Feeds

Hubble spies North Star's little brother

Actually a triple-star system

Choosing a cloud hosting partner with confidence

The Hubble Space telescope has finally snapped a third member of the Polaris star group previously known only by its gravitational pull on its companion, thereby visibly demonstrating that the "North Star" is indeed a trio of stars.

The group, made up of Polaris A, B and (new family member) Ab lies around 430 light years from Earth, more-or-less at our celestial north pole, as the left-hand frame here shows:

Polaris A, B and Ab

Top right is Polaris A, and distant companion Polaris B - the latter first spotted by William Herschel in 1780. The two are separated by 240bn miles, and Polaris B can been seen through small telescopes.

Not so Polaris Ab (bottom right), which is just two billion miles from Polaris A. As Smithsonian astronomer Nancy Evans put it: "The star we observed is so close to Polaris that we needed every available bit of Hubble's resolution to see it."

Howard Bond of the Space Telescope Science Institute further explained that while Polaris is a "supergiant more than two thousand times brighter than the Sun", Polaris Ab is a main sequence star. Accordingly, the brightness difference between the two "made it even more difficult to resolve them". Bond noted: "With Hubble, we've pulled the North Star's companion out of the shadows and into the spotlight."

Rather nicely, the blurb illustrates it thus: "The companion proved to be less than two-tenths of an arcsecond from Polaris — an incredibly tiny angle equivalent to the apparent diameter of a quarter located 19 miles away."

The practical applications of the discovery relate to ultimately calculating the mass of Polaris A, considered vital because it is the nearest "Cepheid variable star" the brightness variations of which are used to "measure the distances of galaxies and the expansion rate of the universe".

Evans concluded: "Our ultimate goal is the get an accurate mass for Polaris. To do that, the next milestone is to measure the motion of the companion in its orbit." ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
GRAV WAVE DRAMA: 'Big Bang echo' may have been grit on the scanner – boffins
Exit Planet Dust on faster-than-light expansion of universe
Mine Bitcoins with PENCIL and PAPER
Forget Sudoku, crunch SHA-256 algos
SpaceX Dragon cargo truck flies 3D printer to ISS: Clawdown in 3, 2...
Craft berths at space station with supplies, experiments, toys
'This BITE MARK is a SMOKING GUN': Boffins probe ancient assault
Tooth embedded in thigh bone may tell who pulled the trigger
DOLPHINS SMELL MAGNETS – did we hear that right, boffins?
Xavier's School for Gifted Magnetotaceans
Big dinosaur wowed females with its ENORMOUS HOOTER
That's right, Doris, I've got biggest snout in the prehistoric world
Japanese volcano eruption reportedly leaves 31 people presumed dead
Hopes fade of finding survivors on Mount Ontake
That glass of water you just drank? It was OLDER than the SUN
One MEELLION years older. Some of it anyway
Canberra drone team dances a samba in Outback Challenge
CSIRO's 'missing bushwalker' found and watered
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.