ready for launch at Vostochny spaceport

Supernova iron found on the moon

Russia to shift all Lunar launches to Vostochny Cosmodrome

STELLAR CHEMISTRY
AAC Microtec to develop miniaturized motion controller for space rovers and robots

Mars Rover Scientist Hopes to Find More Evidence of Liquid Water on the Red Planet

The rise and fall of Martian lakes

Opportunity microscopic imaging camera back to normal operations

STELLAR CHEMISTRY
Interns Make Archived NASA Planetary Science Data More Accessible

Out of this world: 'Moon and Mars veggies' grow in Dutch greenhouse

NASA Invests in Next Stage of Visionary Technology Development

NASA makes dozens of patents available in public domain

STELLAR CHEMISTRY
China, U.S. hold first dialogue on outer space safety

Long March-7 rocket delivered to launch site

China's space technology extraordinary, impressive says Euro Space Center director

China can meet Chile's satellite needs: ambassador

STELLAR CHEMISTRY
ISS completes 100,000th orbit of Earth: mission control

Canadian astronaut to join ISS in 2018

NASA, Space Station partners announce future mission crew members

New landing date for ESA astronaut Tim Peake

STELLAR CHEMISTRY
Russia Spent $1.3Bln on Vostochny Cosmodrome So Far

Pre-launch processing is underway with Indonesia's BRIsat for the next Arianespace heavy-lift flight

New Antares Rocket Rolls Out at NASA Wallops

First work platforms powered tested in VAB for Space Launch System

STELLAR CHEMISTRY
Star Has Four Mini-Neptunes Orbiting in Lock Step

Exoplanets' Orbits Point to Planetary Migration

Synchronized planets reveal clues to planet formation

Kepler space telescope finds another 1284 exo planets

STELLAR CHEMISTRY
Lockheed, Indra conduct test of new radar system

Scientists take a major leap toward a 'perfect' quantum metamaterial

UW team first to measure microscale granular crystal dynamics

Self-healing, flexible electronic material restores functions after many breaks




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