Starship Asterisk*

Wow, that's Jimmy Walker the multi-title winning golf pro! He sure can afford to buy that top gear :D

[list][b]Troilus and Cressida Act 1, Scene 3[/b][/list]
[b]ULYSSES: [i][color=#0000FF]For that will physic the great Myrmidon
[list] Who broils in loud applause, and make him fall
His crest that prouder than blue Iris bends.[/color][/list][/i][/b]

[quote="Ann"][quote]starsurfer wrote:
I find it strange that every amateur image of the Iris Nebula is LRGB only with no Ha.[/quote]

I see your point, starsurfer. But bear in mind that HD 200775, the star illuminating this nebula, is of spectral class B2. That's enough to create some Ha emission in the surrounding nebula, but not a lot of it. NGC 7023 is primarily a blue reflection nebula, and I for one am very happy to see it as such.

Ann[/quote]
I'm also happy to see it as blue but adding hydrogen alpha data would not make it less blue. I remember seeing a Ha image of the Iris Nebula in a scientific paper once but I can't seem to find it now. Also Ha would show recently discovered Herbig Haro objects.

Also what are your feelings towards purple nebulae?

Lovely photo! We watched a lecture from Professor Carolin Crawford at Gresham this evening about star dust and the Iris Nebula was used as a beautiful example.

http://www.youtube.com/watch?v=YvuGK-Y_qzk

Always a wonderful sight.

We get MOON shots that kind of look like that, with a Moon Aura, peeking through some clouds....

:---[===] *

[quote]starsurfer wrote:
I find it strange that every amateur image of the Iris Nebula is LRGB only with no Ha.[/quote]

I see your point, starsurfer. But bear in mind that HD 200775, the star illuminating this nebula, is of spectral class B2. That's enough to create some Ha emission in the surrounding nebula, but not a lot of it. NGC 7023 is primarily a blue reflection nebula, and I for one am very happy to see it as such.

Ann

[quote="Ann"]Oh, that's a lovely picture of one of my favorite nebulas! Note the intricate structure of the dusty tendrils near the illuminating star, HD 200775. Note how the color changes from clear blue inside the central butterfly-shaped "clearing" into ever grayer and browner shades as the dust takes over farther from the star. Note the hints of pink Ha-emission from eroding "walls" of dust close to the star, which take the full brunt of ultraviolet light from that hot blue stellar furnace.

What a lovely image!

Ann[/quote]
I find it strange that every amateur image of the Iris Nebula is LRGB only with no Ha.

Thank you Jimmy Walker , what a beautiful image.

[quote="ShaileshS"]How common/rare it is to have a nebula surrounding hot young blue star ? I was of the impression that most times, the nebula would be what we see the remnants (outer layers burst from explosion) of supernova with pale while dying star in the center .. No ?[/quote]
Such nebulas are very common.

Nebulas can be broadly placed into two categories: those from which new stars are forming, or recently formed (like today's subject), and those which were ejected from stars late in their evolution.

How common/rare it is to have a nebula surrounding hot young blue star ? I was of the impression that most times, the nebula would be what we see the remnants (outer layers burst from explosion) of supernova with pale while dying star in the center .. No ?

Beautiful Iris Nebula! 8-)

Oh, that's a lovely picture of one of my favorite nebulas! Note the intricate structure of the dusty tendrils near the illuminating star, HD 200775. Note how the color changes from clear blue inside the central butterfly-shaped "clearing" into ever grayer and browner shades as the dust takes over farther from the star. Note the hints of pink Ha-emission from eroding "walls" of dust close to the star, which take the full brunt of ultraviolet light from that hot blue stellar furnace.

What a lovely image!

Ann

[url=http://apod.nasa.gov/apod/ap140802.html][img]http://apod.nasa.gov/apod/calendar/S_140802.jpg[/img] [size=150]NGC 7023: The Iris Nebula[/size][/url]

[b] Explanation: [/b] These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the [url=http://hawastsoc.org/deepsky/cep/index.html]constellation Cepheus[/url]. Sometimes called the Iris Nebula, [url=http://www.universetoday.com/17597/ngc-7023-iris-from-the-dust-by-kent-wood/]NGC 7023[/url] is not the only nebula in the sky to evoke the imagery [url=http://apod.nasa.gov/apod/ap080214.html]of flowers[/url], though. Still, this [url=http://jwalk.smugmug.com/Photography/AstroPhotos/i-BFcpm29/A]deep telescopic view[/url] shows off the Iris Nebula's range of colors and symmetries in impressive detail. [url=http://www.spacetelescope.org/videos/heic0915b/]Within the Iris[/url], dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, [url=http://leo.astronomy.cz/mix/mix.html]characteristic of dust[/url] grains reflecting starlight. [url=http://www.spacetelescope.org/news/heic0915/]Central filaments[/url] of the dusty clouds glow with a faint reddish photoluminesence as some dust grains [url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1989ApJ...347L..25W&db_key=AST&high=3bc4bede8e21358]effectively convert[/url] the star's invisible [url=http://imagers.gsfc.nasa.gov/ems/uv.html]ultraviolet[/url] radiation to visible red light. Infrared [url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2000A%26A...354L..17M&db_key=AST&nosetcookie=1]observations[/url] indicate that this nebula may contain complex carbon molecules known as [url=http://legacy.spitzer.caltech.edu/features/articles/20050627.shtml]PAHs[/url]. The pretty blue petals of the Iris Nebula span about six light-years.

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