Last updated July 27, 2017 at 5:12 pm
Catch up on the latest astronomy and astrophysics news with Starstuff every fortnight.
Jupiter’s Great Red Spot in greater detail than ever
The first ever close-up photographs of the Great Red Spot on Jupiter have been captured by the Juno spacecraft. Travelling at 50 kilometres a second, Juno screamed within 9000 kilometres of the planetary oddity, and its cameras captured it in all its glory.
The Great Red Spot is a mammoth hurricane that has been raging for at least 200 years and is so large it would fit two to three Earth’s within it. However it’s always been viewed from afar. The new observations from Juno come as the spacecraft orbits Jupiter passing closer than any spacecraft previously, collecting more detailed information than as ever been possible previously.
The images provide astronomers extraordinary detail of the raging storm. From the dark red core of the storm to small puffy red clouds, the images will allow new insights into the structure, formation and violence of the terrific storm. Researchers hope the images will reveal the answers to other mysteries of the storm, including what causes the red colour, the source of the energy powering the storm, and most interestingly of all – what’s under the cloud tops. Is the storm only occurring at the cloud tops, or does it reach to the surface of the planet?
Since NASA released the raw images on July 12, citizen scientists have been working to process the images in different ways, revealing even more detail and beauty. All the images can be seen on the JunoCam website.
Juno will continue its mission until 2018 or 2019 collecting more information about Jupiter and its spot.
The smallest star
Researchers have discovered the smallest star ever seen, and it’s so tiny it only just even qualifies as a star.
EBLM J0555–57Ab, located around 600 light-years away from Earth, is only just larger than Saturn – which by star standards is miniscule. Had it had any less mass it would have been too small to maintain fusion of hydrogen into helium at its core, becoming a brown dwarf.
The star is incredibly dim – our own sun is around 2000-3000 times brighter – however it basks in the glow of a larger star it itself orbits. As yet it’s unknown if there are any planets associated with the star.It’s thought that stars smaller than our sun might be extremely common in the universe, however their small size makes them difficult to detect and observe. EBLM J0555–57Ab, though, appears to take that diminutive size to an extreme.
Loved up planet-like objects
It’s not every day that there is a romantic element to astronomy, but researchers at the WM Keck observatory in Hawaii may have found two planet-like objects which invoke just that.
In 2016 researchers observed a low-gravity brown dwarf named 2MASS J11193254—1137466. But revisiting these objects in March they discovered it wasn’t one object, but two.
In mass they’re around 4 times the size of Jupiter placing them in a grey area between planets and stars, but most interestingly – they’re not orbiting a star. Instead the two objects wander the universe locked in each other’s embrace, belonging to nothing but each other.
You can read an analysis of the binary system at the American Astronomical Society.
Our Sun isn’t so unique afterall
There has been an ongoing argument about whether our Sun is unique or just an ordinary star. While it might look like some other stars in our galaxy, its solar cycles appeared to behave in a different way to what we observed elsewhere. But now a new paper has suggested that it’s not unique afterall.
Over a period of 11 years our Sun transitions through magnetic activity levels, from peaks of high magnetic activity-caused sunspots to periods of little. To try to understand this cycle better, researchers simulated the internal dynamo of the sun. In the sun’s interior is a turbulent region called the convection zone, where streams of solar plasma create electrical currents. These currents cause a magnetic field to form.
By simulating this dynamo and magnetic fields of other stars, the researchers found that the magnetic cycle is controlled by the relationship between its inertial force and the Coriolis force. This relationship, called the Rossby number, is inversely proportional to the star’s cycle period – so when the Rossby number is high the solar cycle period is short, and a high Rossby number results in a short solar cycle. This relationship held across the stars simulated, including our sun.
Even though our sun’s cycle may be very different to other stars we can observe, it turns out it’s behaviour isn’t as unique as we thought it may be.
Jupiter image courtesy of NASA/JPL-Caltech/MSSS/SwRI/Kevin M Gill
Star size comparison courtesy of Alexander von Boetticher et al
Artist impression of binary planets courtesy of Gemini Observatory/Jon Lomberg Illustration