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What's with the weird shape in the bottom left? I don't suppose stars can get squished like that, so it must be some sort of optical artifact?

by kijin 9y ago

jefurii 9y ago
I also thought maybe that was some gravitational lensing effect but TFA says there's a "giant bubble" on the surface so maybe it really is shaped like that.
denis1 9y ago
I guess it is the "vast plume of gas" that the article mentions: The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface.
ajmurmann 9y ago
The article mentions some kind of bubble. Maybe that's it?
chc 9y ago
I could be interpreting the image wrong, but the star appears to be expelling some material on the left. It's not flattened on the bottom so much as bulging in the middle.
pyre 9y ago
From the article: > In this picture, ALMA observes the hot gas of the lower chromosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric. I'm guessing the "explain why it is not symmetric" part is related to this.
privong 9y ago
> What's with the weird shape in the bottom left? I don't suppose stars can get squished like that, so it must be some sort of optical artifact? It's possible that it could be something physical, as some of the other commenters have mentioned. But it also could be a result of the response of the telescope. Interferometers like ALMA do not directly measure the distribution of emission on the sky. Instead they sample the fourier transform of the sky brightness. Because there are discrete pairs of antennas, the full fourier transform cannot be measured. When images such as this are created, the sampling of the fourier plane is deconvolved. But that process does not create a perfect recovery of the sky emission distribution. One would need to look at the raw data, but another explanation for that extension is that it is an artifact of the fourier plane sampling (e.g., analgous to Gibbs Ringing; https://en.wikipedia.org/wiki/Gibbs_phenomenon https://en.wikipedia.org/wiki/Gibbs_phenomenon).
westbywest 9y ago
Despite its immense size, Betelgeuse can be described as a "red hot vacuum." The density of its outer atmosphere / corona is very thin compared to our sun, so it's readily distorted into irregular shapes by the star shedding gas/material.

What's with the weird shape in the bottom left? I don't suppose stars can get squished like that, so it must be some sort of optical artifact?

by kijin 9y ago

What's with the weird shape in the bottom left? I don't suppose stars can get squished like that, so it must be some sort of optical artifact?

jefurii 9y ago

I also thought maybe that was some gravitational lensing effect but TFA says there's a "giant bubble" on the surface so maybe it really is shaped like that.

denis1 9y ago

I guess it is the "vast plume of gas" that the article mentions: The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface.

ajmurmann 9y ago

The article mentions some kind of bubble. Maybe that's it?

chc 9y ago

I could be interpreting the image wrong, but the star appears to be expelling some material on the left. It's not flattened on the bottom so much as bulging in the middle.

pyre 9y ago

From the article: > In this picture, ALMA observes the hot gas of the lower chromosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric. I'm guessing the "explain why it is not symmetric" part is related to this.

privong 9y ago

> What's with the weird shape in the bottom left? I don't suppose stars can get squished like that, so it must be some sort of optical artifact? It's possible that it could be something physical, as some of the other commenters have mentioned. But it also could be a result of the response of the telescope. Interferometers like ALMA do not directly measure the distribution of emission on the sky. Instead they sample the fourier transform of the sky brightness. Because there are discrete pairs of antennas, the full fourier transform cannot be measured. When images such as this are created, the sampling of the fourier plane is deconvolved. But that process does not create a perfect recovery of the sky emission distribution. One would need to look at the raw data, but another explanation for that extension is that it is an artifact of the fourier plane sampling (e.g., analgous to Gibbs Ringing; https://en.wikipedia.org/wiki/Gibbs_phenomenon https://en.wikipedia.org/wiki/Gibbs_phenomenon).

westbywest 9y ago

Despite its immense size, Betelgeuse can be described as a "red hot vacuum." The density of its outer atmosphere / corona is very thin compared to our sun, so it's readily distorted into irregular shapes by the star shedding gas/material.