APOD: The Sombrero Galaxy from Hale (2013 Jul 15)

[APOD Robot]

The Sombrero Galaxy from Hale

Explanation: What's going on in the center of this spiral galaxy? Named the Sombrero Galaxy for its hat-like resemblance, M104 features a prominent dust lane and a bright halo of stars and globular clusters. Reasons for the Sombrero's hat-like appearance include an unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge visible in the above image from the 200-inch Hale Telescope. Close inspection of the central bulge shows many points of light that are actually globular clusters. M104's spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand. The very center of the Sombrero glows across the electromagnetic spectrum, and is thought to house a large black hole. Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo.

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[Dustin M.]

One of these days I wan't to see one of those galaxies approaching at some astronomical warp value. For now I settle for using my imagination but some day light speed limit, you will be superseded, if it means we bypass you in some round about way!

[Ann]

http://www.universetoday.com/94800/spit ... es-in-one/ wrote:

Spitzer Spots Two Galaxies in One

Click to view full size image

The Sombrero galaxy has a split personalty, according to recent observations by NASA’s Spitzer Space Telescope. Infrared imaging has revealed a hazy elliptical halo of stars enveloping a dual-structured inner disk; before this, the Sombrero galaxy was thought to be only disk-shaped.
...
“The Sombrero is more complex than previously thought,” said Dimitri Gadotti of the European Southern Observatory in Chile and lead author of the report. “The only way to understand all we know about this galaxy is to think of it as two galaxies, one inside the other.”

Although it might seem that the Sombrero is the result of a collision between two separate galaxies, that’s actually not thought to be the case. Such an event would have destroyed the disk structure that’s seen today; instead, it’s thought that the Sombrero accumulated a lot of extra gas billions of years ago when the Universe was populated with large clouds of gas and dust. The extra gas fell into orbit around the galaxy, eventually spinning into a flattened disk and forming new stars.
This is one of the first galaxies to be seen with such a dual structure — even though M104 has been known about since the mid-1700s.

The way I understand this, the Sombrero could be understood as an elliptical galaxy encircled by a spiral "belt". The Sombrero Galaxy acquired this "belt" by having gas gently falling into orbit around it, eventually becoming compressed enough to form stars.

Indeed, the Sombrero Galaxy is every so slightly reminiscent of gas giant planet Saturn and its regular, complex system of equatorial rings!

It is interesting to compare the Sombrero Galaxy with galaxies where a fully formed spiral is colliding with an elliptical galaxy. The two prime (moderately nearby) examples are Cen A, NGC 5128, and Perseus A, NGC 1275. In both cases, a spiral is clearly colliding with the elliptical, and it could be that Cen A and Perseus A will never acquire the "settled" look of M104. Interestingly, the warped disk of Cen A is revealed in this infrared ESO image.

Finally, let's look at this HST image of NGC 1316. Judging by appearances, NGC 1316 could be what a galaxy like Perseus A may look like in the future, when the shattered spiral is almost completely absorbed into the giant elliptical. Only tattered strands of dust remains of the hapless spiral galaxy.

Ann

[Boomer12k]

Awesome...the 200inch Hale...I have stood there....looking at it's awesomeness....now they are still making impressing photos!!!! Great Job!!!!

http://www.youtube.com/watch?v=z3ogtybbO9w

Short video about the Hale telescope, history, what they do now...interesting...

I tried to get a photo of M104 tonight, but even a 2 minute exposure doesn't come out to well...need to get the focus better....

:---[===] *

[Boomer12k]

Ann....The Spider and the Fly????

:---[===] *

[neufer]

The Sombrero Galaxy from Hale

Fifty million-year-old light from the Sombrero Galaxy can be seen
with a small telescope towards the constellation of Virgo.

Galileo's 1" refractor may have been fine for observing bright planets
but it took another order of magnitude in light gathering power with
Pierre Méchain's 3.5" refractor (170 years later) to observe the fuzzy Sombrero Galaxy.

Code: Select all

Object              Magnitude   Angular diameter
---------------------------------------------------------------
The Sombrero Galaxy    9.0      522″ x 210″
Galileo's Neptune      8.0        2.2″

http://en.wikipedia.org/wiki/Discovery_of_Neptune#Earlier_observations

<<The Sombrero Galaxy has an apparent magnitude of +9.0, making it easily visible with amateur telescopes. The Sombrero Galaxy was discovered in March 1767 by Pierre Méchain, who described the object in a May 1767 letter to J. Bernoulli that was later published in the Berliner Astronomisches Jahrbuch. Charles Messier made a hand-written note about this and five other objects (now collectively recognized as M104 – M109) to his personal list of objects now known as the Messier Catalogue, but it was not "officially" included until 1921. William Herschel independently discovered the object in 1784 and additionally noted the presence of a "dark stratum" in the galaxy's disc, what is now called a dust lane.>>

Re: Pierre Méchain: What scope(s)? Where? new [Re: BrooksObs]
#5796173 - 04/13/13 09:05 AM

In the instance of Messier and Mechain a quick examination revealed the following about the instruments used in some of their various discoveries and observations of comets. I would note that Messier far more often cited his telescopes than did Mechain.

C. Messier telescopic comet discoveries

• 1769 "using a 2-foot telescope..."
  1770 "using a 1-foot telescope..."
  1772 "observed with a small telescope and a 3.5-foot refractor..."
  1773 "...a 2-foot refractor..."
  1774 "observed with a Dollond 3.5-foot refractor"
  1779 "...using a 2-foot refractor and a Dolland 3.5-foot refractor"
  1780 "observed with a 3.5-foot refractor"
  1780 "found with a 3.5-foot refractor and further observed with a 2-foot refractor"
  1785 "...40" FL refractor"

P.Mechain telescopic comet discoveries

• 1780 "...observed with a 3.5" refractor"
  1781 "...using a 3.5-foot refractor"
  1781 "discovered with a 3.5" refractor"

Now cross referencing with some of Dollond's late 18th century instruments one finds some particularly interesting details. First off, such instruments were not commonly offered for astronomical purposes with only a single fixed magnification, as was suggested earlier in this thread. Rather, they came with from 3 to 6 eyepieces. Dolland's refractors of 30" to 35" FL (3-foot) seem to have generally have been achromats of around 2" aperture. Those in the 45" to 60" range had objectives in the 3.5" class.

I found it particularly interestingly that Dolland (among others) also offered what were essentially RFT-type refractors! Reference to several from Messier's and Mechain's era that were 2" to 2.5" aperture with FL of 17" to 20" is made. There were even some that were so small that they were about the overall equivalent of modern 7x35 monoculars!

Messier's 7.5", narrow field, Gregorian reflector is never mentioned as being used for his comet sweeping/discoveries and as I indicated upstream, was normally employed in better defining the RA and Dec. of his newly found "comet-like objects" for his catalog.

It is obvious that both Messier and Mechain were well aware of exit pupil size advantages and the need for short FL, low power telescopes for comet hunting and their availability during the latter half of the 18th century.

A final point I would like to offer is in regard to these two gentleman observing from Paris. While the city's air was certainly polluted by smoke in this period, the skies would still have been dramatically darker than probably 90% experience from our residences today. Even in the much more recent days of tungsten illumination skies over moderately large cities were decidedly better than today exists in their outermost suburbs! So, I'm sure Messier and Mechain enjoyed fairly good skies overall.>>

[RedFishBlueFish]

For, if flying saucers are as common as many believe, this should clearly be named the Flying Saucer galaxy.

It is almost as though flying saucers were invented long after the identification of this object. Of interest, the pilot who reported what came to be called 'flying saucers' actually was not referring to the shape of whatever it is that he saw - but do its apparent flight path.

How far away is this galaxy: APOD says 50, Wiki says 30, and a YouTube clip put out by the Chandra telescope people uses 25 million light years.

[JohnD]

I try not to fantasise about what APOD shows us. But an earlier InfraRed picture of the sombrero http://apod.nasa.gov/apod/ap050511.html shows that there is a complete ring of warm dust at the periphery of this galaxy, with little in the middle. I have to ask the cosmic mechanics - how would this compare with a disintegrated RingWorld the size of a galaxy?

In NIven's RingWorld only the shadow squares were damaged extensively. Iain M.Banks imagined smaller Orbitals and in "Consider Phlebas" destroyed one, by "grid-fire" (an imaginary force from between the multiverses - yes, I said fantasy). The dust from that rapidly dispersed as it was a small object, in comparison to a solar system. But would a Galatic RingWorld, reduced to dust, look like this?

John

[neufer]

How far away is this galaxy:
APOD says 50, Wiki says 30, and a YouTube clip put out by the Chandra telescope people
uses 25 million light years.

The 50 Mly probably comes from the average distance of the Virgo Cluster
of which the spiral M104 is a relatively near part.

<<At least two methods have been used to measure the distance to the Sombrero Galaxy.

The first method relies on comparing the measured fluxes from planetary nebulae in the Sombrero Galaxy to the known luminosities of planetary nebulae in the Milky Way. This method gave the distance to the Sombrero Galaxy as 29 ± 2 Mly.

The other method used is the surface brightness fluctuations method. This method uses the grainy appearance of the galaxy's bulge to estimate the distance to it. Nearby galaxy bulges will appear very grainy, while more distant bulges will appear smooth. Early measurements using this technique gave distances of 30.6 ± 1.3 Mly. Later, after some refinement of the technique, a distance of 32 ± 3 Mly was measured. This was even further refined in 2003 to be 29.6 ± 2.5 Mly.

The average distance measured through these two techniques is 29.3 ± 1.6 Mly.>>

[neufer]

Click to play embedded YouTube video.

I try not to fantasise about what APOD shows us. But an earlier InfraRed picture of the sombrero http://apod.nasa.gov/apod/ap050511.html shows that there is a complete ring of warm dust at the periphery of this galaxy, with little in the middle.

An earlier InfraRed picture of the sombrero http://apod.nasa.gov/apod/ap050511.html shows that there is a complete ring of cold dust at the periphery of this galaxy, with little cold dust in the middle.

[neufer]

Click to play embedded YouTube video.

[bystander]

http://www.universetoday.com/94800/spit ... es-in-one/ wrote:

Spitzer Spots Two Galaxies in One

http://asterisk.apod.com/viewtopic.php?t=28354

[JohnD]

Ok, Neufer, warm dust, cold dust, it "actually glows brightly in infrared light." http://apod.nasa.gov/apod/ap050511.html

Yes, it is sort of cold, >20K according to this paper: http://adsabs.harvard.edu/full/1995A%26A...303..673E which also offers several theories or mechanisms for the formation of the RingDust, that do not include a disintegrated Galactic RingWorld.

But I'd still like to ask. Banks descrobed the radial momentum of his Orbital as causing its residue to fly apart visibly. Would the same be true of the Galactic RingWorld if that were to disintegrate? Could we see it happening on this galactic scale and distance?

John

[BDanielMayfield]

That was a very helpful reference Bystander.

I wonder, how might the Milky Way look from a similar distance and viewing angle?

[JohnD]

Like this,



Or this, our Sister Andromeda, from a link provided by the indefatigable neufer!



John

[BDanielMayfield]

Thanks for that rapid response John.

A GALACTIC sized Ringworld??? The circumference of the Sombrero’s ring would be, what, about 380,000 lightyears. “The Ringworld” must have made a huge impression on you.

Bruce

P.S. I don't mean to imply that I'm laughting at you, but with you. I too thought that "The Ringworld" was a great story. But, haven't you heard, The Ringworld is unstable!

[Chris Peterson]

Galileo's 1" refractor may have been fine for observing bright planets but it took another order of magnitude in light gathering power with Pierre Méchain's 3.5" refractor (170 years later) to observe the fuzzy Sombrero Galaxy.

A 1" aperture telescope will present views at a 5X magnification as bright as those through any telescope, of any larger size. At 5x, the Sombrero appears larger than the Moon. It can certainly be observed (and quite easily) using a good quality 1" telescope (which Galileo's was not). It didn't require a larger telescope, it's simply the case that the first person to observe this object was using a larger one (as were virtually all observers after Galileo).

[neufer]

Galileo's 1" refractor may have been fine for observing bright planets but it took another order of magnitude in light gathering power with Pierre Méchain's 3.5" refractor (170 years later) to observe the fuzzy Sombrero Galaxy.

A 1" aperture telescope will present views at a 5X magnification as bright as those through any telescope, of any larger size. At 5x, the Sombrero appears larger than the Moon. It can certainly be observed (and quite easily) using a good quality 1" telescope (which Galileo's was not). It didn't require a larger telescope, it's simply the case that the first person to observe this object was using a larger one (as were virtually all observers after Galileo).

A night dilated pupil is about a third of an inch so make that 3X magnification.

Hence, a magnitude 9 star would become a magnitude 6.6 star.

Few people could see a magnitude 6.6 star using both eyes much less using one
(although Galileo apparently could see a magnitude 5.6 planet).

A fuzzy spread out magnitude 6.6 galaxy would be impossible to see, IMO.

(A magnitude 9 star with Pierre Méchain's 3.5" refractor would become a magnitude 4.9 star.)

[JohnD]

Quote, BDanielMayfield, "But, haven't you heard, The Ringworld is unstable!"

And that's why the Engineers installed the Rim Ramjets!

And if someone like Freeman Dyson can let down his supremely intellectual hair and indulge his imagination to think of Spheres, I can think of a Galactic RingWorld. Of course, I am thinking far too small, because as has been pointed out, a RingWorld is just a segment of a Sphere, and I should be imagining a Galactic Dyson Sphere!

But I think that has been done, and it would include an unbelievable volume of breathable air and such a low gradient gravity field, that beings could survive unsuited in permanent freefall, structures as big as planets could be built by Snartibartfast Inc., and you could get to Mars from Earth by flapping your wings and flying straight. Sort of Smoke Ring, without the navigational problem of "East takes you Out, Out takes you West, West takes you In, In takes you East. Port and Starboard bring you back."

John

[Chris Peterson]

A night dilated pupil is about a third of an inch so make that 3X magnification.

That's large, even for a child. At Galileo's age when he was observing, his dilated pupil size would be about 5mm. With a 25mm aperture, he could reach 5X magnification before his view started to dim.

Hence, a magnitude 9 star would become a magnitude 6.6 star.

We aren't discussing stars. Detectable star brightness scales approximately as the area of the aperture. But that is not the case for extended objects, which are never brighter through a telescope than they are to the naked eye, and for which the brightness does not depend on aperture (except above a magnification threshold).

A fuzzy spread out magnitude 6.6 galaxy would be impossible to see, IMO.

It isn't hard to see the Sombrero through small binoculars. You don't see much detail, but that it's a fuzzy oval is unmistakable.

[neufer]

A fuzzy spread out magnitude 6.6 galaxy would be impossible to see, IMO.

It isn't hard to see the Sombrero through small binoculars.
You don't see much detail, but that it's a fuzzy oval is unmistakable.

7 x 35 binoculars have almost 4 times the light gathering power of a 1" telescope
(especially a telescope with no anti-reflection coating).

In any event, the important point is that the APOD "suggests" that Galileo
was capable of observing M104 and we both agree that that is misleading.

[geckzilla]

You two are strangely and delightfully disagreeable when you are being agreeable.

[Anthony Barreiro]

This is a beautiful image!

Thanks Ann for the additional information about the Sombrero's odd shape and possible history.

The whole "small telescope" kerfuffle could have been avoided by linking to a picture of Pierre Mechain.

[Chris Peterson]

7 x 35 binoculars have almost 4 times the light gathering power of a 1" telescope
(especially a telescope with no anti-reflection coating).

Both have a 5mm exit pupil. The 35mm aperture collects twice as much light, but the higher power distributes it over twice the area of the retina, for no net increase in brightness. For a simple, two lens telescope like that used by Galileo, the improvement from AR coatings is minimal.

In any event, the important point is that the APOD "suggests" that Galileo
was capable of observing M104 and we both agree that that is misleading.

I don't agree. There's no reason at all to think that Galileo couldn't have observed M104 with one of his lower power telescopes (3X or 8X), and possibly even with the 20X version he used on the planets. Some of the telescopes he had at his disposal were capable of making M104 readily visible. It's simply a problem of finding it.

[neufer]

7 x 35 binoculars have almost 4 times the light gathering power of a 1" telescope
(especially a telescope with no anti-reflection coating).

Both have a 5mm exit pupil.

Why have a 5mm exit pupil on binoculars
if 5mm is the maximum eye dilation at night?

The 35mm aperture collects twice as much light,
but the higher power distributes it over twice the area of the retina, for no net increase in brightness.

Twice the retina area means twice the number of illuminated rods & cones for each eye.
(And, of course, binoculars mean twice that number of eyes.)

For a simple, two lens telescope like that used by Galileo, the improvement from AR coatings is minimal.

4 air-glass surfaces => Transmission = (0.96)⁴ = 85%

In any event, the important point is that the APOD "suggests" that Galileo
was capable of observing M104 and we both agree that that is misleading.

I don't agree. There's no reason at all to think that Galileo couldn't have observed M104 with one of his lower power telescopes (3X or 8X), and possibly even with the 20X version he used on the planets. Some of the telescopes he had at his disposal were capable of making M104 readily visible. It's simply a problem of finding it.

Galileo had telescopes with effective apertures larger than an inch?