by Ann » Thu Nov 07, 2019 6:41 am
Who isn't happy to see the Pleiades as an APOD?
And I for mine am very happy to see Adam Block get another APOD!
This particular picture of the Pleiades is very deep and wide, and it reveals lots of nebulosity outside the most recognizable outline of the Pleiades. The nebulosity comes in different colors, yellowish, faintly reddish, and blue. Most of the blue nebulosity that is disconnected from the recognaizable outline of the Pleiades is seen to the left of the Pleiades in this picture (actually to the north of this iconic cluster).
Fascinatingly, though, the star that is most deeply immersed in blue nebulosity outside the Pleiades (a star at 8 o'clock) has a much larger parallax than the stars of the Pleiades. Judging from its parallax, this star, HD 23985, is less than half as far away as the Pleiades, less than 200 light-years for this star versus more than 400 light-years for the Pleiades!
Fascinating! Do I take this to mean that the dust cloud that the Pleiades are immersed in is more than 200 light-years deep? So that the Pleiades and HD 23985 are immersed in different ends of one admittedly somewhat broken huge dust cloud?
Apart from HD 23985, most of the blue stars in Adam Block's picture have similar parallaxes and similar proper motions as the most iconic Pleiades. So the actual Pleiades cluster extends well beyond its most iconic outline.
- The Pleiades small.png (352.18 KiB) Viewed 3564 times
Who isn't happy to see the Pleiades as an APOD? :D
And I for mine am very happy to see Adam Block get another APOD! :D
This particular picture of the Pleiades is very deep and wide, and it reveals lots of nebulosity outside the most recognizable outline of the Pleiades. The nebulosity comes in different colors, yellowish, faintly reddish, and blue. Most of the blue nebulosity that is disconnected from the recognaizable outline of the Pleiades is seen to the left of the Pleiades in this picture (actually to the north of this iconic cluster).
Fascinatingly, though, the star that is most deeply immersed in blue nebulosity outside the Pleiades (a star at 8 o'clock) has a much larger parallax than the stars of the Pleiades. Judging from its parallax, this star, HD 23985, is less than half as far away as the Pleiades, less than 200 light-years for this star versus more than 400 light-years for the Pleiades!
Fascinating! Do I take this to mean that the dust cloud that the Pleiades are immersed in is more than 200 light-years deep? So that the Pleiades and HD 23985 are immersed in different ends of one admittedly somewhat broken huge dust cloud?
Apart from HD 23985, most of the blue stars in Adam Block's picture have similar parallaxes and similar proper motions as the most iconic Pleiades. So the actual Pleiades cluster extends well beyond its most iconic outline.
[attachment=0]The Pleiades small.png[/attachment]