APOD: The Changing Surface of Fading... (2020 Feb 17)

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APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by APOD Robot » Mon Feb 17, 2020 5:06 am

Image The Changing Surface of Fading Betelgeuse

Explanation: Besides fading, is Betelgeuse changing its appearance? Yes. The famous red supergiant star in the familiar constellation of Orion is so large that telescopes on Earth can actually resolve its surface -- although just barely. The two featured images taken with the European Southern Observatory's Very Large Telescope show how the star's surface appeared during the beginning and end of last year. The earlier image shows Betelgeuse having a much more uniform brightness than the later one, while the lower half of Betelgeuse became significantly dimmer than the top. Now during the first five months of 2019 amateur observations show Betelgeuse actually got slightly brighter, while in the last five months the star dimmed dramatically. Such variability is likely just normal behavior for this famously variable supergiant, but the recent dimming has rekindled discussion on how long it may be before Betelgeuse does go supernova. Since Betelgeuse is about 700 light years away, its eventual supernova -- probably thousands of years in the future -- will likely be an amazing night-sky spectacle, but will not endanger life on Earth.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Sudhamshu » Mon Feb 17, 2020 6:51 am

noob question: How do we deduce the drop in brightness is not because of an object passing in front of Betelgeuse? The second image where the bottom of the star is darkened led me to the question.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Ann » Mon Feb 17, 2020 6:56 am

Sudhamshu wrote:
Mon Feb 17, 2020 6:51 am
noob question: How do we deduce the drop in brightness is not because of an object passing in front of Betelgeuse? The second image where the bottom of the star is darkened led me to the question.
A possible answer is that a huge dust cloud - if so, probably of Betelgeuse's own making - may be located between us and the star, thereby dimming the light of the star.

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Alex_515

Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Alex_515 » Mon Feb 17, 2020 7:42 am

Such fantastic images are obtained by interferometry they say. How does it work and what do we see exactly on the image ? The star's real surface or some kind of computer reconstruction ?

Thanks

Alex

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Simen1 » Mon Feb 17, 2020 10:20 am

Alex: The bluring effect is "optical unsharpness", and not a fuzzy star. We just dont have big enough telescopes to get higher resolution visible light images. Maybe radio telescope interferometry may help. Or just wait for JWST.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Boomer12k » Mon Feb 17, 2020 12:31 pm

A very intriguing star...

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by orin stepanek » Mon Feb 17, 2020 1:47 pm

Long live Betelgeuse! :b:
I really like this star; hope it outlives predictions!
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Geox » Mon Feb 17, 2020 1:57 pm

Look how far we have come in just a few years...

https://apod.nasa.gov/apod/ap090805.html

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by E Fish » Mon Feb 17, 2020 2:25 pm

I want it to go supernova in my lifetime (or rather, I want to have gone supernova hundreds of years ago so I can see it my lifetime). I was too young and in the wrong hemisphere for the supernova in 1987, and I would love to see one myself.

A supernova (in 1572, if I recall correctly) was one of the events that convinced Tycho Brahe that there were no crystalline spheres in the heavens and it made him believe that it was possible for change to occur in a place that had formerly been considered perfect, eternal, and unchanging.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by neufer » Mon Feb 17, 2020 2:40 pm

Alex_515 wrote:
Mon Feb 17, 2020 7:42 am

Such fantastic images are obtained by interferometry they say. How does it work and what do we see exactly on the image ? The star's real surface or some kind of computer reconstruction ?
The four VLT telescopes can indeed be used together as an interferometer for monitoring close double stars down to angular resolutions of ~2 mas (milliarcseconds). However, each 8.2 m VLT telescope has the potential of up to 3.4 times Hubble's 50 mas resolution imaging using adaptive optics. Recent "super Hubble resolution images" all come from SPHERE adaptive optics on ESO’s VLT Unit Telescope 3:
https://en.wikipedia.org/wiki/Spectro-Polarimetric_High-Contrast_Exoplanet_Research wrote:
<<Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). The instrument operates in the visible and near infrared, achieving, albeit over a limited field of view, superior image quality and contrast for bright targets. SPHERE is installed on ESO’s VLT Unit Telescope 3 at the Nasmyth focus. The Infrared Dual-band Imager and Spectrograph (IRDIS) has a field of view of 11" x 12.5" with a pixel scale of 12.25 mas (milliarcsecond). IRDIS can provide classical imaging. Betelgeuse has an angular diameter (i.e., apparent size) ranging from 42 to 56 mas; that range of determinations is ascribed to non-sphericity, limb darkening, pulsations and varying appearance at different wavelengths.>>
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by BDanielMayfield » Mon Feb 17, 2020 2:48 pm

Ann wrote:
Mon Feb 17, 2020 6:56 am
Sudhamshu wrote:
Mon Feb 17, 2020 6:51 am
noob question: How do we deduce the drop in brightness is not because of an object passing in front of Betelgeuse? The second image where the bottom of the star is darkened led me to the question.
A possible answer is that a huge dust cloud - if so, probably of Betelgeuse's own making - may be located between us and the star, thereby dimming the light of the star.

Ann
I was thinking the same thing Ann. Sudhamshu's question is reasonable. Perhaps, the actual surface of Betelgeuse hasn't dimmed at all, but it's just that it has recently burped out a great CME (coronal mass ejection) that is blocking much light as it cools and expands outwards.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Chris Peterson » Mon Feb 17, 2020 2:51 pm

Sudhamshu wrote:
Mon Feb 17, 2020 6:51 am
noob question: How do we deduce the drop in brightness is not because of an object passing in front of Betelgeuse? The second image where the bottom of the star is darkened led me to the question.
As Ann noted, it's possible the dimming is caused by, or related to, dust produced by the star itself, and therefore very local to the star. Dust between us and Betelgeuse, however, sufficiently dense to cause this much apparent dimming, would be readily apparent to instrumental observation. Also, at the angular scale of the star, it would be uniform and would not produce brightness variations across the face of the star.
Chris

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by bystander » Mon Feb 17, 2020 3:21 pm

viewtopic.php?t=40279
Click to view full size image 1 or image 2
The red supergiant star Betelgeuse, in the constellation of Orion, has been undergoing unprecedented dimming. These stunning images of the star’s surface, taken with the SPHERE instrument on ESO’s Very Large Telescope last year, are among the first observations to come out of an observing campaign aimed at understanding why the star is becoming fainter.

SPHERE’s view of Betelgeuse ~ Dec 2019 (1), Jan 2019 (2)
Image Credits: ESO/VLT/SPHERE, M. Montargès et al.
Last edited by bystander on Mon Feb 17, 2020 5:21 pm, edited 1 time in total.
Reason: Added mouseover comparison images from ESO
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by DL MARTIN » Mon Feb 17, 2020 4:00 pm

If the fact that what's being observed happened around 1300 CE, but judged irrelevant; why,then, is 2019 used as a qualifier? One may take liberties with astrophysics nuance, but astronomy loses credibility if context is ignored.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Chris Peterson » Mon Feb 17, 2020 4:17 pm

DL MARTIN wrote:
Mon Feb 17, 2020 4:00 pm
If the fact that what's being observed happened around 1300 CE, but judged irrelevant; why,then, is 2019 used as a qualifier? One may take liberties with astrophysics nuance, but astronomy loses credibility if context is ignored.
Because when it was observed is what's relevant. Not when it happened.

Why is your 40th birthday relevant if you actually "happened" 40 years ago?
Chris

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by neufer » Mon Feb 17, 2020 4:37 pm

APOD Robot wrote:
Mon Feb 17, 2020 5:06 am

Now during the first five months of 2019 amateur observations show Betelgeuse actually got slightly brighter, while in the last five months the star dimmed dramatically. Such variability is likely just normal behavior for this famously variable supergiant, but the recent dimming has rekindled discussion on how long it may be before Betelgeuse does go supernova. Since Betelgeuse is about 700 light years away, its eventual supernova -- probably thousands of years in the future -- will likely be an amazing night-sky spectacle, but will not endanger life on Earth.
DL MARTIN wrote:
Mon Feb 17, 2020 4:00 pm

If the fact that what's being observed happened around 1300 CE, but judged irrelevant; why, then, is 2019 used as a qualifier?
Because the dutifully recorded observations took place in 2019.

Your obsession with some sort of ABSOLUTE TIME FRAME (vis-a-vs the Big Bang)
for anything which took place over the last few million years is really getting to be annoying.

Such matters ARE scientifically irrelevant :!:
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by DL MARTIN » Mon Feb 17, 2020 6:30 pm

Chris Peterson's 'my 40th birthday' reference recognizes that 40 years have elapsed since birth. I'm not the same entity. The way astronomers refer to events as only distance away and not time since, leads one to think that time stands still. Thus, a forty year old person is the same as when that person was born! By denying change, one freeze frames reality.
I agree that we can't know what galaxies, for example, currently look like, but to deny that they are identical to what they looked like is to say that a forty year old adult is still a baby. I'm sorry if I'm annoying about this but I've found instances where there are people who look out the window and believe the world is flat. Surely astronomy doesn't want to be put into that category.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Chris Peterson » Mon Feb 17, 2020 6:41 pm

DL MARTIN wrote:
Mon Feb 17, 2020 6:30 pm
Chris Peterson's 'my 40th birthday' reference recognizes that 40 years have elapsed since birth. I'm not the same entity. The way astronomers refer to events as only distance away and not time since, leads one to think that time stands still. Thus, a forty year old person is the same as when that person was born! By denying change, one freeze frames reality.
I agree that we can't know what galaxies, for example, currently look like, but to deny that they are identical to what they looked like is to say that a forty year old adult is still a baby. I'm sorry if I'm annoying about this but I've found instances where there are people who look out the window and believe the world is flat. Surely astronomy doesn't want to be put into that category.
Your examples totally argue against your own bizarre ideas about astronomical objects!

Bottom line: we care about where something is along its development. We do not care where it is "now" in some other part of the Universe. It is interesting to know what Betelgeuse looked like in 2019 as compared with 2018. It is interesting to know that we are seeing a star that is about 10 million years old. None of this information makes the distance to the star of any interest. Indeed, nothing about the distance of the star from us is relevant to our understanding of the star itself.
Chris

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by neufer » Mon Feb 17, 2020 6:59 pm

DL MARTIN wrote:
Mon Feb 17, 2020 6:30 pm

The way astronomers refer to events as only distance away and not time since, leads one to think that time stands still. Thus, a forty year old person is the same as when that person was born!

By denying change, one freeze frames reality.
:arrow: No one is denying change.

Accurately recording events as they are sequentially observed on the Earth's past light cones provides us our only hope of making any sort of sense of those changes. The best science is that which adopts the simplest approximations that get directly to the heart of understanding.
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by ta152h0 » Mon Feb 17, 2020 10:31 pm

When it goes super nova, I hope cameras are pointing towards where Planet 9 is expected to be and that maybe it would capture any light reflected back to the camera and re find Planet 9 that way. Is it possible to photograph Canis Majoris?
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Chris Peterson » Mon Feb 17, 2020 10:42 pm

ta152h0 wrote:
Mon Feb 17, 2020 10:31 pm
When it goes super nova, I hope cameras are pointing towards where Planet 9 is expected to be and that maybe it would capture any light reflected back to the camera and re find Planet 9 that way. Is it possible to photograph Canis Majoris?
I'd estimate that such a supernova would make Planet 9 about twice as bright as it currently is. Say, about one magnitude brighter. Probably not enough to make much difference when it comes to detection.
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Sudhamshu » Tue Feb 18, 2020 7:07 am

Thanks for your answers, Ann, Bruce, and Chris.

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Ann » Tue Feb 18, 2020 7:35 am

DL MARTIN wrote:
Mon Feb 17, 2020 6:30 pm
Chris Peterson's 'my 40th birthday' reference recognizes that 40 years have elapsed since birth. I'm not the same entity. The way astronomers refer to events as only distance away and not time since, leads one to think that time stands still. Thus, a forty year old person is the same as when that person was born! By denying change, one freeze frames reality.
I agree that we can't know what galaxies, for example, currently look like, but to deny that they are identical to what they looked like is to say that a forty year old adult is still a baby. I'm sorry if I'm annoying about this but I've found instances where there are people who look out the window and believe the world is flat. Surely astronomy doesn't want to be put into that category.
Think of Ötzi the Iceman. He lived near what is now the border between Austria and Italy some 5,000 years ago. He was about 45 years old when he died.

We can't go back in time to see Ötzi when he was alive. We can't see his birth, and we can't see his death. We can't see the landscape where he lived, and we can't see where he found protection. We can't see how Ötzi made a living, and we can't see exactly what happened when he died.

But we do have his dead body, and we can examine it. Surely we shouldn't refrain from examining it, just because there are so many things about Ötzi that we can never know?

In the same way, surely you are not saying that we should refrain from examining the light that reaches us from the stars, just because we can't go back in time and simultaneously travel in space to go to the time and place where the stars were located when they emitted the light that reaches us on the Earth "today"?

Unlike Ötzi, none of the galaxies and few of the stars that we can see in the sky have died since the light that they emitted in the past has reached us. The galaxies have all evolved a little, and the farther away they are, the more they have changed. As for the stars in our own galaxy, most of them are for all intents and purposes completely unchanged, while others may have undergone great changes. We can't see it.

And surely you are not saying that the light that reaches us from stars and galaxies "now" is unimportant, just because that light has taken many years to reach us and there is no way in the Universe that we can ever know what those stars and galaxies are doing "now"? Surely you are not proposing that we should revoke the laws of physics and transport ourselves instantly across the light-years to see what the star or galaxy looks like "now", or else shut up and admit that we know nothing about the Universe?

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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by neufer » Tue Feb 18, 2020 2:27 pm

Ann wrote:
Tue Feb 18, 2020 7:35 am

Think of Ötzi the Iceman. He lived near what is now the border between Austria and Italy some 5,000 years ago. He was about 45 years old when he died.
DO NOT think of Ötzi the Iceman :!:

Our interest in Ötzi has everything to do with the fact that Ötzi lived some 5,000 years ago between Austria and Italy.

Our interest in Betelgeuse has absolutely nothing to do with the absolute time & place where our current observations place Betelgeuse.
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Re: APOD: The Changing Surface of Fading... (2020 Feb 17)

Post by Ann » Tue Feb 18, 2020 2:45 pm

neufer wrote:
Tue Feb 18, 2020 2:27 pm
Ann wrote:
Tue Feb 18, 2020 7:35 am

Think of Ötzi the Iceman. He lived near what is now the border between Austria and Italy some 5,000 years ago. He was about 45 years old when he died.
DO NOT think of Ötzi the Iceman :!:

Our interest in Ötzi has everything to do with the fact that Ötzi lived some 5,000 years ago between Austria and Italy.

Our interest in Betelgeuse has absolutely nothing to do with the absolute time & place where our current observations place Betelgeuse.

Okay, Art. Point taken.

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