APOD: Pleiades to Hyades (2011 Nov 17)

[APOD Robot]

Pleiades to Hyades

Explanation: This cosmic vista stretches almost 20 degrees across the gentle constellation Taurus. It begins at the Pleiades and ends at the Hyades, two of the best known star clusters in planet Earth's sky. At left, the lovely Pleiades star cluster is about 400 light-years away. In a familiar celestial scene, the cluster stars shine through dusty clouds that scatter blue starlight. At right, the V-shaped Hyades cluster looks more spread out compared to the compact Pleiades and lies much closer, 150 light-years distant. Of course, the Hyades cluster stars seem anchored by bright Aldebaran, a red giant star with a yellowish appearance. But Aldebaran actually lies only 65 light-years away, by chance along the line of sight to the Hyades cluster. Faint dust clouds found near the edge of the Taurus Molecular Cloud are also evident throughout the remarkable 12 panel mosaic. The wide field of view includes the youthful star T Tauri and Hind's variable nebula about four degrees left of Aldebaran on the sky.

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[mexhunter]

Congratulations Rogelio the image it's beautiful.
Greetings!
César

[Ann]

Oooh, Pleaides and Hyades by Rogelio Bernal Andreo!!!

Ann

[saturn2]

Pleiades cluster stars is more compact that Hyades.
Aldebaran red giant star is very bright.
It´s very giant star "only" 65 light-years away.

[orin stepanek]

Beatiful!

[Indigo_Sunrise]

Gorgeous image!

*madeitmydesktop*

[starstruck]

I always enjoy seeing The Pleiades, it's one of those constellations I regard as an old friend. When I was little, before I knew what it's proper name was, I always referred to it as 'the tennis racquet', that's just how it appeared to my young eyes . . don't shoot me but, if I'm honest, it will always be the tennis racquet to me! It's good to see it here in this excellent picture in the context of it's visual relation to The Hyades, but for me the orientation is slightly unusual, because when I look at this in the night sky I'm sure the tennis racquet would be higher and off to the right, sort of at the 2 o'clock position to The Hyades. But that's probably more to do with the time of the evening when I view it I expect.

[bactame]

The Hyades is not well shown in the photo, in fact the Pleiades is usually said to be on the back of the bull and this is not at all what one might guess with the image. Someone else might mumble about this to clarify but other than Aldebaran there is something unsaid in this APOD

[luigi]

The Hyades is not well shown in the photo, in fact the Pleiades is usually said to be on the back of the bull and this is not at all what one might guess with the image. Someone else might mumble about this to clarify but other than Aldebaran there is something unsaid in this APOD

There's nothing unsaid on this APOD. The view seems to be taken from the south hemisphere as it is exactly what I see from my location.

A really fantastic photo, I loved it!

[Psnarf]

I'm not that familiar with the Taurus asterism. It's been decades since I lived far from urban light pollution. I had to reference these sites to find my way.

http://www.nightskyinfo.com/archive/hya ... es_map.png
http://stars.astro.illinois.edu/sow/hyades-t.html
http://stars.astro.illinois.edu/sow/tau-t.html
http://deepskycolors.com/pics/astro/201 ... Hyades.jpg

Going back to the APOD, Elnath and Zeta, the horns of the bull, would be under Aldeberon off the bottom of the image?

For some Pleaiades fun, try to match Galileo's notebook to the APOD stars. Methinks there are more than Seven Sisters.
http://psnarf.org/Galileo/Galileo.Plead ... us.p39.jpg
http://psnarf.org/Galileo/Galileo.Plead ... us.p40.jpg

Perhaps someone could glue the two pages together? I think the drawing spans both pages.

[neufer]

.

[size=150][color=#0000FF]John Flamstead (Atlas celeste, Paris, 1776, Ed. J. Fortin); modern credit Linda Hall Library[/color][/size]

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[neufer]

<<T Tauri is a variable star in the constellation Taurus, the prototype of the T Tauri stars. It was discovered in October 1852 by John Russell Hind. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri; but it is actually 420 light years behind it and was not formed with the rest of them. Like all T Tauri stars, it is very young, being only a million years old. Its distance from Earth is about 580 light years, and its apparent magnitude varies unpredictably from about 9.3 to 14.

The T Tauri system consists of at least three stars, only one of which is visible at optical wavelengths; the other two shine in the infrared and one of them also emits radio waves. Through VLA radio observations, it was found that the young star (the "T Tauri star" itself) dramatically changed its orbit after a close encounter with one of its companions and may have been ejected from the system.

Physically nearby is NGC 1555, a reflection nebula known as Hind's Nebula or Hind's Variable Nebula. It is illuminated by T Tauri, and thus also varies in brightness. The nebula NGC 1554 was likewise associated with T Tauri and was observed in 1868 by Otto Wilhelm von Struve, but soon disappeared or perhaps never existed, and is known as "Struve's Lost Nebula". A Herbig-Haro object also appears to be associated with Hind's nebula, or perhaps with the T Tauri system itself.

The T Tauri wind, so named because this young star is currently in this stage, is a phase of stellar development between the accretion of material from the slowing rotating material of a solar nebula and the ignition of the hydrogen that has agglomerated into the protostar. A protostar is the denser parts of a cloud core, typically with a mass around 104 solar masses in the form of gas and dust, that collapses under its own weight/gravity, and continues to attract matter.

The protostar, at first, only has about 1% of its final mass. But the envelope of the star continues to grow as infalling material is accreted. After a few million years, thermonuclear fusion begins in its core, then a strong stellar wind is produced which stops the infall of new mass. The protostar is now considered a young star since its mass is fixed, and its future evolution is now set.>>

[Wolf kotenberg]

Outstanding, really been a few great weeks in " out there imaging ". Today's scrambled word unearths a question I have had for a while and concerns sending a brave person to walk on Mars. Does this future person have access to interned in a world so far awy ( for humans ) ?

[Case]

A question concerning sending a brave person to walk on Mars. Does this future person have access to [internet] in a world so far [away]?

The distance to Mars varies, as the orbits of Earth and Mars around the Sun are not synchronized. It varies between ~55 million km (~34 million miles) and ~401 million km (~249 million miles). Light takes 3 minutes (closest) to 22 minutes (furthest) to travel that distance. Such a wait may not be crucial for reading APOD or a news site (retrieving such pages can be scheduled), but using a search engine would be frustrating.
Another thing is bandwidth. The Mars rover gets 256 kbps, about 1/100th of a low level broadband connection from a cable provider. You can image that a small community on Mars would have to use such a limited resource without frivolities like YouTube.
But we're not there yet, and the coming years may provide for improved interplanetary bandwidth technology once we get there.

[NoelC]

Rogelio makes looking this deeply into the universe look so easy, doesn't he?

What a rare and amazing view. Thank you for taking the time to capture it, Rogelio!

-Noel

[neptunium]

Rogelio makes looking this deeply into the universe look so easy, doesn't he?

What a rare and amazing view. Thank you for taking the time to capture it, Rogelio!

-Noel

Yes, he does! Thanks from me, too!

[islader2]

It is great to see your work==once more==as an APOD of such quality and relevance. Thanx.

[Ann]

The Hyades is not well shown in the photo

Rogelio's image is not primarily a portrait of the Hyades (and the Pleiades), but rather a portrait of the interstellar dust and gas in this part of the sky and the way it interacts with stars. Fascinatingly, a lot of gas and dust is seen in the direction of the Hyades, too, not just in direction of the Pleiades.

Is the Hyades interacting with interstellar dust? Possibly, but that is in no way certain. Just because we see dust in the direction of the Hyades doesn't mean that the dust is in the same place as the Hyades - the dust could be either in front of or behind the star cluster, just in the line of sight.

In any case, the Hyades is a relatively old cluster, considerably older than the Pleiades. The Pleiades is lighting up a dust cloud that it has just accidentally "blundered into". Unless the Hyades has done the same thing, it will not be involved with a lot of dust.

Interestingly, however, there may be some dust close to the Hyades. Is there a reason why the stars aren't lighting it up? Yes, if there is indeed dust close to the Hyades, there may be two reasons why we don't see a reflection nebula - at least I've never seen a reflection nebula around the Hyades in any image prior to this one! First, the dust may be thin and spread out, not concentrated. Anything that is thin and spread out will not be good at lighting up anything. And second, the stars can't be too good at emitting the kind of light that is good at creating a reflection nebula. The latter is actually the case. The Hyades are, compared with the Pleiades, yellower and fainter. But yellow and faint isn't very good if you want to make a reflection nebula. The starlight that is most easily reflected is bright and blue, like the light from the bright B-type Pleiades.

But take a look! Isn't there a hint of nebulosity around Theta 1 and Theta 2 Tauri, the bluish and yellowish "double star" at 11 o'clock from Aldebaran?

It is fascinating to see the "dustscape" between the two famous clusters of Taurus. I don't know if I'm imagining things, but I think I see a hint of yellow nebulosity around Aldebaran. Could that be a yellow reflection nebula?

Again, thank you for showing us a unique view of the Pleiades and Hyades and their surroundings, Rogelio!

Ann

[Sam]

...gentle constellation Taurus.

Click to play embedded YouTube video.

[Jim G.]

Okay, I'm in the Northern Hemispere, outside Boston. The picture is reverse of what I see, right? Pleiades is to the right of Hyades. Looking from left to right, I see Orion, then Hyades and then Pleiades. Please let me know if this is not right. Thanks, I enjoy all the APOD's!!!

[rstevenson]

Hi Jim,

I'm a little further north, in Dartmouth, NS. My astronomy software tells me that right now (about 9pm your time on Nov. 22, 2011) if I could see the stars at all, the Hyades and Pleiades would both be just a little south of East, with the Pleiades almost directly above the Hyades and Orion well below. The three of them stretch from about 20° up from the horizon (Orion) to almost 60° up. In the sky the Pleiades looks a lot like a question mark or some similar shape (perhaps on its side, depending on time of year.) The Hyades includes the obviously orange star Aldebaran. With the naked eye it's not easy to see the Hyades, but a 7x40 pair of binocs helps a lot.

HTH

Rob

[Jim G.]

Thanks Rob, now it makes sense. But same here, will have to wait a couple days before we can see the stars again.

[starman]

Just a few comments: that "104 solar masses" in the nice article about T Tau should (of course) be 10-to-the-power-four (10,000) solar masses! I'm sure that the reflection nebula around the Pleiades is a remnant of the parent gas cloud from which they formed. The Pleiades is a young cluster so some of the material is still there. The gas clouds aren't involved with the Hyades - it's just a line of sight effect. There are lots more of them North of Aldebaran and in fact they extend right up into Auriga, especially near iota Aur, where there's a huge starforming region containing several young variable stars. An example is AB Aurigae which is visible at all times with binoculars. It is actually a wide double star, and the companion is another T Tauri type star, SU Aurigae (you'll need a small telescope for that one). Very close again is a third irregular variable, GM Aurigae, which is fainter still. A very active part of the sky. Lovely pic!

[Chris Peterson]

I'm sure that the reflection nebula around the Pleiades is a remnant of the parent gas cloud from which they formed. The Pleiades is a young cluster so some of the material is still there.

I believe it has been conclusively determined that the reflection nebula around the Pleiades is unrelated to the material from which those stars formed. While the stars are considered young at around 100 million years, that is an order of magnitude or more longer than local dust and gases could persist. The nebula is just a clump in the interstellar medium that the stars happen to be passing through at the moment.