APOD: NGC 7293: The Helix Nebula (2024 Oct 24)

[APOD Robot]

NGC 7293: The Helix Nebula

Explanation: A mere seven hundred light years from Earth toward the constellation Aquarius, a star is dying. The once sun-like star's last few thousand years have produced the Helix Nebula. Also known as NGC 7293, the cosmic Helix is a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. Combining narrow band data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, this deep image shows tantalizing details of the Helix, including its bright inner region about 3 light-years across. The white dot at the Helix's center is this Planetary Nebula's hot, dying central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.

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[Ann]

Nice APOD. And a very big picture, too, 1.05 MB.

NGC 7293: The Helix Nebula. Image Credit & Copyright: Patrick Winkler

I don't usually have that much to say about planetary nebulas, but this closeup is my favorite picture of the Helix Nebula:

Comet-like filaments along the inner rim of the Helix Nebula. Credit: C. Robert O'Dell and Kerry P. Handron and NASA

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We have been talking about pillars lately, like the Pillars of Creation in the Eagle Nebula. Well, the filaments along the inner rim of the Helix Nebula are a kind of pillars of their own! And just like other pillars, they have been sculpted by the harsh ultraviolet light and strong stellar wind of a hot star. The difference is that the Pillars of Creation have been sculpted by big, massive O-type stars which shine due to furious fusion processes, whereas the cometary filaments of the Helix Nebula have been sculpted by a tiny planetary nebula central star, which shines because it is rapidly shrinking and exposing its extremely hot innards.

The typical size of an O-type star, compared with the sizes of other main sequence stars. Credit: Rursus.

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Size comparison between A-type main sequence star (Sirius) and its white dwarf. Credit: NASA, ESA and G. Bacon (STScI)

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And the tiny but incredibly hot central star of a planetary nebula is making its cast-off outer layers glow and fluoresce in the process, and creating those cometary fingers pointing at the central star.

Oh, and... just because I was speaking of Sirius (and its white dwarf), I can't keep this from you. Why is Sirius some 22 times brighter than the Sun in visible light, even though it's not that much bigger? It's because its surface brightness is so much higher than the Sun's. Just look at this picture:

Comparison of Sirius A and the Sun, to scale and relative surface brightness. Credit: Tomruen.

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Wowzers!

Ann

[AVAO]

Nice APOD. And a very big picture, too, 1.05 MB.

[...]

I don't usually have that much to say about planetary nebulas, but this closeup is my favorite picture of the Helix Nebula:

Comet-like filaments along the inner rim of the Helix Nebula. Credit: C. Robert O'Dell and Kerry P. Handron and NASA

---

We have been talking about pillars lately, like the Pillars of Creation in the Eagle Nebula. Well, the filaments along the inner rim of the Helix Nebula are a kind of pillars of their own! And just like other pillars, they have been sculpted by the harsh ultraviolet light and strong stellar wind of a hot star. The difference is that the Pillars of Creation have been sculpted by big, massive O-type stars which shine due to furious fusion processes, whereas the cometary filaments of the Helix Nebula have been sculpted by a tiny planetary nebula central star, which shines because it is rapidly shrinking and exposing its extremely hot innards.

[...]

Ann

ThanX Ann

Unfortunately, I cannot say whether your comet-like filaments along the inner rim of the Helix Nebula are also EGGs in the scientific sense. Apparently the JWST is currently investigating this, as the corresponding JWST images of the inner ring of the Helix Nebula have not yet been released. A small section further out is already public. Unfortunately, you can't see very much there.

Jac

Click to view full size image

artistic composit with JWST placement

Click to view full size image

Original Data: NASA/ESA/CSA (JWST)

[Locutus76]

Comet-like filaments along the inner rim of the Helix Nebula. Credit: C. Robert O'Dell and Kerry P. Handron and NASA

---

We have been talking about pillars lately, like the Pillars of Creation in the Eagle Nebula. Well, the filaments along the inner rim of the Helix Nebula are a kind of pillars of their own! And just like other pillars, they have been sculpted by the harsh ultraviolet light and strong stellar wind of a hot star. The difference is that the Pillars of Creation have been sculpted by big, massive O-type stars which shine due to furious fusion processes, whereas the cometary filaments of the Helix Nebula have been sculpted by a tiny planetary nebula central star, which shines because it is rapidly shrinking and exposing its extremely hot innards.

Nice closeup! These cometary filaments remind me a bit of the Bullet Time vfx from The Matrix Now where’s my red pill…

[Christian G.]

I don't usually have that much to say about planetary nebulas, but this closeup is my favorite picture of the Helix Nebula:

Comet-like filaments along the inner rim of the Helix Nebula. Credit: C. Robert O'Dell and Kerry P. Handron and NASA

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Ann

I also like those tiny cometary knots all around the central star, supposedly there are some 40 000 of them in the Helix Nebula and the head alone of each one is the size of the solar system, so nothing tiny here!
Those of the smaller Eskimo Nebula are less numerous but more obvious without any close-up:

Hubble

(and about Sirius A and Sirius B, it is worth noting (for fun) that the former is a dwarf that's white while the latter is a white dwarf, two very different things!)

[Ann]

Speaking of not seeing the forest for the trees, or not seeing the dwarf lenticular galaxy (Bedin 1) for the globular cluster NGC 6752, did you know that for the longest time astronomers didn't see the rich open cluster Gaia 1 because it was lost in the glare of brilliantly bright star Sirius?

Rich open cluster Gaia 1 behind brilliantly bright star Sirius. Credit: H. Kaiser

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ESA wrote:

Dazzling stars like Sirius are both a blessing and a curse for astronomers. Their bright appearance provides plenty of light to study their properties, but also outshines other celestial sources that happen to lie in the same patch of sky.

This is why Sirius has been masked in this picture taken by amateur astronomer Harald Kaiser on 10 January from Karlsruhe, a city in the southwest of Germany.

Once the glare of Sirius is removed, an interesting object becomes visible to its left: the stellar cluster Gaia 1, first spotted last year using data from ESA’s Gaia satellite.

Wikipedia wrote:

Gaia 1 is an open cluster of stars discovered in 2017 by astronomers using data from the Gaia Space Observatory. It is a high-mass and bright cluster, but it remained unseen in prior astronomy due to veiling glare in ordinary telescopes overwhelmed by the star Sirius, which lies 10 arcmins west. Its half-light radius is about 29 light-years (9 pc), assuming a distance of 15,000 light-years (4,600 pc), and it has an estimated mass of about 22,000 M_☉.

Researchers detected the Gaia 1 cluster applying automated "star gauging" to the Gaia observatory's data on star locations. This analysis surprisingly indicated a prominent concentration of stars, previously unknown and uncataloged, adjacent to Sirius. Gaia observed a cluster population of approximately 1,200 stars down to Gaia magnitude 19. Analysis of 2MASS data for those stars shows a red giant branch and a pronounced red clump that allows the absolute magnitude of the stars to be deduced and the distance calculated. Fitting the red giant branch also allows the age of the cluster to be calculated at 6.3 billion years.

Gaia 1 has an estimated mass of 22,000 M_☉, and it is believed to be 6.3 billion years old!!! That's huge! It's like the Double Cluster in Perseus, but the only way the Twins can keep up with Gaia 1 is if you count their huge halos. And NGC 869 and NGC 884 are believed to be only 14 million years old, and open clusters keep shrinking and losing members over time. Gaia 1 is supposedly 6.3 billion years old, making it one of the oldest known clusters of the Milky Way, and it is still as massive - or marginally more massive - than the Double Cluster and their halo put together!

The Double Cluster in Perseus. Credit: Dave & Telescope.

Double Cluster in Perseus, you've got nothing on cluster Gaia 1! Admittedly though, speaking of old open clusters, NGC 6791 is even older:

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According to ESA/Hubble, NGC 6791 is 8 billion years old. An estimate from 2003 claimed that it is 10 billion years old. A really very old publication - from 1965!! - claimed that the mass of NGC 6791 is some 3000 M_☉.

Me, kind of, in 1965:

Whatever! Gaia 1 is a remarkable cluster, and it has been playing hide and seek behind Sirius for as long as humanity has been in possession of telescopes!

Ann

[johnnydeep]

Speaking of not seeing the forest for the trees, or not seeing the dwarf lenticular galaxy (Bedin 1) for the globular cluster NGC 6752, did you know that for the longest time astronomers didn't see the rich open cluster Gaia 1 because it was lost in the glare of brilliantly bright star Sirius?

Rich open cluster Gaia 1 behind brilliantly bright star Sirius. Credit: H. Kaiser

---

ESA wrote:

Dazzling stars like Sirius are both a blessing and a curse for astronomers. Their bright appearance provides plenty of light to study their properties, but also outshines other celestial sources that happen to lie in the same patch of sky.

This is why Sirius has been masked in this picture taken by amateur astronomer Harald Kaiser on 10 January from Karlsruhe, a city in the southwest of Germany.

Once the glare of Sirius is removed, an interesting object becomes visible to its left: the stellar cluster Gaia 1, first spotted last year using data from ESA’s Gaia satellite.

Wikipedia wrote:

Gaia 1 is an open cluster of stars discovered in 2017 by astronomers using data from the Gaia Space Observatory. It is a high-mass and bright cluster, but it remained unseen in prior astronomy due to veiling glare in ordinary telescopes overwhelmed by the star Sirius, which lies 10 arcmins west. Its half-light radius is about 29 light-years (9 pc), assuming a distance of 15,000 light-years (4,600 pc), and it has an estimated mass of about 22,000 M_☉.

Researchers detected the Gaia 1 cluster applying automated "star gauging" to the Gaia observatory's data on star locations. This analysis surprisingly indicated a prominent concentration of stars, previously unknown and uncataloged, adjacent to Sirius. Gaia observed a cluster population of approximately 1,200 stars down to Gaia magnitude 19. Analysis of 2MASS data for those stars shows a red giant branch and a pronounced red clump that allows the absolute magnitude of the stars to be deduced and the distance calculated. Fitting the red giant branch also allows the age of the cluster to be calculated at 6.3 billion years.

Gaia 1 has an estimated mass of 22,000 M_☉, and it is believed to be 6.3 billion years old!!!

...

Ann

I see no cluster to the left of the masked out Sirius, let alone one of 22000 solar masses, but one of the links says this is it. Still looks like nothing much at all to me though!