APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

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APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by APOD Robot » Mon Sep 03, 2012 4:06 am

Image M45: The Pleiades Star Cluster

Explanation: Perhaps the most famous star cluster on the sky, the Pleiades can be seen without binoculars from even the depths of a light-polluted city. Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and closest open clusters. The Pleiades contains over 3000 stars, is about 400 light years away, and only 13 light years across. Quite evident in the above photograph are the blue reflection nebulae that surround the brighter cluster stars. Low mass, faint, brown dwarfs have also been found in the Pleiades. (Editors' note: The prominent diffraction spikes are caused by the telescope itself and may be either distracting or provide aesthetic enhancement, depending on your point of view.)

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Beyond » Mon Sep 03, 2012 4:18 am

Today's APOD must be a family portrait that includes cousins, because i can't tell which ones are the 7-sisters. :lol2:
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Chris Peterson » Mon Sep 03, 2012 4:21 am

Beyond wrote:Today's APOD must be a family portrait that includes cousins, because i can't tell which ones are the 7-sisters. :lol2:
Most people see six naked eye Pleiades. Those with sharper vision normally see eight or nine. Almost nobody sees seven. Through a pair of binoculars there are dozens.
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Beyond » Mon Sep 03, 2012 4:28 am

Well how the heck come they're called the 7-sisters, then :?:
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Boomer12k » Mon Sep 03, 2012 4:30 am

Ann must be in Blue Heaven... :D

Just an AWESOME Picture...THANKS.


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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by bystander » Mon Sep 03, 2012 4:32 am

Beyond wrote:Well how the heck come they're called the 7-sisters, then :?:
Because that's what the Pieiades are, the seven daughters of Atlas and Pleione.
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Chris Peterson » Mon Sep 03, 2012 4:39 am

bystander wrote:
Beyond wrote:Well how the heck come they're called the 7-sisters, then :?:
Because that's what the Pieiades are, the seven daughters of Atlas and Pleione.
No, I don't think that's really it. Other cultures, having no connection with Greek mythology, have also seen this as a constellation of seven stars. I think it's more related to the fact that seven is seen as a "special" number, with mystical properties (which is probably the root of the count of sisters in the Greek myth, as well).
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Beyond » Mon Sep 03, 2012 5:15 am

I figured it was something 'strange', like that.
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by ta152h0 » Mon Sep 03, 2012 6:40 am

my vote - not a painting ! pass the ice cold one please !
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by neufer » Mon Sep 03, 2012 6:44 am

Chris Peterson wrote:
bystander wrote:
Beyond wrote:
Well how the heck come they're called the 7-sisters, then :?:
Because that's what the Pleiades are,
the seven daughters of Atlas and Pleione.
No, I don't think that's really it. Other cultures, having no connection with Greek mythology, have also seen this as a constellation of seven stars. I think it's more related to the fact that seven is seen as a "special" number, with mystical properties (which is probably the root of the count of sisters in the Greek myth, as well).
  • [list]King Lear Act I, scene V
Fool: The reason why the seven stars are no more than seven is a pretty reason.

KING LEAR: Because they are not eight?

Fool: Yes, indeed: thou wouldst make a good fool.[/color][/size][/list]
http://en.wikipedia.org/wiki/Pleiades_in_folklore_and_literature wrote:
<<A Cheyenne myth "The Girl Who Married a Dog", states that the group of seven stars known as the Pleiades originated from seven puppies which a Cheyenne chief's daughter gave birth to after mysteriously being visited by a dog in human form to whom she vowed "Wherever you go, I go". The Lakota Tribe of North America had a legend that linked the origin of the Pleiades to Devils Tower. According to the Seris (of northwestern Mexico), these stars are seven women who are giving birth.

In a legend told by the Wurundjeri people of south-eastern Australia, the Pleiades were represented by the seven Karatgurk sisters. These women were the first to possess the secret of fire and each one carried live coals on the end of her digging stick. Although they refused to share these coals with anybody, they were ultimately tricked into giving up their secret by Crow, who subsequently brought fire to mankind. After this, the Karatgurk sisters were swept into the night sky. Their glowing fire sticks became the bright stars of the Pleiades cluster.

Another version depicts the story of seven Napaltjarri sisters being chased by a man named Jilbi Tjakamarra. He tried to practice love magic to one of the sisters but the sister did not want to be with him and with her sisters, they ran away from him. They sat down at Uluru to search for honey ants but when they saw Jilbi, they went to Kurlunyalimpa and with the spirits of Uluru, transformed into stars. Jilbi transforms himself into what is commonly known as the Morning Star in Orion's belt, thus continuing to chase the seven sisters across the sky.

In Thailand, the Pleiades are known as the "Chicken Family Stars," and there are folk tales about them: The elderly couple who lived amidst a forest in Thailand raised a family of chickens: a mother hen and her six children. One day a monk arrived at the elderly couple's home during his Dhutanga journey. Afraid that they have no decent meals to offer him, the elderly couple contemplated cooking the mother hen. Overheard the conversation, the mother hen rushed back to the coop to say farewell to her children. She asked them to take care of themselves before leaving to repay the kindness of the elderly couple. As the mother hen was being killed, her six children threw themselves into fire to die alongside with their mother. Deity, impressed by and in remembrance of their love, immortalized the seven chickens as the stars.

In Theosophy, it is believed the Seven Stars of the Pleiades focus the spiritual energy of the Seven Rays from the Galactic Logos to the Seven Stars of the Great Bear, then to Sirius, then to the Sun, then to the god of Earth (Sanat Kumara) and finally through the seven Masters of the Seven Rays to us.

In Ufology some believers describe Nordic alien extraterrestrials (called Pleiadeans) as originating from this system.>>
Last edited by neufer on Mon Sep 03, 2012 7:31 am, edited 2 times in total.
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by ta152h0 » Mon Sep 03, 2012 6:55 am

wow !! Just struck me tonight the ancient egyptians were great capitalists. Cheaper to build three pyramids than to build 7 !
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Ann » Mon Sep 03, 2012 8:27 am

Boomer12k wrote:Ann must be in Blue Heaven... :D

Just an AWESOME Picture...THANKS.


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The Pleiades is the loveliest, visually bluest, best-recognized and most beloved star cluster in the sky. Nuff said!

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by ritwik » Mon Sep 03, 2012 9:29 am

Image

a little recognition for a speck of light :ssmile:

thanks
no copyright right infringement intended

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by orin stepanek » Mon Sep 03, 2012 12:23 pm

Beyond wrote:Well how the heck come they're called the 7-sisters, then :?:
They have another name! >> Subaru! 8-) :D
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Ann » Mon Sep 03, 2012 12:37 pm

orin stepanek wrote:
Beyond wrote:Well how the heck come they're called the 7-sisters, then :?:
They have another name! >> Subaru! 8-) :D
Not many star clusters can drive their own cars!

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Tszabeau » Mon Sep 03, 2012 12:47 pm

Perhaps it should be called the Seven Dwarves since, there are actual brown dwarfs among the non-existent sisters. Speaking of brown dwarfs, does anyone know if they only form in orbit around fully developed stars or can they form on their own? Do they, in-turn have orbiting planets?

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by neufer » Mon Sep 03, 2012 2:22 pm

Tszabeau wrote:
Perhaps it should be called the Seven Dwarves since, there are actual brown dwarfs among the non-existent sisters.
  • There are more than seven known Pleiades sisters and less than seven known Pleiades dwarfs.
http://en.wikipedia.org/wiki/Teide_1 wrote:

<<Teide 1 was the first brown dwarf to be verified, in 1995. It is located in the Pleiades open star cluster, approximately 400 light years from Earth. The apparent magnitude of this faint object is 17.76, which is so faint that it can only seen in large amateur or bigger telescopes.

This object is more massive than a planet (55 ± 15 MJ), but less massive than a star (0.052 MSun). The radius of the brown dwarf is about that of Jupiter (or one-tenth that of the Sun). Its surface temperature is 2600 ± 150 K, which is about half that of the Sun. Its luminosity is 0.1% that of the Sun, meaning it takes six months for Teide 1 to emit the amount of radiation emitted by the Sun in four hours. Its age is only 120 million years compared to the Sun's age of 4.6 billion years. This brown dwarf is hot enough to fuse lithium in its core, but not hot enough to fuse hydrogen like the Sun.>>
Tszabeau wrote:
Speaking of brown dwarfs, does anyone know if they only form in orbit around fully developed stars or can they form on their own?
Most known brown dwarfs are in planetary like orbits around other stars.

It is not unreasonable to speculate that most of those that don't orbit stars (including Teide 1 above) escaped from larger shorter lived stars that have lost/ejected over half their mass (thereby making orbital velocity > escape velocity).
http://en.wikipedia.org/wiki/Gliese_229 wrote:

<<Gliese 229 (also written as Gl 229 or GJ 229) is a red dwarf star about 19 light years away in the constellation Lepus. It has 58% of the mass of the Sun, 69% of the Sun's radius, and a very low projected rotation velocity of 1 km/s (vs. ~2 km/s for the Sun) at the stellar equator. The star is known to be a low activity flare star, which means it undergoes random increases in luminosity because of magnetic activity at the surface. The spectrum shows emission lines of calcium in the H and K bands. The emission of X-rays has been detected from the corona of this star. These may be caused by magnetic loops interacting with the gas of the star's outer atmosphere. No large-scale star spot activity has been detected.

In 1994 a substellar companion was imaged and it was confirmed in 1995. Gliese 229B is a brown dwarf orbiting the star; although it is too small to sustain hydrogen-burning nuclear fusion, with a mass of 20 to 50 times that of Jupiter (0.02 to 0.05 solar masses) it is still too massive to be a planet. Gliese 229B was the first confirmed substellar-mass object. This object has a surface temperature of 950 K.>>
Tszabeau wrote:
Do they, in-turn have orbiting planets?
http://en.wikipedia.org/wiki/2M1207 wrote: <<2M1207, 2M1207A or 2MASS J12073346-3932539 is a brown dwarf located in the constellation Centaurus; a companion object, 2M1207b, may be the first extrasolar planetary mass companion to be directly imaged, and is the first discovered orbiting a brown dwarf.

2M1207 was discovered during the course of the 2MASS infrared sky survey: hence the "2M" in its name, followed by its celestial coordinates. With a fairly early (for a brown dwarf) spectral type of M8, it is very young, and probably a member of the TW Hydrae association. Its estimated mass is around 25 Jupiter masses. The companion, 2M1207b, is estimated to have a mass of 3–10 Jupiter masses. Still glowing red hot, it will shrink to a size slightly smaller than Jupiter as it cools over the next few billion years.

An initial photometric estimate for the distance to 2M1207 was 70 parsecs. In December 2005, American astronomer Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method. The new distance gives a fainter luminosity for 2M1207. Recent trigonometric parallax results have confirmed this moving cluster distance, leading to a distance estimate of 53 ± 1 parsec or 172 ± 3 light years.

Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust which accrete onto the brown dwarf. 2M1207 was first suspected to have such a disk because of its broad Hα line. This was later confirmed by ultraviolet spectroscopy. The existence of a dust disk has also been confirmed by infrared observations. In general, accretion from disks is known to produce fast-moving jets, perpendicular to the disk, of ejected material. This has also been observed for 2M1207; an April 2007 paper in the Astrophysical Journal reports that this brown dwarf is spouting jets of material from its poles. The jets, which extend around 109 kilometers into space, were discovered using the Very Large Telescope (VLT) at the European Southern Observatory. Material in the jets streams into space at a few kilometers per second.>>
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by jimbo48 » Mon Sep 03, 2012 3:22 pm

Does the Pleiades cluster really contain over 3,000 stars???
The picture surely does not indicate this. Does someone have a citation for this?

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by neufer » Mon Sep 03, 2012 4:09 pm

jimbo48 wrote:
Does the Pleiades cluster really contain over 3,000 stars???

The picture surely does not indicate this.
http://en.wikipedia.org/wiki/Pleiades wrote:
<<The Pleiades, or Seven Sisters (Messier object 45 or M45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. The cluster core radius is about 8 light years and tidal radius is about 43 light years. The cluster contains over 1,000 statistically confirmed members, although this figure excludes unresolved binary stars. It is dominated by young, hot blue stars, up to 14 of which can be seen with the naked eye depending on local observing conditions. The arrangement of the brightest stars is somewhat similar to Ursa Major and Ursa Minor. The total mass contained in the cluster is estimated to be about 800 solar masses.

The cluster contains many brown dwarfs, which are objects with less than about 8% of the Sun's mass, not heavy enough for nuclear fusion reactions to start in their cores and become proper stars. They may constitute up to 25% of the total population of the cluster, although they contribute less than 2% of the total mass. Astronomers have made great efforts to find and analyse brown dwarfs in the Pleiades and other young clusters, because they are still relatively bright and observable, while brown dwarfs in older clusters have faded and are much more difficult to study.>>
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Psnarf » Mon Sep 03, 2012 4:45 pm

I don't recall ever noticing the reflection nebulae before. The long exposure also brings out some of the brown dwarfs.

Galileo cheated, he used a telescope.
http://psnarf.org/Galileo/Galileo.Plead ... us.p39.jpg [I don't know who defaced this page with a pencil.]
http://psnarf.org/Galileo/Galileo.Plead ... us.p40.jpg

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Ann » Mon Sep 03, 2012 5:17 pm

Psnarf wrote:

The long exposure also brings out some of the brown dwarfs.
No. From a distance of 400 light-years, brown dwarfs are much, much too faint to show up in a visible-light photograph like this one. In fact, a brown dwarf would be much too faint to show up in a visible-light picture from a distance of 4 light-years, similar to the distance to Alpha Centauri. The faint-looking yellowish points of light in the Pleiades cluster are regular hydrogen-fusing stars, far, far brighter than brown dwarfs, although much, much fainter than the bright B-type stars that make up the well-known outline of the cluster.

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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Beyond » Mon Sep 03, 2012 5:21 pm

ta152h0 wrote:wow !! Just struck me tonight the ancient egyptians were great capitalists. Cheaper to build three pyramids than to build 7 !
Now wait just a pointy pyramidal minute there, consumer of cold ones, 'capitalists' know that it's cheaper to mass produce, rather than only produce a few. IF that were not the case, you wouldn't be able to afford a case of the cold ones :!: :mrgreen:
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Beyond » Mon Sep 03, 2012 5:27 pm

Ann wrote:
Boomer12k wrote:Ann must be in Blue Heaven... :D

Just an AWESOME Picture...THANKS.


:---[===]*
I am!!! Image

The Pleiades is the loveliest, visually bluest, best-recognized and most beloved star cluster in the sky. Nuff said!

Ann
Ann, it just struck me that the blue smilie would make a good avatar for you, especially if you could make the top and bottom white spots slightly blue, and put them in the eyes of the smilie.
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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by Boomer12k » Mon Sep 03, 2012 10:28 pm

If you look between Maia and Alcyone...closer to Maia....and heading towards Merope...IF you look at the wispy outlines JUST RIGHT....you can see the appearance of an IMPERIAL WALKER!!!! :shock:
By Maia, just to HER RIGHT...our left...is the top of the cabin, and down towards Merope are the long legs....


But it is probably just me.... :D


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Re: APOD: M45: The Pleiades Star Cluster (2012 Sep 03)

Post by DavidLeodis » Tue Sep 04, 2012 12:42 pm

I have no problem with repeating an APOD image. When I saw this one I knew it had been used before but on doing a search I was surprised that it was apparently last used much longer ago than I would have guessed, namely January 9 2006. Wow, time does fly at times! In view of the editors note to the APOD of September 3 2012 I was amused that when this photo was used for the APOD of December 27 2003 this was the editor's note "(Editors' note: The prominent diffraction spikes were added to the image for aesthetic reasons, produced by kite string donated by Rob Gendler's kids and placed over the telescope dew shield.)". :)