APOD: The Helix Nebula in Infrared (2016 Sep 20)

[APOD Robot]

The Helix Nebula in Infrared

Explanation: What makes this cosmic eye look so red? Dust. The featured image from the robotic Spitzer Space Telescope shows infrared light from the well-studied Helix Nebula (NGC 7293) a mere 700 light-years away in the constellation of the Water Carrier Aquarius. The two light-year diameter shroud of dust and gas around a central white dwarf has long been considered an excellent example of a planetary nebula, representing the final stages in the evolution of a Sun-like star. But the Spitzer data show the nebula's central star itself is immersed in a surprisingly bright infrared glow. Models suggest the glow is produced by a dust debris disk. Even though the nebular material was ejected from the star many thousands of years ago, the close-in dust could have been generated by collisions in a reservoir of objects analogous to our own solar system's Kuiper Belt or cometary Oort cloud. Had the comet-like bodies formed in the distant planetary system, they would have survived even the dramatic late stages of the star's evolution.

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[Ann]

Geck, exactly what do the colors mean?

I guess they have to do with temperature. Does that mean, though, that the dust closer to the hot star is cooler (and therefore redder) than the dust in the visible thick dust ring surrounding the inner "cavity"?

Ann

[geckzilla]

Yes, the 24 micron interior, which is red, is the warm dust. The browner parts, between 8 and 5.8 microns, are the cooler dust. Stars without or with little dust tend to shine at the shortest wavelengths, 4.5 and 3.6 microns, appearing cyan and blue. I'm not exactly sure about the nature of all the red dots surrounding the nebula. I want to say they're unrelated stars, but later on when I processed more Spitzer data, there weren't a lot of point sources like that again. Maybe they are actually parts of the nebula, or maybe I need to study more infrared data.

[rwinrich@sbcglobal.net]

Would such an expansion have ejected what ever cometary bodies existed in that region and left them to wander in interstellar space?

[neufer]

Would such an expansion have ejected what ever cometary bodies existed in that region and left them to wander in interstellar space?

An object in a circular orbit around a star has only half the kinetic energy it needs to escape the star's potential well. Hence, a full half of the stellar material needs to blow by it in order for the object to escape.

However, an object in a near parabolic orbit has practically all the kinetic energy it needs to escape the star's potential well. Since a comet is in a near parabolic orbit near perihelion only a small fraction [i.e., specifically: (r/2a)] of the stellar material needs to blow by it in order for the comet to escape.

Therefore, comets near perihelion would be the first rats off the ship.

However, on average comets (which spend most of there time near aphelion) would be the last rats off the ship since more than half [i.e., specifically: (1 + e²/2)/2] of the stellar material needs to blow by them in order for the comets to escape. (Since the solar wind will most likely extend over many orbits this is the situation to consider.)

<<It is often said that the semi-major axis is the "average" distance between the primary focus of the ellipse and the orbiting body. This is not quite accurate, because it depends on what the average is taken over.

• 1) averaging the distance over the eccentric anomaly (q.v.) indeed results in the semi-major axis "a".
  
  2) averaging over the mean anomaly (the fraction of the orbital period that has elapsed since pericentre, expressed as an angle), finally, gives the time-average:
  

  

  ---

[Boomer12k]

Wow....Awesome...

:---[===] *

[Boomer12k]

Yes, the 24 micron interior, which is red, is the warm dust. The browner parts, between 8 and 5.8 microns, are the cooler dust. Stars without or with little dust tend to shine at the shortest wavelengths, 4.5 and 3.6 microns, appearing cyan and blue. I'm not exactly sure about the nature of all the red dots surrounding the nebula. I want to say they're unrelated stars, but later on when I processed more Spitzer data, there weren't a lot of point sources like that again. Maybe they are actually parts of the nebula, or maybe I need to study more infrared data.

I looked at other IR shots. I think whatever you did, created some of them, they are not in the other shot...such as this one....http://quantum-cosmos.com/blog/2011/05/ ... -darkness/.... about 3/4 down the page. As you turned things another color...other things of that color can change too... even though not noticeable at the time. So, you might get small blobs. In the QC.com shot, there is a rather large red blob near the upper left of the "Eye"... where the arc begins. It is barely visible in yours. There are these things in the other shot, but they are brought out more in yours. I think they are of the Nebula, and not background stars, or foreground stars...so, I think it is your process....like when turning up the contrast and sharpness, etc...

Simply my opinion...Still AWESOME looking...
:---[===] *

[geckzilla]

I looked at other IR shots. I think whatever you did, created some of them, they are not in the other shot...such as this one....http://quantum-cosmos.com/blog/2011/05/ ... -darkness/.... about 3/4 down the page. As you turned things another color...other things of that color can change too... even though not noticeable at the time. So, you might get small blobs. In the QC.com shot, there is a rather large red blob near the upper left of the "Eye"... where the arc begins. It is barely visible in yours. There are these things in the other shot, but they are brought out more in yours. I think they are of the Nebula, and not background stars, or foreground stars...so, I think it is your process....like when turning up the contrast and sharpness, etc...

Simply my opinion...Still AWESOME looking...
:---[===] *

I definitely didn't create any of them. Whatever you see in there is in the data, though they are sharpened a bit. The MIPS24 data is significantly lower resolution, so small sources appear more extended and fuzzy. The red blob you mention from the other image is simply not in the supermosaic data I used. I did look up the rest of the data to see which it is contained in and I see it in the 2004.839790 Epoch image. It is a transient event and I am under the impression it is a cosmic ray.

Edit: I looked at the MIPS channel and it looks more clearly like they are unrelated stars to me. Note that the band of stars which look slightly brighter across the center are a result of me trying to even the brightness of the sky across the image. Originally there was a large swath of darker sky going across it.

Data represented by red in the APOD image

[Fred the Cat]

What a new look for a much seen object. And only 700 light years away. Some day our future civilization may take the "red eye" there to peer into its secrets

[neufer]

The Helix nebula is similar to what our Sun will produce in 8 billion years.

<<Once the Sun changes from burning hydrogen at its core to burning hydrogen around its shell, the core will start to contract and the outer envelope will expand. The total luminosity will steadily increase over the following billion years until it reaches 2,730 times the Sun's current luminosity at the age of 12.167 billion years. Most of Earth's atmosphere will be lost to space and its surface will consist of a lava ocean with floating continents of metals and metal oxides as well as icebergs of refractory materials, with its surface temperature reaching more than 2,400 K. The Sun will experience more rapid mass loss, with about 33% of its total mass shed with the solar wind. The loss of mass will mean that the orbits of the planets will expand. The orbital distance of the Earth will increase to at most 150% of its current value.

The most rapid part of the Sun's expansion into a red giant will occur during the final stages, when the Sun will be about 12 billion years old. It is likely to expand to swallow both Mercury and Venus, reaching a maximum radius of 1.2 AU. The Earth will interact tidally with the Sun's outer atmosphere, which would serve to decrease Earth's orbital radius. Drag from the chromosphere of the Sun would also reduce the Earth's orbit. These effects will act to counterbalance the effect of mass loss by the Sun, and the Earth will probably be engulfed by the Sun.

The drag from the solar atmosphere may cause the orbit of the Moon to decay. Once the orbit of the Moon closes to a distance of 18,470 km, it will cross the Earth's Roche limit. This means that tidal interaction with the Earth would break apart the Moon, turning it into a ring system. Most of the orbiting ring will then begin to decay, and the debris will impact the Earth. Hence, even if the Earth is not swallowed up by the Sun, the planet may be left moonless. The ablation and vaporization caused by its fall on a decaying trajectory towards the Sun may remove Earth's crust and mantle, then finally destroy it after at most 200 years. Following this event, Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity.>>

[ems57fcva]

If you zoom in on the center, you see bright dots with what look like cometary tails coming off of them. One is a 1:00 from the central star, and others are at 2:30, 3:00, and 7:30. Perhaps we are seeing a cometary system being destroyed by the young white dwarf at the center.

[Fred the Cat]

If you zoom in on the center, you see bright dots with what look like cometary tails coming off of them. One is a 1:00 from the central star, and others are at 2:30, 3:00, and 7:30. Perhaps we are seeing a cometary system being destroyed by the young white dwarf at the center.

Makes you ask when the comet got the message from "gravity-central" that the star wasn't in Kansas anymore.

[ta152h0]

" here is looking at you "

[BillBixby]

Catching the Red Eye back to Earth from the Asterisk.

[moonshiner]

The red glow in image of Helix Nebula reminds me of the color of rosea wine I occassionally check for acidity and aroma. The image is in infrared so that one would have to check with calibrarion info of the Spitzer telescope to identify the temperature at which the glowing region shines. It must be very hot, probably in the millions of degrees celcius. But the region in question is about a light year accross. That should tell me something about the vast amount of energy being radiated into the glowing region from central star. Spectral analysis of glowing region should identify chemical composition of molecule and ion in that region; I recall that oxygen was the main element in that region as identified in former surveys. The central star, or stellar core, is interesting for two reasons: it is stable and it is white hot. The term stellar core probably describes the central stellar object more completely.
However, it is not an active object such as a neutron star or pulsar. The Helix Nebula appears to be more closely related to objects like the Ring Nebula in terms of structure and composition. The optical image of the Helix Nebula is more informative because it helps to relate various aspects of an object within a certain perspective into recognisable form. The Helix experience is special because it gives a glimpse into the processes of stellar evolution. However, textbook models may not be relied upon to give an account of the mechanics of stellar dynamics as witnessed in the Helix Nebula. Millions of years from now, the glowing mass will probably fall back onto the stellar core building up a Sun-like star and an array of planets. There will probably be terrestrial planets and gaseous planets, some of which will be gas giants, and a cosmic sphere of comets and asteroids like the one that accompanies the star Epsilon Eridani or Tau Ceti.

[Chris Peterson]

The image is in infrared so that one would have to check with calibrarion info of the Spitzer telescope to identify the temperature at which the glowing region shines. It must be very hot, probably in the millions of degrees celcius

IR emissions peak at cool temperatures. The 21 um filter is centered on 120 K emissions. The 8 um filter is about 350 K. The shortest wavelength filter, 3.6 um, is about 800 K. So we're looking a temperature range here from icy comets to pizza ovens.

[geckzilla]

In astronomical terms I tend to not think of anything as hot until it's emitting gamma or x-rays. Hehe