by Ann » Tue Oct 12, 2010 4:30 pm
That's a lovely image of IC 405/NGC 410 and star asterism "The Leaping Minnow", Alson Wong. This part of the sky is a veritable eldorado for color aficionados, with a smorgasbord of delicious hues.
Compare the two emission nebulae, IC 405 and NGC 410! The large nebula on the right, IC 405, is lit up solely by runaway star AE Aurigae, which is on the lam after breaking out of a starforming region not far from the Trapezium in Orion. So we can conclude that the nebula is at the same distance from us as the star, AE Aurigae, and the star is about 1460 light years away. Note, too, the bluish "filaments" of dust above and to the left of the star. These filaments are dusty blue reflection nebulae, and such features are not normally seen next to stars hot enough to ionize a gas cloud and make it glow red. Because of this dramatic dust, AE Aurigae is also known as The Flaming Star! The dust features are further proof that the star is just passing by, because otherwise the dust would have "evaporated" long ago.
The other nebula, NGC 410, is much farther away. Unlike IC 405, it contains a whole cluster of newborn stars. And there are no blue dust filaments here.
Now look at "The Leaping Minnow", the asterism made up of five stars seemingly positioned between NGC 410 and IC 404. The only yellow star of the lot, 16 Aurigae, is a K3III star, about 235 light years away, about 66 times as bright as the Sun, and with a color index of 1.25, almost exactly the same as Arcturus, although Arcturus not only looks brighter to us in the sky, but it is also intrinsically brighter.
Now, to make things more interesting, let's go to the opposite part of "The Leaping MInnow" and look at the two bluish stars at the top of this asterism. The faintest of these two stars is 18 Aurigae, and just like yellow 16 Aurigae it is about 235 light years away. But 18 Aurigae is no Arcturus, but instead it is a typical Altair! 18 Aurigae is a little "redder" in color than Altair - with a B-V of about 0.256 versus 0.221 for Altair, big difference - but these two stars are almost equally bright, almost exactly 11 times as bright as the Sun.
Oh, but now look at the slightly brighter blue star to the left of 18 Aurigae. That's 19 Aurigae, and it is a tiny bit redder than 18 Aurigae, about 0.287 versus 0.256 for 18 Aurigae. Still 19 is a little hotter than 18, because it is spectral class A5 versus A7 for 18. And 19 is a whopper of a star, too! It's really big! And distant! It may be as far as 3,000 light years away, and it may be as bright as 7,000 times as bright as the Sun!
Now look at the "middle row" of the "Leaping Minnow". The star to the right is the first B-type star we have come across so far, B9.5V 17 Aurigae. It is a little farther away than 16 and 18 Aurigae, but nowhere near as far away as 19. Really this star is typical Vega. Granted, it is a little hotter and bluer than Vega, but just a little, and it is about the same brightness as Vega, about 43 times as bright as the Sun versus around 49 times brighter than the Sun for Vega.
Yes, but now look at the star to the left of 17 Aurigae! It is called IQ Aurigae because it is a variable star, and it looks blue, doesn't it? It sure does, and it
is blue, too. It has a color index that makes all the other stars blush with envy, about
- 0.167! That's blue, let me tell you. Even so this star is classified as an A-type star. Bright Star Catalogues writes about IQ Aurigae:
Magnetic star showing chlorine. Silicon star. Helium and neon deficient. Bluest known peculiar A-star: color characteristic of about B4V. Classified A0p because He weak, but in other respects the color is more indicative of the temperature than teh spectral class of Ap stars. One of the hottest Ap stars known about 17000K.
IQ Aurigae is relatively bright, too, about 111 times as bright as the Sun. It is moderately far away, too, about 450 light years.
Well, IQ Aurigae is one of my favorite stars, as you can guess, and I love that it is set in such a lovely, colorful "neighbourhood", where its own blueness can really shine! And you knew I would say it, I love the
color IQ of this star! Oh, and I love the color IQ and the general picture IQ of your picture too, Alson Wong. You have done a great job bringing out the colors of this delightful region of space, and the composition of your picture is great, too!
Ann
That's a lovely image of IC 405/NGC 410 and star asterism "The Leaping Minnow", Alson Wong. This part of the sky is a veritable eldorado for color aficionados, with a smorgasbord of delicious hues.
Compare the two emission nebulae, IC 405 and NGC 410! The large nebula on the right, IC 405, is lit up solely by runaway star AE Aurigae, which is on the lam after breaking out of a starforming region not far from the Trapezium in Orion. So we can conclude that the nebula is at the same distance from us as the star, AE Aurigae, and the star is about 1460 light years away. Note, too, the bluish "filaments" of dust above and to the left of the star. These filaments are dusty blue reflection nebulae, and such features are not normally seen next to stars hot enough to ionize a gas cloud and make it glow red. Because of this dramatic dust, AE Aurigae is also known as The Flaming Star! The dust features are further proof that the star is just passing by, because otherwise the dust would have "evaporated" long ago.
The other nebula, NGC 410, is much farther away. Unlike IC 405, it contains a whole cluster of newborn stars. And there are no blue dust filaments here.
Now look at "The Leaping Minnow", the asterism made up of five stars seemingly positioned between NGC 410 and IC 404. The only yellow star of the lot, 16 Aurigae, is a K3III star, about 235 light years away, about 66 times as bright as the Sun, and with a color index of 1.25, almost exactly the same as Arcturus, although Arcturus not only looks brighter to us in the sky, but it is also intrinsically brighter.
Now, to make things more interesting, let's go to the opposite part of "The Leaping MInnow" and look at the two bluish stars at the top of this asterism. The faintest of these two stars is 18 Aurigae, and just like yellow 16 Aurigae it is about 235 light years away. But 18 Aurigae is no Arcturus, but instead it is a typical Altair! 18 Aurigae is a little "redder" in color than Altair - with a B-V of about 0.256 versus 0.221 for Altair, big difference - but these two stars are almost equally bright, almost exactly 11 times as bright as the Sun.
Oh, but now look at the slightly brighter blue star to the left of 18 Aurigae. That's 19 Aurigae, and it is a tiny bit redder than 18 Aurigae, about 0.287 versus 0.256 for 18 Aurigae. Still 19 is a little hotter than 18, because it is spectral class A5 versus A7 for 18. And 19 is a whopper of a star, too! It's really big! And distant! It may be as far as 3,000 light years away, and it may be as bright as 7,000 times as bright as the Sun!
Now look at the "middle row" of the "Leaping Minnow". The star to the right is the first B-type star we have come across so far, B9.5V 17 Aurigae. It is a little farther away than 16 and 18 Aurigae, but nowhere near as far away as 19. Really this star is typical Vega. Granted, it is a little hotter and bluer than Vega, but just a little, and it is about the same brightness as Vega, about 43 times as bright as the Sun versus around 49 times brighter than the Sun for Vega.
Yes, but now look at the star to the left of 17 Aurigae! It is called IQ Aurigae because it is a variable star, and it looks blue, doesn't it? It sure does, and it [i]is[/i] blue, too. It has a color index that makes all the other stars blush with envy, about [size=150][color=#4080FF]- 0.167![/color][/size] That's blue, let me tell you. Even so this star is classified as an A-type star. Bright Star Catalogues writes about IQ Aurigae:
[quote]Magnetic star showing chlorine. Silicon star. Helium and neon deficient. Bluest known peculiar A-star: color characteristic of about B4V. Classified A0p because He weak, but in other respects the color is more indicative of the temperature than teh spectral class of Ap stars. One of the hottest Ap stars known about 17000K. [/quote]
IQ Aurigae is relatively bright, too, about 111 times as bright as the Sun. It is moderately far away, too, about 450 light years.
Well, IQ Aurigae is one of my favorite stars, as you can guess, and I love that it is set in such a lovely, colorful "neighbourhood", where its own blueness can really shine! And you knew I would say it, I love the [color=#4080FF][size=150]color IQ[/size][/color] of this star! Oh, and I love the color IQ and the general picture IQ of your picture too, Alson Wong. You have done a great job bringing out the colors of this delightful region of space, and the composition of your picture is great, too!
Ann