APOD: Light Echoes from V838 Mon (2022 Jun 26)

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APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by APOD Robot » Sun Jun 26, 2022 4:05 am

Image Light Echoes from V838 Mon

Explanation: What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon's outer surface suddenly greatly expanded with the result that it became one of the brighter stars in the Milky Way Galaxy in early 2002. Then, just as suddenly, it shrunk and faded. A stellar flash like this had never been seen before -- supernovas and novas expel matter out into space. Although the V838 Mon flash appears to expel material into space, what is seen in the featured image from the Hubble Space Telescope is actually an outwardly expanding light echo of the original flash. In a light echo, light from the flash is reflected by successively more distant surfaces in the complex array of ambient interstellar dust that already surrounded the star. V838 Mon lies about 20,000 light years away toward the constellation of the unicorn (Monoceros), while the light echo above spans about six light years in diameter.

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by VictorBorun » Sun Jun 26, 2022 5:08 am

wikipedia wrote:While the photos appear to depict an expanding spherical shell of debris, they are actually formed by the illumination of an ever-expanding ellipsoid with the progenitor star at one focus and the observer at the other. Hence, despite appearances, the structures in these photos are actually concave toward the viewer.
https://upload.wikimedia.org/wikipedia/ ... 9-2006.gif


I take concave toward the viewer to mean that the furthest (from us) point of the front of the flash is right behind V838 Mon.

I think that radial distance is cT/2 where T is time between the moment we see V838 Mon flash and the moment we take the snapshot.

I think the tangential distance from V838 Mon to the angularly furthest light echo is ≈cT
So it is c(2006 − 2003) = 3 ly for the last frame.

I think the orange to blue scattering halo from the matter in front of V838 Mon must appear slightly before we see 838 Mon flash.

I think angularly large pale violet scattering halo from the matter in front and slightly aside of V838 Mon must appear in the same moment we see V838 Mon flash.
Last edited by bystander on Sun Jun 26, 2022 12:49 pm, edited 1 time in total.
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by De58te » Sun Jun 26, 2022 5:41 am

What I find interesting is that there is some 3 light years of ambient interstellar dust surrounding the star that the light echo reflects off of but then there is no ambient interstellar dust 4 light years out. That's because since this echo began 20 years ago in 2002 shouldn't it have covered another 17 light years? Could the answer be because the dust actually vanishes 3 light years out, or, that since the space increases exponentially so that the dust itself becomes spread out so far that even though there is a reflection it is too dim for our telescopes to capture?

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by VictorBorun » Sun Jun 26, 2022 6:13 am

De58te wrote: Sun Jun 26, 2022 5:41 am What I find interesting is that there is some 3 light years of ambient interstellar dust surrounding the star that the light echo reflects off of but then there is no ambient interstellar dust 4 light years out. That's because since this echo began 20 years ago in 2002 shouldn't it have covered another 17 light years? Could the answer be because the dust actually vanishes 3 light years out, or, that since the space increases exponentially so that the dust itself becomes spread out so far that even though there is a reflection it is too dim for our telescopes to capture?
Suppose the dust reflects just a little portion of the flash and so the flash propogates without losing much of its energy or changing much of its spectrum.

If the dust were in the region all the time and uniformly, then the light echo would dim ~R², where R is the distance from V838 Mon.

If the dust originated from V838 Mon and was flowing all the time with a constant rate, its density would evaporate ~R², so the light echo would dim ~R⁴.

But realistically the dust had originated from V838 Mon and had been being shed just for a month or a year; therefore there must be a shell of dust slowly evaporating
Last edited by VictorBorun on Sun Jun 26, 2022 11:00 am, edited 1 time in total.

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by VictorBorun » Sun Jun 26, 2022 6:37 am

there was a family of ellipsoids drawn at Asterisk in Wed Jun 18, 2014 10:47 am
Image

I think the most narrow one corresponds to red to orange to pale yellow to pale cyan to blue to violet scattering halo in the frame 1
V838 Light Echo_ The Movie 1.jpg
of the posted then video

If fact I can't see the blue here and wonder why
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by orin stepanek » Sun Jun 26, 2022 11:37 am

V838Mon_Hubble_960.jpg
Although it is just a light echo; it is a beautiful light echo in
deed! Makes a nice B-D present for me! :wink: 8-)
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by Ann » Sun Jun 26, 2022 12:37 pm

orin stepanek wrote: Sun Jun 26, 2022 11:37 am V838Mon_Hubble_960.jpg
Although it is just a light echo; it is a beautiful light echo in
deed! Makes a nice B-D present for me! :wink: 8-)
Is it your birthday, Orin? Congrats! 😀 🌺 💐

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by bystander » Sun Jun 26, 2022 12:55 pm

VictorBorun wrote: Sun Jun 26, 2022 5:08 am
wikipedia wrote:While the photos appear to depict an expanding spherical shell of debris, they are actually formed by the illumination of an ever-expanding ellipsoid with the progenitor star at one focus and the observer at the other. Hence, despite appearances, the structures in these photos are actually concave toward the viewer.
APOD Robot wrote: Sun Jun 26, 2022 4:05 am Explanation: ... Although the V838 Mon flash appears to expel material into space, what is seen in the featured image from the Hubble Space Telescope is actually an outwardly expanding light echo of the original flash. In a light echo, light from the flash is reflected by successively more distant surfaces in the complex array of ambient interstellar dust that already surrounded the star. ...
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by orin stepanek » Sun Jun 26, 2022 1:03 pm

Ann wrote: Sun Jun 26, 2022 12:37 pm
orin stepanek wrote: Sun Jun 26, 2022 11:37 am V838Mon_Hubble_960.jpg
Although it is just a light echo; it is a beautiful light echo in
deed! Makes a nice B-D present for me! :wink: 8-)
Is it your birthday, Orin? Congrats! 😀 🌺 💐

Ann
Thanks Ann! Ah yes! Just 82 years young!
Orin

Smile today; tomorrow's another day!

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by AVAO » Sun Jun 26, 2022 1:25 pm

orin stepanek wrote: Sun Jun 26, 2022 1:03 pm
Ann wrote: Sun Jun 26, 2022 12:37 pm
orin stepanek wrote: Sun Jun 26, 2022 11:37 am V838Mon_Hubble_960.jpg
Although it is just a light echo; it is a beautiful light echo in
deed! Makes a nice B-D present for me! :wink: 8-)
Is it your birthday, Orin? Congrats! 😀 🌺 💐

Ann
Thanks Ann! Ah yes! Just 82 years young!
2001: A Space Odyssey
2002: Nova Monocerotis
2004: New Firefox Logo (https://assets.turbologo.com/blog/en/20 ... lution.png)
today: Your birthday, Orin

I like coincidences ;-)

Congratulations 🌺

Image
https://live.staticflickr.com/65535/521 ... 2888_o.jpg
Image
https://live.staticflickr.com/65535/521 ... 2270_o.jpg
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by orin stepanek » Sun Jun 26, 2022 2:13 pm

AVAO wrote: Sun Jun 26, 2022 1:25 pm
orin stepanek wrote: Sun Jun 26, 2022 1:03 pm
Ann wrote: Sun Jun 26, 2022 12:37 pm

Is it your birthday, Orin? Congrats! 😀 🌺 💐

Ann
Thanks Ann! Ah yes! Just 82 years young!
2001: A Space Odyssey
2002: Nova Monocerotis
2004: New Firefox Logo (https://assets.turbologo.com/blog/en/20 ... lution.png)
today: Your birthday, Orin

I like coincidences ;-)

Congratulations 🌺


Thanks!🥳
Orin

Smile today; tomorrow's another day!

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by bystander » Sun Jun 26, 2022 2:59 pm

The image featured here is from Feb 2004. Here are some more images from later in 2004 and from 2005 & 2006. Some earlier images can be seen here.

heic0503a[1].jpg
Oct 2004 ~ NASA, ESA, and Hubble Heritage (AURA/STScI)
heic0617b[1].jpg
Nov 2005 ~ NASA, ESA and H. Bond (STScI)
heic0617c[1].jpg
Sep 2006 ~ NASA, ESA and H. Bond (STScI)
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by Sa Ji Tario » Sun Jun 26, 2022 4:13 pm

Congratulations Orin!!

NCTom

Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by NCTom » Sun Jun 26, 2022 6:38 pm

Orin, I add my congratulations to the others. Hang around for at least another 18!

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by johnnydeep » Sun Jun 26, 2022 8:09 pm

So then, aren't all reflection nebulae essentially "light echo"s?
--
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by Ann » Sun Jun 26, 2022 8:15 pm

johnnydeep wrote: Sun Jun 26, 2022 8:09 pm So then, aren't all reflection nebulae essentially "light echo"s?
Not sure about that. After all, most reflection nebulas don't reflect stellar eruptions. Instead, they reflect a light source that is a lot more constant.

But I do think that the nebula around SN 1987A is (mostly) a light echo. Or am I wrong about that? Chris?


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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by johnnydeep » Sun Jun 26, 2022 8:18 pm

bystander wrote: Sun Jun 26, 2022 12:55 pm
VictorBorun wrote: Sun Jun 26, 2022 5:08 am
wikipedia wrote:While the photos appear to depict an expanding spherical shell of debris, they are actually formed by the illumination of an ever-expanding ellipsoid with the progenitor star at one focus and the observer at the other. Hence, despite appearances, the structures in these photos are actually concave toward the viewer.
APOD Robot wrote: Sun Jun 26, 2022 4:05 am Explanation: ... Although the V838 Mon flash appears to expel material into space, what is seen in the featured image from the Hubble Space Telescope is actually an outwardly expanding light echo of the original flash. In a light echo, light from the flash is reflected by successively more distant surfaces in the complex array of ambient interstellar dust that already surrounded the star. ...
I'm not appreciating what you're pointing out here. Are the two quotes saying the same thing or different things? (And frankly, I don't understand the first one about concave surfaces at all, unless those are simply from the side of the spherical layers of dust surrounding the star farthest from us.)
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by bystander » Sun Jun 26, 2022 8:26 pm

johnnydeep wrote: Sun Jun 26, 2022 8:18 pm
I'm not appreciating what you're pointing out here. Are the two quotes saying the same thing or different things? (And frankly, I don't understand the first one about concave surfaces at all, unless those are simply from the side of the spherical layers of dust surrounding the star farthest from us.)

They are saying the same thing. I was pointing out APOD had already stated what was referenced in wiki.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by johnnydeep » Sun Jun 26, 2022 8:37 pm

bystander wrote: Sun Jun 26, 2022 8:26 pm
johnnydeep wrote: Sun Jun 26, 2022 8:18 pm
I'm not appreciating what you're pointing out here. Are the two quotes saying the same thing or different things? (And frankly, I don't understand the first one about concave surfaces at all, unless those are simply from the side of the spherical layers of dust surrounding the star farthest from us.)

They are saying the same thing. I was pointing out APOD had already stated what was referenced in wiki.
Where are you getting anything about "concavity toward the viewer" from the second quote?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

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Re: APOD: Light Echoes from V838 Mon (2022 Jun 26)

Post by AVAO » Tue Jun 28, 2022 7:11 pm

Ann wrote: Sun Jun 26, 2022 8:15 pm
johnnydeep wrote: Sun Jun 26, 2022 8:09 pm So then, aren't all reflection nebulae essentially "light echo"s?
Not sure about that. After all, most reflection nebulas don't reflect stellar eruptions. Instead, they reflect a light source that is a lot more constant.
But I do think that the nebula around SN 1987A is (mostly) a light echo. Or am I wrong about that? Chris?

Ann
I think the comparison with RS Puppis is also appropriate here.
The light echo also shows the spatial structure of the dust clouds generated by the Cepheid variable star in a "different" light.

Image
Image Credit: NASA/ESA/Hubble Heritage (STScI/AURA)-Hubble/Europe Collab

Images overlay from the Hubble pictures 2002 - 2006:
Image
https://www.flickr.com/photos/185130090 ... ed-public/
https://www.flickr.com/photos/185130090 ... 3/sizes/o/
image processing: jac berne (flickr)