APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

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APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by APOD Robot » Thu Jul 11, 2019 4:09 am

[img]https://apod.nasa.gov/apod/calendar/S_190711.jpg[/img] The Ghost of Jupiter's Halo

Explanation: Close-up images of NGC 3242 show the cast off shroud of a dying, sun-like star fancifully known as The Ghost of Jupiter nebula. But this deep and wide telescopic view also finds the seldom seen outer halo of the beautiful planetary nebula at the upper left, toward Milky Way stars and background galaxies in the serpentine constellation Hydra. Intense and otherwise invisible ultraviolet radiation from the nebula's central white dwarf star powers its illusive glow in visible light. In fact, planets of NGC 3242's evolved white dwarf star may have contributed to the nebula's symmetric features and shape. Activity beginning in the star's red giant phase, long before it produced a planetary nebula, is likely the cause of the fainter more extensive halo. About a light-year across NGC 3242 is some 4,500 light-years away. The tenuous clouds of glowing material at the right could well be interstellar gas, by chance close enough to the NGC 3242's white dwarf to be energized by its ultraviolet radiation.

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Ann » Thu Jul 11, 2019 5:22 am

I have two things to say: Teal. And, number two...

This one's for you, starsurfer! :D
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by JohnD » Thu Jul 11, 2019 8:00 am

Are the 'beams' shining around the nebula real, or just artefacts like the diffraction spikes that appear over stars?

Several examples of the latter on that pic, but the beams are differently arranged.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by De58te » Thu Jul 11, 2019 11:13 am

I have two things to say. By Jove that is spooky looking. Second, the Apod said that NGC 3242 is about a light year across and some 4,500 light years away. In the "Close-up" link from 14 years ago Apod said that NGC 3242 is light years across and around 1,400 light years away. This means that in 14 years the nebula has travelled 3,100 light years away from us! But didn't Einstein say that things can't travel faster than the speed of light? At most it should be just 14 light years farther away. Is this proof for warp speed, hyper-space, or the existence of a worm hole?

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Ann » Thu Jul 11, 2019 11:54 am

De58te wrote:
Thu Jul 11, 2019 11:13 am
I have two things to say. By Jove that is spooky looking. Second, the Apod said that NGC 3242 is about a light year across and some 4,500 light years away. In the "Close-up" link from 14 years ago Apod said that NGC 3242 is light years across and around 1,400 light years away. This means that in 14 years the nebula has travelled 3,100 light years away from us! But didn't Einstein say that things can't travel faster than the speed of light? At most it should be just 14 light years farther away. Is this proof for warp speed, hyper-space, or the existence of a worm hole?
I just checked Wikipedia. According to Wikipedia, the Ghost of Jupiter is 1,400 light-years away.

This nebulous ghost hasn't fallen into a wormhole after all, but maybe a "ghost-writer" got things a little mixed up! :D

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by orin stepanek » Thu Jul 11, 2019 11:55 am

Beautiful; but I wish it were enlarged a bit! Guess I'll expand it a bit on paint! :D
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by starsurfer » Thu Jul 11, 2019 12:31 pm

Ann wrote:
Thu Jul 11, 2019 5:22 am
I have two things to say: Teal. And, number two...

This one's for you, starsurfer! :D
Yep it's definitely for me! I get an angelic sense from this?

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by neufer » Thu Jul 11, 2019 12:33 pm

Ann wrote:
Thu Jul 11, 2019 11:54 am
De58te wrote:
Thu Jul 11, 2019 11:13 am

the Apod said that NGC 3242 is about a light year across and some 4,500 light years away. In the "Close-up" link from 14 years ago Apod said that NGC 3242 is light years across and around 1,400 light years away. This means that in 14 years the nebula has travelled 3,100 light years away from us! But didn't Einstein say that things can't travel faster than the speed of light? At most it should be just 14 light years farther away. Is this proof for warp speed, hyper-space, or the existence of a worm hole?
I just checked Wikipedia. According to Wikipedia, the Ghost of Jupiter is 1,400 light-years away.

This nebulous ghost hasn't fallen into a wormhole after all, but maybe a "ghost-writer" got things a little mixed up! :D
Something is sure mixed up :!:

The 1,400 light-years distance has been floating around for a while... but NGC 3242 really is (visually) Jupiter sized (or smaller) with an angular width of ~0.5 arcminutes which makes it only ~0.2 light years across (at 1,400 light-years). NGC 3242 is either noticeably smaller than one light year across or noticeably more distant than 1,400 light-years (or both).
Last edited by neufer on Thu Jul 11, 2019 12:41 pm, edited 1 time in total.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by starsurfer » Thu Jul 11, 2019 12:33 pm

JohnD wrote:
Thu Jul 11, 2019 8:00 am
Are the 'beams' shining around the nebula real, or just artefacts like the diffraction spikes that appear over stars?

Several examples of the latter on that pic, but the beams are differently arranged.
JOhn
These are artifacts caused by the intense brightness of the central shell.

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by NateWhilk » Thu Jul 11, 2019 2:57 pm

Underlining added:
APOD Robot wrote:
Thu Jul 11, 2019 4:09 am
Intense and otherwise invisible ultraviolet radiation from the nebula's central white dwarf star powers its illusive glow in visible light.
"Illusive" is the wrong word here because the glow is real and can be photographed. You may have meant "elusive".

https://www.merriam-webster.com/dictionary/illusive
Definition of illusive
: based on or producing illusion : illusory, deceptive
https://www.merriam-webster.com/dictionary/elusive
Definition of elusive

: tending to elude: such as
a : tending to evade grasp or pursuit elusive prey
b : hard to comprehend or define
c : hard to isolate or identify

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Ann » Thu Jul 11, 2019 3:13 pm

If you follow the rightmost "beam" downwards, you'll come to a very pretty spiral galaxy, sitting square in the middle of the beam. The galaxy is very faint, at 16th magnitude (mag 15.9). My software gives it the designation LEDA 155202. Not much else can be said about it, except that it must be very far away.

Art, if the galaxy has a diameter of, say, 70,000 light-years, and since you have the Ghost of Jupiter to compare it with, can you estimate how big it is in our skies and how far away it must be?

In any case, the galaxy sure is a looker! :D

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Visual_Astronomer » Thu Jul 11, 2019 4:17 pm

starsurfer wrote:
Thu Jul 11, 2019 12:33 pm
JohnD wrote:
Thu Jul 11, 2019 8:00 am
Are the 'beams' shining around the nebula real, or just artefacts like the diffraction spikes that appear over stars?

Several examples of the latter on that pic, but the beams are differently arranged.
JOhn
These are artifacts caused by the intense brightness of the central shell.
This is an amazing picture - I love the wide-angle view.

I think the "beams" JohnD is inquiring about are real - the two coming down below around 5 o'clock and 7 o'clock aren't diffraction spikes. There may be some faint diffraction spikes from the nebula, but they must be aligned the same as the ones on the stars.

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Fred the Cat » Thu Jul 11, 2019 4:24 pm

It is a gorgeous view but before I read the title I thought it was the Cat's Eye Nebula. Did they form similarly :?:

And those astronomical distances are so tough to agree upon. :thumb_up:
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by neufer » Thu Jul 11, 2019 4:27 pm

Ann wrote:
Thu Jul 11, 2019 3:13 pm

Art, if the galaxy has a diameter of, say, 70,000 light-years, and since you have the Ghost of Jupiter to compare it with, can you estimate how big it is in our skies and how far away it must be?
The bright part of NGC 3242 is about 7,000 times as far away as it is wide.

Your galaxy is about 14,000 times as far away as it is wide... or a billion light years.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by dlw » Thu Jul 11, 2019 5:27 pm

Perhaps a naive question: is that yellowish object at the visual center of the Ghost the star that is dying or merely a fortuitous foreground object?
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Case » Thu Jul 11, 2019 5:49 pm

Ann wrote:
Thu Jul 11, 2019 11:54 am
I just checked Wikipedia. According to Wikipedia, the Ghost of Jupiter is 1,400 light-years away.
The source for the Wiki is an older APOD. The cited distance on that APOD was from what appears to be a 1995 (!) article.

Queue 2019 Gaia, for the new distance link (2019), as the parallax is good enough over these kind of distances with this instrument.
From the article:
Parallax: 0.6819 (± 0.0884) mas
Distance: 1.466 (+0.219/−0.168) kpc (≈ 4781 (±13%) light-year).

Image

Assuming a relatively smooth galaxy disk of about 1000 light-year thick, then the nebula would be above the disk.

Image

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by BDanielMayfield » Thu Jul 11, 2019 5:52 pm

dlw wrote:
Thu Jul 11, 2019 5:27 pm
Perhaps a naive question: is that yellowish object at the visual center of the Ghost the star that is dying or merely a fortuitous foreground object?
It is very likely the white dwarf stellar remnant of the star that formed this "planetary" nebula.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Psnarf » Thu Jul 11, 2019 7:21 pm

How are all these distance measurements made? Why the discrepancies?

Hubble sez:
1800 light years https://www.spacetelescope.org/images/opo9738c3/
Image

ESA sez:
Jupiter's Ghost lies some 3000 light-years away
http://www.esa.int/spaceinimages/Images ... er_s_Ghost

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Ann » Thu Jul 11, 2019 8:50 pm

neufer wrote:
Thu Jul 11, 2019 4:27 pm
Ann wrote:
Thu Jul 11, 2019 3:13 pm

Art, if the galaxy has a diameter of, say, 70,000 light-years, and since you have the Ghost of Jupiter to compare it with, can you estimate how big it is in our skies and how far away it must be?
The bright part of NGC 3242 is about 7,000 times as far away as it is wide.

Your galaxy is about 14,000 times as far away as it is wide... or a billion light years.
Thanks, Art! Much appreciated! :D

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by aildoux » Thu Jul 11, 2019 9:24 pm

sort of like the Cat Eye Nebula at center

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Ann » Thu Jul 11, 2019 9:32 pm

dlw wrote:
Thu Jul 11, 2019 5:27 pm
Perhaps a naive question: is that yellowish object at the visual center of the Ghost the star that is dying or merely a fortuitous foreground object?
That's a very good question. The yellowish object is located pretty much exactly where the the dying (or dead) star, the ionizing white dwarf, ought to be. But it actually might be a foreground object! My software, Guide, shows two stars inside the Ghost of Jupiter nebula, one 12th magnitude very blue star that Guide calls TYC 6065 671 1, and one 10th magnitude very red object that Guide calls HD 90255. But Simbad says that HD 90255 is a blue 12th magnitude star! According to SIMBAD, this star is even "visually blue"! But apparently no actual visual-light picture of NGC 3242 shows the central star of NGC 3242 as blue.

(Though maybe it looks a little blue in this image from Caelumobservatory.)

The Ghost of Jupiter in ultraviolet light.
Note the blue (= very ultraviolet) central star. Photo: GALEX.
Wide angle image of the NGC 3243 region.
Photo: Terry Robinson.



















But whether or not the central star of NGC 3242 is blue in visual light, it is most certainly very ultraviolet. In the GALEX image at left, the central star glows brightly blue. In fact, if you look more closely, you will see that it seems to be the entire planetary nebula, not just the central star, that glows blue from far ultraviolet light in GALEX's image.

Note the nebulosity at right in the GALEX image, which is actually the nebulosity at left of NGC 3242 in Terry Robinson's image. Note, too, that in the GALEX image, there is a second blue (=very ultraviolet) star not far from NGC 3242. My software Guide shows me a blue star in more or less the right position which Guide calls TYC 6065 769, but unfortunately SIMBAD doesn't recognize that catalogue number, so I can't find out anything more about that star. But this "TYC 6065 769" is about the same visual magnitude as the (12th magnitude) central star of NGC 3242.

It could be that both the central star of the Ghost of Jupiter, and the hot ultraviolet star not far from it in the sky, are both too faint in visual light to show up as blue stars in any existing optical image of the region around NGC 3242.

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Chris Peterson » Thu Jul 11, 2019 11:04 pm

JohnD wrote:
Thu Jul 11, 2019 8:00 am
Are the 'beams' shining around the nebula real, or just artefacts like the diffraction spikes that appear over stars?
They are real... that is, they are not optical artifacts like diffraction spikes. Whether they are "beams" is a different question (or perhaps the question is "what is a beam?"). What we're seeing could be actual linear concentrations of material, but it could also be preferentially illuminated material, if the stimulating light source is partly occluded (as by dust), resulting in non-uniform illumination of an otherwise fairly homogeneous medium.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by alcor » Thu Jul 11, 2019 11:17 pm

Ann wrote:
Thu Jul 11, 2019 8:50 pm
neufer wrote:
Thu Jul 11, 2019 4:27 pm
Ann wrote:
Thu Jul 11, 2019 3:13 pm

Art, if the galaxy has a diameter of, say, 70,000 light-years, and since you have the Ghost of Jupiter to compare it with, can you estimate how big it is in our skies and how far away it must be?
The bright part of NGC 3242 is about 7,000 times as far away as it is wide.

Your galaxy is about 14,000 times as far away as it is wide... or a billion light years.
Thanks, Art! Much appreciated! :D

Ann
Your estimate of the distance to the far away galaxy, is very good. A request at http://simbad.u-strasbg.fr/simbad/ for this galaxy (LEDA 155215 or PGC 155215) gives an redshift of 14.408 km/s, which gives 200 Mpc (Hubble constant=72km/s/Mpc) or 650 million lightyears. Which is double as distant as the Coma cluster of galaxies.
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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by Boomer12k » Thu Jul 11, 2019 11:42 pm

Looking at it through 3D glasses actually shows a bit of effect on the gaseous nebula to the right...great image

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Re: APOD: The Ghost of Jupiter's Halo (2019 Jul 11)

Post by alter-ego » Fri Jul 12, 2019 5:40 am

alcor wrote:
Thu Jul 11, 2019 11:17 pm
Ann wrote:
Thu Jul 11, 2019 8:50 pm
neufer wrote:
Thu Jul 11, 2019 4:27 pm

The bright part of NGC 3242 is about 7,000 times as far away as it is wide.

Your galaxy is about 14,000 times as far away as it is wide... or a billion light years.
Thanks, Art! Much appreciated! :D

Ann
This estimate of the distance very good. A request at http://simbad.u-strasbg.fr/simbad/ for this galaxy (LEDA 155215 or PGC 155215) gives an redshift of 14.408 km/s, which gives 200 Mpc (Hubble constant=72km/s/Mpc) or 650 million lightyears. Which is double as distant as the Coma cluster of galaxies.
No, Simbad does not say that about NGC 3242.
  • Simbad's data looks to be a direct reference GAIA DR2: Radial velocity - 4.7km/sec and parallax = 0.6819mas ±13% = 4780±650ly. These are the same values as Case's data reference.
  • Even your recession velocity of 14km/s is too low to apply the Hubble constant to estimate a distance. The threshold where cosmological expansion velocities begin to dominate local peculiar velocities is several hundred km/sec. So distances closer than 10's of millions of light years cannot be reliably estimated with a recession velocity.
  • The sub-light-year size estimate is consistent with a young nebula and its expansion rates. Assuming a 30km/s nebula expansion rate (the surrounding ring nebula of SN1987a grows at ~10km/s) places the nova occurring around 10,000 years ago. Note, assuming the primary nebula angular size ~ 0.5 arcmin, GAIA's distance measurement yields a nebula size of 0.7ly
  • Lastly, based on GAIA's distance measurement, the white dwarf (central star) luminosity ≈ 5000 L which is deemed a reasonable value (earlier paper link).
As Case pointed out, many data references are old. All look kosher to me.
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