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posted by martyb on Tuesday January 29 2019, @10:59PM   Printer-friendly
from the occultation-is-like-a-Ouija-board,-right? dept.

Astronomers Have Detected a Curious Object at The Edge of Our Solar System

For over 70 years, scientists have been predicting the existence of a certain kind of object in the outer Solar System. Small in size, these potential bodies are thought to constitute an important early step in the planet formation process.

Since these hypothetical objects are only between 1 and 10 kilometres in radius (0.6 to 6.2 miles), it's tricky to spot them from where we sit. But now astronomers think they have done it. By staring at the sky for hours, they've obtained evidence of an object just 1.3 kilometres (0.8 miles) in radius, in the vicinity of Pluto's orbit. The find could finally be a representative of this proposed class of small, 'kilometre-sized' Kuiper Belt objects.

Given their small size and dimness, the objects can't be seen directly. So astronomers from the National Astronomical Observatory of Japan tried another method - occultation. This means essentially lying in wait and staring at a star, waiting for an object to pass in front of it and block some of its light. They picked out 2,000 stars, and spent a total of 60 hours observing them with the help of two small, 28-centimetre (11-inch) telescopes. The work paid off - the team found evidence of a tiny body called a planetesimal orbiting the Sun at a distance of 32 astronomical units (AU). This actually places it within Pluto's orbital range, which is between 29 and 49 AU.

[...] And the team isn't done yet. They have their sights on a much more distant prize. "Now that we know our system works, we will investigate the Edgeworth-Kuiper Belt in more detail," [NAOJ astronomer Ko] Arimatsu said. "We also have our sights set on the still undiscovered Oort Cloud out beyond that."

Also at Space.com.

A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes (DOI: 10.1038/s41550-018-0685-8) (DX)


Original Submission

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A 4.7 km Asteroid May Briefly Occult the Brightest Star in the Night Sky 7 comments

A 5km asteroid may briefly occult the brightest star in the night sky

On Monday night, for a few areas of South and Central America, as well as the Caribbean, Sirius will probably briefly disappear. This will occur as a small asteroid passes in front of the star, occulting it for up to 1.6 seconds, according to the International Occultation Timing Association. (Yes, the acronym is IOTA).

In this case, the asteroid 4388 Jürgenstock will have an apparent diameter just an iota bigger than Sirius. The angular diameter of the asteroid is about 0.007 arcseconds (an arcsecond is 1/3,600th of a degree of the night sky), whereas the angular diameter of Sirius is 0.006 arcseconds. Thus, as the asteroid passes in front of Sirius, the star will briefly dim, perhaps completely, before quickly brightening again. Sirius may appear to blink once, slowly.

[...] With a diameter of 4.7km, this inner-asteroid belt object was discovered in 1964 by an astronomer named—you guessed it—Jürgen Stock. This occultation should allow astronomers a rare opportunity to better characterize the dimensions of the asteroid. It is likely to have an irregular shape—further contributing to the uncertainty about the extent to which it will block the light from Sirius.

4388 Jürgenstock.

Related: Ring Confirmed Around Dwarf Planet Haumea
One Last Stellar Occultation of 2014 MU69 to be Observed Before Jan. 1 New Horizons Flyby
Distant Kuiper Belt Planetesimal Found Using Occultation


Original Submission

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  • (Score: -1, Troll) by Anonymous Coward on Tuesday January 29 2019, @11:20PM

    by Anonymous Coward on Tuesday January 29 2019, @11:20PM (#793822)

    Stare at the wall long enough and you'll see things. Doesn't mean they're there. And now these bozos announce that they're going to stare twice as long to see even more stuff. Remember, kids: don't mix drugs and astrophysics.

  • (Score: 2) by CZB on Wednesday January 30 2019, @03:56AM

    by CZB (6457) on Wednesday January 30 2019, @03:56AM (#793898)

    Japanese Scientist Finds New Planet Using the Occult!

    Researchers expect to find many more in next ritual. Elon Musk has not yet commented on the possibility of when he can send a rocket to visit this exciting new planet. Will the Trump administration demand naming rights?

  • (Score: 2) by iWantToKeepAnon on Thursday January 31 2019, @05:01PM

    by iWantToKeepAnon (686) Subscriber Badge on Thursday January 31 2019, @05:01PM (#794583) Homepage Journal
    When a star dims they say it is from an exoplanet. How can they tell a KBO from an exoplanet? Does the KBO cause a huge dip in brightness when an exo causes a small dip? Perhaps the speed of the occultation? These are pretty small telescopes so it is unlikely they are very precise and unlikely to detect exo occultation. Hmmmm.
    --
    "Happy families are all alike; every unhappy family is unhappy in its own way." -- Anna Karenina by Leo Tolstoy
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