Starship Asterisk*

The Tarantula Nebula

Explanation: The Tarantula Nebula is more than a thousand light-years in diameter, a giant star forming region within nearby satellite galaxy the Large Magellanic Cloud, about 180 thousand light-years away. The largest, most violent star forming region known in the whole Local Group of galaxies, the cosmic arachnid sprawls across this spectacular composite view constructed with space- and ground-based image data. Within the Tarantula (NGC 2070), intense radiation, stellar winds and supernova shocks from the central young cluster of massive stars, cataloged as R136, energize the nebular glow and shape the spidery filaments. Around the Tarantula are other star forming regions with young star clusters, filaments, and blown-out bubble-shaped clouds In fact, the frame includes the site of the closest supernova in modern times, SN 1987A, at the lower right. The rich field of view spans about 1 degree or 2 full moons, in the southern constellation Dorado. But were the Tarantula Nebula closer, say 1,500 light-years distant like the local star forming Orion Nebula, it would take up half the sky.

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As I'm watching today's APOD, bursting with weird and vibrant colors, I'm reminded of my childhood, when I used to stare at my parents' print of Vincent van Gogh's painting The Sower, and ask myself, "Why is the sky green?"

Watching today's vibrant APOD, I ask myself, "Why is the Tarantula Nebula yellow?"

As some of you know, colors are exceedingly important to me. In astronomical images, I want colors to represent some sort of "reality". In David Malin's color images from the 1980s, wideband red, green and blue photographic glass plates were used to create very "natural" (if sometimes probably saturated) images. In Hubble's famous Pillars of Creation image, blue color represents OIII emission at 501 nm, green represents Ha at 656 nm, and red represents SII emission at about 672 nm. The longer the wavelength, the redder the mapped color: it makes sense.

Other composite, multiwavelength images are mapped in ways that are far less intuitive, but here the colors are carefully explained.
But I was unable to make sense of the colors in today's APOD until I found the picture at right, made with the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the European Southern Observatory’s site at La Silla, Chile. The filters used for the image were B, V, OIII and H-alpha.









I think the ESO picture of the Tarantula region has been used as a a starting point for today's APOD. The colors in today's APOD are different from the ESO image, but they are clearly influenced by it. The "color weirdness" of today's APOD arises, I think, from the the fact that OIII emission was mapped as yellow-orange and the wideband V image as green in the ESO image. As can be seen in the diagram at left, OIII is a blue-green hue, located at the "blue edge" of the wideband green V filter. It is this mapping of OIII as yellow-orange that creates the strange yellow color of the Tarantula Nebula in today's APOD.

But it is a great image, nevertheless.

Now I only have to figure out why the sky is green in that Vincent van Gogh painting... or else I can enjoy the painting just the way it is.

Ann

Ann wrote:Now I only have to figure out why the sky is green in that Vincent van Gogh painting... or else I can enjoy the painting just the way it is.

Have you seen this article? It seems to indicate that Van Gogh may well have been colour blind, and if his images are filtered to appear as he would have seen them, some of that intense yellow-green becomes a more normal looking yellow.

Or maybe he just knew that the radiation from our Sun peaks in the yellow-green part of the spectrum.

Rob

Ann, the colors are more accurate than you are saying. Below is a visible light version I made for the ESO in 2009 from BVR data recorded by the Danish 1.5M scope at La Silla. The color rendition is similar to my APOD today. Most amateurs use h-alpha to record the Tarantula and in their processing they give excess weight to the 656nm data rendering the complex red. There is considerable OIII emission which when weighted evenly along with the 656nm emission gives the colors you are seeing in today's APOD and my previous ESO image.

https://www.eso.org/public/images/tarantula/


Rob Gendler

Several BVR visible light images with similar colors to today's APOD.

http://www.eso.org/public/images/eso1023a/

https://www.eso.org/public/images/eso0613a/

http://apod.nasa.gov/apod/ap120729.html

While the Tarantula Nebula got its name for resembling the legs of the spider I think it’s the face that stars.

Ann wrote:
Watching today's vibrant APOD, I ask myself,

"Why is the Tarantula Nebula yellow?"

Radioactivity

neufer wrote:

[b][color=#0000FF]The spider bite that gave Peter Parker his powers. Amazing Fantasy #15, art by Steve Ditko.[/color][/b]

---

Ann wrote:
Watching today's vibrant APOD, I ask myself,

"Why is the Tarantula Nebula yellow?"

Radioactivity :?:

Insect?

Guest wrote:Ann, the colors are more accurate than you are saying. Below is a visible light version I made for the ESO in 2009 from BVR data recorded by the Danish 1.5M scope at La Silla. The color rendition is similar to my APOD today. Most amateurs use h-alpha to record the Tarantula and in their processing they give excess weight to the 656nm data rendering the complex red. There is considerable OIII emission which when weighted evenly along with the 656nm emission gives the colors you are seeing in today's APOD and my previous ESO image.

https://www.eso.org/public/images/tarantula/


Rob Gendler

Thanks, Rob. I much prefer the image you linked to.

Ann

Chris Peterson wrote:
Insect?

It's fiction!

bystander wrote:

Chris Peterson wrote:
Insect?

It's fiction!

Fiction? Seriously?

I always thought Spiderman was a real insect.

And yellow.

Ann

wouldn't that be Tarantula Man??

BMAONE23 wrote:wouldn't that be Tarantula Man??

Of course!

Ann

bystander wrote:

Chris Peterson wrote:
Insect?

It's fiction!

• • A Midsummer Night's Dream Act 3, Scene 2
  
  PUCK: Anon his Thisbe must be answered,
  • And forth my mimic comes.

https://en.wikipedia.org/wiki/Spider#Methods_of_capturing_prey wrote:

[b][color=#0000FF][size=150]An ant-mimicking jumping spider[/size][/color][/b]

---

<<Ant-mimicking spiders face several challenges: they generally develop slimmer abdomens and false "waists" in the cephalothorax to mimic the three distinct regions (tagmata) of an ant's body; they wave the first pair of legs in form to their heads to mimic antennae, which spiders lack, and to conceal the fact that they have eight legs rather than six; they develop large color patches round one pair of eyes to disguise the fact that they generally have eight simple eyes, while ants have two compound eyes; they cover their bodies with reflective hairs to resemble the shiny bodies of ants. In some spider species, males and females mimic different ant species, as female spiders are usually much larger than males. Ant-mimicking spiders also modify their behavior to resemble that of the target species of ant; for example, many adopt a zig-zag pattern of movement, ant-mimicking jumping spiders avoid jumping, and spiders of the genus Synemosyna walk on the outer edges of leaves in the same way as Pseudomyrmex. Ant-mimicry in many spiders and other arthropods may be for protection from predators that hunt by sight, including birds, lizards and spiders. However, several ant-mimicking spiders prey either on ants or on the ants' "livestock", such as aphids. When at rest, the ant-mimicking crab spider Amyciaea does not closely resemble Oecophylla, but while hunting it imitates the behavior of a dying ant to attract worker ants. After a kill, some ant-mimicking spiders hold their victims between themselves and large groups of ants to avoid being attacked.>>

I'm curious about the interesting bright object in the upper left of today's image. It seems disconnected from the Tarantula nebula, unlike the various filaments, etc., elsewhere in the image. This is probably just a matter of perception because of it's unique appearance.

neufer wrote:After a kill, some ant-mimicking spiders hold their victims between themselves and large groups of ants to avoid being attacked

Now I know where Hollywood gets its material.

neufer wrote:

bystander wrote:

Chris Peterson wrote:
Insect?

It's fiction!

• • A Midsummer Night's Dream Act 3, Scene 2
  
  PUCK: Anon his Thisbe must be answered,
  • And forth my mimic comes.

https://en.wikipedia.org/wiki/Spider#Methods_of_capturing_prey wrote:

[b][color=#0000FF][size=150]An ant-mimicking jumping spider[/size][/color][/b]

---

<<Ant-mimicking spiders face several challenges: they generally develop slimmer abdomens and false "waists" in the cephalothorax to mimic the three distinct regions (tagmata) of an ant's body; they wave the first pair of legs in form to their heads to mimic antennae, which spiders lack, and to conceal the fact that they have eight legs rather than six; they develop large color patches round one pair of eyes to disguise the fact that they generally have eight simple eyes, while ants have two compound eyes; they cover their bodies with reflective hairs to resemble the shiny bodies of ants. In some spider species, males and females mimic different ant species, as female spiders are usually much larger than males. Ant-mimicking spiders also modify their behavior to resemble that of the target species of ant; for example, many adopt a zig-zag pattern of movement, ant-mimicking jumping spiders avoid jumping, and spiders of the genus Synemosyna walk on the outer edges of leaves in the same way as Pseudomyrmex. Ant-mimicry in many spiders and other arthropods may be for protection from predators that hunt by sight, including birds, lizards and spiders. However, several ant-mimicking spiders prey either on ants or on the ants' "livestock", such as aphids. When at rest, the ant-mimicking crab spider Amyciaea does not closely resemble Oecophylla, but while hunting it imitates the behavior of a dying ant to attract worker ants. After a kill, some ant-mimicking spiders hold their victims between themselves and large groups of ants to avoid being attacked.>>

And the ever popular Jumping Ant Man

dlw wrote:I'm curious about the interesting bright object in the upper left of today's image. It seems disconnected from the Tarantula nebula, unlike the various filaments, etc., elsewhere in the image. This is probably just a matter of perception because of it's unique appearance.

http://apod.nasa.gov/apod/image/1602/Ta ... ed1800.jpg

It's labeled N 161 on the annotation and I am also curious in which catalog it may be listed. I suspect the "annotater" might know?

Fred the Cat wrote:

dlw wrote:I'm curious about the interesting bright object in the upper left of today's image. It seems disconnected from the Tarantula nebula, unlike the various filaments, etc., elsewhere in the image. This is probably just a matter of perception because of it's unique appearance.

http://apod.nasa.gov/apod/image/1602/Ta ... ed1800.jpg

It's labeled N 161 on the annotation and I am also curious in which catalog it may be listed. I suspect the "annotater" might know?

It might be more properly labeled LHA 120-N 161. LHA 120 meaning Lamont-Hussey alpha, field 120. N simply means nebula.
http://cdsads.u-strasbg.fr/abs/1956ApJS....2..315H
http://cdsads.u-strasbg.fr/abs/1967SAOP.4699....1H
https://en.wikipedia.org/wiki/Lamont%E2 ... bservatory

I thought that meant Henize. Thanks geckzilla.

BMAONE23 wrote:

https://en.wikipedia.org/wiki/Spider#Methods_of_capturing_prey wrote:

[b][color=#0000FF][size=150]An ant-mimicking jumping spider[/size][/color][/b]

---

<<Ant-mimicking spiders face several challenges: they generally develop slimmer abdomens and false "waists" in the cephalothorax to mimic the three distinct regions (tagmata) of an ant's body; they wave the first pair of legs in form to their heads to mimic antennae, which spiders lack, and to conceal the fact that they have eight legs rather than six; they develop large color patches round one pair of eyes to disguise the fact that they generally have eight simple eyes, while ants have two compound eyes; they cover their bodies with reflective hairs to resemble the shiny bodies of ants. In some spider species, males and females mimic different ant species, as female spiders are usually much larger than males. Ant-mimicking spiders also modify their behavior to resemble that of the target species of ant; for example, many adopt a zig-zag pattern of movement, ant-mimicking jumping spiders avoid jumping, and spiders of the genus Synemosyna walk on the outer edges of leaves in the same way as Pseudomyrmex. Ant-mimicry in many spiders and other arthropods may be for protection from predators that hunt by sight, including birds, lizards and spiders. However, several ant-mimicking spiders prey either on ants or on the ants' "livestock", such as aphids. When at rest, the ant-mimicking crab spider Amyciaea does not closely resemble Oecophylla, but while hunting it imitates the behavior of a dying ant to attract worker ants. After a kill, some ant-mimicking spiders hold their victims between themselves and large groups of ants to avoid being attacked.>>

And the ever popular Jumping Ant Man [/quote]
I have nothing to add about the Ant Man, but just yesterday a specimen of zodarion rubidium, known in English as ant spider, was found for the first time ever in Sweden. It was found in my hometown of Malmö.

Ants and spiders, unite!

Ann