by alter-ego » Wed Dec 01, 2021 5:25 am
VictorBorun wrote: ↑Tue Nov 30, 2021 7:57 am
wiki says LL Pegasi is even farther away, 1,300 pc
I took the 1kpc at face value, on the basis of mass outflow velocity, and the 700 yr to 800 yr shell separation. With that said, I would tend to give the newer Wiki estimate more credence.
I wonder how far it is from the disk of Milky Way and what bright stars are main illuminators
The caption in Fig. 1 (the aforementioned paper) says the galactic plane is 650pc away.
It's a surprise for me to know how dense the soot around a carbon red giant is, to cover it and its companion so thick that the Milky Way (dominating the starry sky outside the galaxy disk) is brighter than the stars within the shells.
Yeah, it's dense, as indicated by Keck's and ALMA images, but still, it seems that the supposed blue companion should be noticeable. On the other hand, the spiral's one-sided illumination also looks convincingly like an external source. Considering the 3D aspects, maybe the scattered light is escaping at lower latitudes with much less escaping out the nebula's poles. Like Chris said, it is odd why spectra measurements haven't resolved this. Interesting it is.
Compare with an observer at Kuiper belt. There is our Sun, there are Sirius and Vega. The Milky Way is not dominating at all as a lamp for Pluto's hills.
Well, our solar system literally has no extinction relative to LL Pegasi. From Pluto, the Sun's brightness is not noticeably attenuated, it's magnitude is about -19, so clearly the Sun dominates over all other light sources. The
Integrated Flux Neblua is an example of nebula structures illuminated by stars in the galactic plane. I don't have a sense though if conditions are comparable to the spiral nebula.
[quote=VictorBorun post_id=318660 time=1638259056 user_id=145500]
wiki says LL Pegasi is even farther away, 1,300 pc[/quote]
I took the 1kpc at face value, on the basis of mass outflow velocity, and the 700 yr to 800 yr shell separation. With that said, I would tend to give the newer Wiki estimate more credence.
[quote]I wonder how far it is from the disk of Milky Way and what bright stars are main illuminators[/quote]
The caption in Fig. 1 (the aforementioned paper) says the galactic plane is 650pc away.
[quote]It's a surprise for me to know how dense the soot around a carbon red giant is, to cover it and its companion so thick that the Milky Way (dominating the starry sky outside the galaxy disk) is brighter than the stars within the shells. [/quote]
Yeah, it's dense, as indicated by Keck's and ALMA images, but still, it seems that the supposed blue companion should be noticeable. On the other hand, the spiral's one-sided illumination also looks convincingly like an external source. Considering the 3D aspects, maybe the scattered light is escaping at lower latitudes with much less escaping out the nebula's poles. Like Chris said, it is odd why spectra measurements haven't resolved this. Interesting it is.
[quote]Compare with an observer at Kuiper belt. There is our Sun, there are Sirius and Vega. The Milky Way is not dominating at all as a lamp for Pluto's hills.[/quote]
Well, our solar system literally has no extinction relative to LL Pegasi. From Pluto, the Sun's brightness is not noticeably attenuated, it's magnitude is about -19, so clearly the Sun dominates over all other light sources. The [url=https://en.wikipedia.org/wiki/Integrated_Flux_Nebula]Integrated Flux Neblua[/url] is an example of nebula structures illuminated by stars in the galactic plane. I don't have a sense though if conditions are comparable to the spiral nebula.