Tag: Very Large Telescope

VLT takes picture of exoplanet

9:20 am

VLT's picture of exoplanet
Click for original image.

The ground-based Very Large Telescope (VLT) in Chile has successfully taken a picture of an exoplanet four to six times larger than Jupiter that is circling its star at about the same distance as Saturn.

That picture, cropped to post here, is to the right. Other data from other observatories had suggested the star AF Leporis, 87.5 light years away, might have an exoplanet, so astronomers decided to focus VLT on it to see if it could spot it.

AF Leporis is about as massive and as hot as the sun, ESO wrote in the statement, and in addition to its one known planet the star also has a disk of debris similar to the solar system’s Kuiper Belt. AF Leporis is, however, much younger than the sun. At 24 million years old, it is about 200 times younger than our star. This young age makes AF Leporis and its planetary system especially intriguing for astronomers as it can provide important insights into the evolution of our own solar system.

To snap this picture, the VLT had to use adaptive optics to smooth out the fuzziness produced by the Earth’s atmosphere, while also blocking out the star’s own light (as shown by the black disk in the image).

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Neptune’s cooling when it should be warming

9:45 am

Neptune since 2006

The uncertainty of science: Observations of Neptune during the past seventeen years using the Very Large Telescope have shown the planet mostly cooling during this time period, even though Neptune was moving into its summer season.

Astronomers looked at nearly 100 thermal-infrared images of Neptune, captured over a 17-year period, to piece together overall trends in the planet’s temperature in greater detail than ever before. These data showed that, despite the onset of southern summer, most of the planet had gradually cooled over the last two decades. The globally averaged temperature of Neptune dropped by 8 °C between 2003 and 2018.

The astronomers were then surprised to discover a dramatic warming of Neptune’s south pole during the last two years of their observations, when temperatures rapidly rose 11 °C between 2018 and 2020. Although Neptune’s warm polar vortex has been known for many years, such rapid polar warming has never been previously observed on the planet. “Our data cover less than half of a Neptune season, so no one was expecting to see large and rapid changes,” says co-author Glenn Orton, senior research scientist at Caltech’s Jet Propulsion Laboratory (JPL) in the US.

The sequence of photos above show that change over time. Lower latitudes generally get darker, or cooler, while the south pole suddenly brightens, getting hotter, in 2020.

The scientists have no idea why this has happened, though they have theories, ranging from simple random weather patterns to the influence of the Sun’s sunspot cycle.

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Betelgeuse is closer and smaller than previously thought

12:12 pm

Betelgeuse's fading
Images taken by Europe’s
Very Large Telescope in Chile

The uncertainty of science: A new analysis by scientists of Betelgeuse, triggered by its dip in brightness in 2020, has concluded that the red giant star is both closer and smaller than previously estimated.

Their analysis reported a present-day mass of 16.5 to 19 solar mass—which is slightly lower than the most recent estimates. The study also revealed how big Betelgeuse is, as well as its distance from Earth. The star’s actual size has been a bit of a mystery: earlier studies, for instance, suggested it could be bigger than the orbit of Jupiter. However, the team’s results showed Betelgeuse only extends out to two-thirds of that, with a radius 750 times the radius of the sun. Once the physical size of the star is known, it will be possible to determine its distance from Earth. Thus far, the team’s results show it is a mere 530 light years from us, or 25 percent closer than previously thought.

The research also suggested that the star is in the initial stages of burning helium rather than hydrogen, and so it likely more than 100,000 years from going supernova.

As for the dimming, the scientists concluded (as other have) that the dimming in ’20 was due to the passage of a dust cloud in front of the star.

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