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APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 4:06 am
by APOD Robot
Barnard 228: The Dark Wolf Nebula in Lupus
Explanation: These
dark markings on the sky can just be found in silhouette against a rich, luminous background of stars. Seen toward the southern constellation of Lupus the Wolf, the dusty, obscuring clouds are part of the Lupus Molecular Cloud some 500 light-years distant. Packs of low mass stars are forming
within them, from collapsing cores only visible at long
infrared wavelengths. Still, colorful stars in Lupus add to this
pretty galactic skyscape. It spans about 8 degrees, not far from the central Milky Way.
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 11:40 am
by heehaw
"can just be found in silhouette against a rich, luminous background of stars" Yes, when I recently saw the first Gaia "images" :
http://sci.esa.int/gaia/60169-gaia-s-sky-in-colour/ I was puzzled that I could see the dark interstellar clouds! Gaia only detects stars!
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 12:42 pm
by astromaster
I discuss this region in my June 2017 Sky & Telescope article "The Dark Wolf of Summer!" Barnard 228 is, of course, the main object in view and could be subdivided into Sandqvist Lindroos 12 and 13. The most significant object left out of the discussion, however, is Bernes 148 (also known as Parsamian Petrosian 81 - PP81 - or GN 15.42.0. This is a bright nebula seen in the left center of the image at 8th magnitude in a spot just above the two brightest stars and has 4 10th magnitude stars in an arc above it. It is interesting as a typical nebula covering double variable stars HT and HW Lupus each with a brightness of 10th magnitude. At 8th magnitude this is a nebula that is easily observable in any telescope if one has a dark sky. Richard P. Wilds
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 12:53 pm
by neufer
https://en.wikipedia.org/wiki/%C3%89tienne_de_Silhouette wrote:
<<Étienne de Silhouette (5 July 1709 – 20 January 1767) was a French Ancien Régime Controller-General of Finances under Louis XV. In an attempt to restore the kingdom's finances by the English method of taxing the rich and privileged de Silhouette devised the "general subvention," i.e., taxes on external signs of wealth (doors and windows, farms, luxury goods, servants, profits). His penny-pinching manner led the term à la Silhouette to be applied to things perceived as cheap or austere.
During this period an art form of growing popularity was a shadow profile cut from black paper. It provided a simple and inexpensive alternative for those who could not afford more decorative and expensive forms of portraiture, such as painting or sculpture. Those who considered it cheap attached the word "silhouette" to it.>>
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 1:01 pm
by astromaster
You can also obtain information on this topic in my new book: Check out my new 630 page book, Bright and Dark Nebulae: An Observers Guide to Understanding the Clouds of the Milky Way Galaxy, CreateSpace, 2017 via
https://www.createspace.com/7355429
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 2:35 pm
by Chris Peterson
heehaw wrote: ↑Thu Jul 26, 2018 11:40 am
"can just be found in silhouette against a rich, luminous background of stars" Yes, when I recently saw the first Gaia "images" :
http://sci.esa.int/gaia/60169-gaia-s-sky-in-colour/ I was puzzled that I could see the dark interstellar clouds! Gaia only detects stars!
Where I live there is no light pollution. On a dark night, there's not enough light from the ground to make clouds visible. I have an automated camera that evaluates the sky for imaging potential. It works by looking for an absence of stars.
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 5:39 pm
by De58te
Cool. So this dark cloud is only 500 light years away. Closer to us than the star Betelgeuse, and the belt stars in Orion are actually twice as far away! I wonder if this looks like the dust nebula the Sun formed in all those billions of years ago? Could the Sun actually have formed there and then shot away by some repulsive force? Wonder if somebody has any measurements showing the Sun is moving away from the Wolf?
Re: APOD: Barnard 228: The Dark Wolf Nebula in... (2018 Jul 26)
Posted: Thu Jul 26, 2018 9:11 pm
by MarkBour
De58te wrote: ↑Thu Jul 26, 2018 5:39 pm
Cool. So this dark cloud is only 500 light years away. Closer to us than the star Betelgeuse, and the belt stars in Orion are actually twice as far away! I wonder if this looks like the dust nebula the Sun formed in all those billions of years ago? Could the Sun actually have formed there and then shot away by some repulsive force? Wonder if somebody has any measurements showing the Sun is moving away from the Wolf?
Interesting hypothesis.
Here's an article on the search.
https://sydney.edu.au/news-opinion/news ... lings.html
One star has been matched as being a likely "sibling" for the Sun. HD 162826 in Hercules (
https://en.wikipedia.org/wiki/HD_162826).