APOD: The Annotated Galactic Center (2010 Aug 31)

[APOD Robot]

The Annotated Galactic Center

Explanation: The sky toward the center of our Galaxy is filled with a wide variety of celestial wonders, many of which are visible from a dark location with common binoculars. Constellations near the Galactic Center include Sagittarius, Libra, Scorpius, Scutum, and Ophiuchus. Nebulas include Messier objects M8, M16, M20, as well as the Pipe and Cat's Paw nebulas. Visible open star clusters include M6, M7, M21, M23, M24, and M25, while globular star cluster M22 is also visible. A hole in the dust toward the Galactic Center reveals a bright region filled with distant stars known as Baade's Window, which is visible between M7 and M8. Moving your cursor over the above image the will bring up an un-annotated version.

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[Joe Stieber]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

[neufer]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

<<Messier 28 (also known as M28 or NGC 6626) is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier in 1764. In the sky it is very close to the 3rd magnitude star Kaus Borealis. M28 is at a distance of about 18,000 to 19,000 light-years away from Earth. 18 RR Lyrae type variable stars have been observed in this cluster. In 1986, M28 became the first globular cluster where a millisecond pulsar was discovered (by the Lovell Telescope at Jodrell Bank Observatory).>>

http://antwrp.gsfc.nasa.gov/apod/ap011229.html

<<Lambda Sagittarii (λ Sgr) is a star within the constellation Sagittarius. The star marks the top of the Archer's bow, whence its traditional name Kaus Borealis. It also marks the top of the lid of the so-called "Teapot" asterism. In ancient Chinese astronomy, it is the 2nd of 6 stars in the Dipper or 'South Dipper' mansion of the Black Tortoise of the North. The name Kaus Borealis comes from the Arabic قوس qaws 'bow' and Latin boreālis 'northern'. To the south of it lie the other stars of the bow, Kaus Media and Kaus Australis.

Kaus Borealis is a spectral class K orange giant star. It is currently fusing helium into carbon and oxygen in its core. Kaus Borealis is 77 light years from us, with a mass 2.3 times that of the Sun. It is 52 times more luminous than the Sun and has a radius of some 11 Suns. Being near the ecliptic, Lambda Sgr is sometimes occulted by the Moon and , more rarely by a planet. The last planet to pass in front of it was Venus, on 19 November 1984. The previous occasion was on 5 December 1865, when it was occulted by the planet Mercury.>>

Teapot Rock viewed from the south – a few hundred yards east of Wyoming highway 259, just south of Teapot Creek, and about 19 miles north of Casper, Wyoming. The Teapot Dome oil fields are north of the rock to the right.

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<<Teapot Dome is an oil field on public land in the U.S. state of Wyoming, so named for Teapot Rock, an outcrop resembling a teapot south of the field. The Teapot Dome area and the United States Naval Oil Reserve covering most of the field are named for a nearby formation of eroded sandstone called Teapot Rock.

The oil fields at Teapot Dome and at Elk Hills & Buena Vista in California were located on public land reserved for emergency use by the U.S. Navy only when the regular oil supplies diminished. Many politicians and private oil interests opposed the limits placed on the oil fields, claiming that the reserves were unnecessary and that American oil companies could provide for the Navy. One of the public officials most avidly opposed to retaining the reserves was Republican Senator Albert B. Fall of New Mexico. A political alliance ensured his election to the Senate in 1912, and his political allies — who later made up the infamous "Ohio Gang" — convinced President Harding to appoint Fall as United States Secretary of the Interior in March 1921.

In 1922, Fall leased, without competitive bidding, the Teapot Dome fields to Harry F. Sinclair of Sinclair Oil, and the field at Elk Hills, California, to Edward L. Doheny. In 1922 and 1923, these transactions became the subject of a sensational U.S. Senate investigation conducted by Senator Thomas J. Walsh. Albert Fall was found guilty of bribery in 1929, fined $100,000 and sentenced to one year in prison, making him the first Presidential cabinet member to go to prison for his actions in office. Harry Sinclair was charged with contempt, fined $100,000, and received a short sentence for jury tampering.>>

[rstevenson]

I'd like just one more mark on that image: where's our galaxy's central black hole? (Behind the dust, I know. But which chunk of dust is it behind?)

Rob

[neufer]

I'd like just one more mark on that image: where's our galaxy's central black hole?
(Behind the dust, I know. But which chunk of dust is it behind?)

. http://antwrp.gsfc.nasa.gov/apod/ap011229.html

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<<The Galactic Center is the rotational center of the Milky Way galaxy. It is located at a distance of 8.33±0.35 kpc from the Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest. It is believed that there is a supermassive black hole at the Galactic Center of the Milky Way.

Because of interstellar dust along the line of sight, the Galactic Center cannot be studied at visible, ultraviolet or soft X-ray wavelengths. The available information about the Galactic Center comes from observations at gamma ray, hard X-ray, infrared, sub-millimetre and radio wavelengths.

Coordinates of the Galactic Center were first found by Harlow Shapley in his 1918 study of the distribution of the globular clusters. In the Equatorial coordinate system they are: RA 17h45m40.04s, Dec -29° 00' 28.1" (J2000 epoch).

The complex astronomical radio source Sagittarius A appears to be located almost exactly at the Galactic Center, and contains an intense compact radio source, Sagittarius A*, which coincides with a supermassive black hole at the center of our Galaxy. Accretion of gas onto the black hole, probably involving a disk around it, would release energy to power the radio source, itself much larger than the black hole. The latter is too small to see with present instruments.

A study in 2008 which linked radio telescopes in Hawaii, Arizona and California (Very Long Baseline Interferometry) measured the diameter of Sagittarius A* to be 0.3 AU. Scientists at the Max Planck Institute for Extraterrestrial Physics in Germany using Chilean telescopes have confirmed the existence of a super massive black hole at the galactic center. This black hole is of the order 4 million solar masses.

The central parsec around Sagittarius A* contains thousands of stars. Although most of them are old red main sequence stars, the Galactic Center is also rich in massive stars. More than 100 OB and Wolf-Rayet stars have been identified there so far. They seem to have all been formed in a single star formation event a few million years ago. The existence of these relatively young (though evolved) stars was a surprise to experts, who expected the tidal forces from the central black-hole to prevent their formation. This paradox of youth is even more remarkable for stars that are on very tight orbits around Sagittarius A*, such as S2. The scenarios invoked to explain this formation involve either star formation in a massive star cluster offset from the Galactic Center that would have migrated to its current location once formed, or star formation within a massive, compact gas accretion disk around the central black-hole. It is interesting to note that most of these 100 young, massive stars seem to be concentrated within one (according to the UCLA group) or two (according to the MPE group) disks, rather than randomly distributed within the central parsec. This observation however does not allow definite conclusions to be drawn at this point.

Star formation does not seem to be occurring currently at the Galactic center, although the Circumnuclear Disk of molecular gas that orbits the Galactic center at two parsecs seems a fairly favorable site for star formation. Work presented in 2002 by Antony Stark and Chris Martin mapping the gas density in a 400 light year region around the galactic center has revealed an accumulating ring with a mass several million times that of the Sun and near the critical density for star formation. They predict that in approximately 200 million years there will be an episode of starburst in the galactic center, with many stars forming rapidly and undergoing supernovae at a hundred times the current rate. The starburst may also be accompanied by the formation of galactic jets as matter falls into the central black hole. It is thought that the Milky Way undergoes a starburst of this sort every 500 million years.>>

[orin stepanek]

The movie is pretty neat; http://www.youtube.com/watch?v=36xZsgZ0oSo It shows stars orbiting the black hole!

[DaleW]

The "<" link for today's APOD goes to 29 Sept 2010, not 20 Sept 2010 as it should.

[rstevenson]

Thanks Art. Much better, though it makes we want X-ray glasses to see through all that dust.

Rob

[Chris Peterson]

Thanks Art. Much better, though it makes we want X-ray glasses to see through all that dust.

You're taking the wavelengths the wrong way. You want IR glasses, not x-ray. Fortunately, we have some very nice IR telescopes that peer through that dust very effectively- enough so to actually observe the orbits of stars around the central black hole.

[neufer]

Thanks Art. Much better, though it makes we want X-ray glasses to see through all that dust.

You're taking the wavelengths the wrong way. You want IR glasses, not x-ray. Fortunately, we have some very nice IR telescopes that peer through that dust very effectively- enough so to actually observe the orbits of stars around the central black hole.

NASA Image of the Day 2 February 2010

Hubble: NASA, ESA, and Q.D. Wang (University of Massachusetts); Spitzer: NASA, Jet Propulsion Laboratory, and S. Stolovy (Caltech) [url=http://upload.wikimedia.org/wikipedia/commons/1/15/An_Infrared_View_of_the_Galaxy.jpg][size=150]FULL RESOLUTION[/size][/url]

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<<This composite colour infra-red image of the centre of our Milky Way galaxy reveals a new population of massive stars and new details in complex structures in the hot ionized gas swirling around the central 300 light-years. This sweeping panorama is the sharpest infra-red picture ever made of the Galactic core and offers a laboratory for how massive stars form and influence their environment in the often violent nuclear regions of other galaxies. This view combines the sharp imaging of the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) with colour imagery from a previous Spitzer Space Telescope survey done with its Infra-red Astronomy Camera (IRAC). The Galactic core is obscured in visible light by intervening dust clouds, but infra-red light penetrates the dust. NICMOS shows a large number of these massive stars distributed throughout the region. A new finding is that astronomers now see that the massive stars are not confined to one of the three known clusters of massive stars in the Galactic Centre, known as the Central cluster, the Arches cluster, and the Quintuplet cluster. These three clusters are easily seen as tight concentrations of bright, massive stars in the NICMOS image. The distributed stars may have formed in isolation, or they may have originated in clusters that have been disrupted by strong gravitational tidal forces. The winds and radiation from these stars form the complex structures seen in the core, and in some cases, they may be triggering new generations of stars.>>

[rstevenson]

Thanks Art. I've got that one in my folder of interesting images, and a half-dozen others of the galactic center, from various instruments at various magnifications. But none of them indicated precisely where the monster was hiding, which is why I had to finally ask earlier today.

Rob

[Sam]

How possible would it be to "three-dimensionalize" this image? Or even better, the one linked-to below. Perhaps either viewable with red/blue glasses, or as a stereo image (to avoid color issues)? I know there's some uncertainty in the stellar distances, and there's more than a heck of a lot of stars to deal with, but considering that one of the frustrations associated with astronomy is that everything's so incomprehensibly far away, an image which shows some depth would increase in fascination with the square (or would it be the cube) of the surface area of the image. Being able to have a simple picture as a resource (however approximate) would make it so much easier to learn and appreciate the form of our galaxy, rather than constantly having to look up how many light-years a certain star or nebula or cluster is from us.

One of the things I like about Stéphane Guisard's image:
http://apod.nasa.gov/apod/ap090925.html
is that the number of stars in front of the different dust clouds seems to give an indication of their distance: thus the Pipe Nebula, with hardly any stars between it and us, appears closer than the dark clouds to the left of it which have smatterings of star fields that seem to fade the intensity of their [the dust clouds'] color. It's exactly like how we can perceive distances on Earth based on the amount of intervening atmosphere: a (small) faded green tree is perceived as further from us than a (large) darker green tree. (On the other hand, M4, 7200 l.y., looks almost closer than Antares, 600 l.y.) Apollo astronauts on the Moon, however, were frequently unsure of their distance perception because the Moon has no atmosphere, and no trees--only rocks, which could be of any size. Now obviously the things in this [Milky Way] image are even more unfamiliar than anything to be seen on Earth or Moon, so my instinctual labeling of objects as "foreground" or "background" could be completely off base--which is exactly why we need a 3D version! How far is the galactic center (27000 +/-1000 l.y.) in relation to the size of the picture frame? Is it just beyond those dust clouds, maybe a spiral arm or two more? Or is it so far, and the things visible here so relatively close, that a 3D image would appear virtually indistinguishable from a 2D image? I guess all this would depend on the amount of separation between "eyes"--would "Milky Way in Springtime" (left eye) combined with "Fall Milky Way" (right eye) be enough?

I'm eagerly awaiting the production of this new image, so if you must dash my hopes with reasons why it couldn't be, please do so gently.

[Ann]

This illustration of the Milky Way gives you an idea of the size of the Sun's orbit around the galactic centre.



As for the distances of the nebulae, reddening gives youu a clue. Look at M16, the Eagle Nebula, M17, Omega Nebula, and M8, the Lagoon. They are all relatively unreddened and look pink and white. The distances to them are around 5,000 light years, but be warned that I haven't looked them up.

But now look at NGC 6357 and NGC 6334, the Cat's Paw Nebula. They are both noticably reddened. They look all red, hardly pink and not at all white. That is because they are farther away, and they are severely reddened. The pink and white nebulae in the image are in front of any major lane, but NGC 6357 and NGC 6334 are behind a lot of dust.

Ann

[Sam]

Yes but I want to see what this looks like from OUR angle - i.e., stars popping out at me

[Chris Peterson]

Yes but I want to see what this looks like from OUR angle - i.e., stars popping out at me :D

Most of the non-stellar objects have distances established, with at least moderate accuracy. Most of the stars don't. So there's no way to really make an image like this truly 3D. What modern planetarium software intended to simulate galactic tours does is to use the distances for some objects, and then to simply synthesize most of the stars according to a density rule. So what you see isn't completely true to reality, but you get a good idea of the 3D structure in a generic sense.

[Joe Stieber]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

The mismarked label has been corrected!

[neufer]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

The mismarked label has been corrected!

[img3="Operation: The Simpsons "Talking Homer" Edition."]http://ancientearthentertainment.com/st ... ration.jpg[/img3]

All the fun of classic Operation with
Homer Simpson as the talking patient!

<<Poor Homer is sick, better operate quick! Use forceps to remove his comical ailments: Bowler's Thumb, Foot in Mouth, Rubber Neck, Trick Knee and many more! Even better...Homer talks! Set off the buzzer and you'll get an earful! 4 "AAA" batteries required (not included).

Ages 6 and up / 1 or More Players.>>

[Beyond]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

The mismarked label has been corrected!

[img3="Operation: The Simpsons "Talking Homer" Edition."]http://ancientearthentertainment.com/st ... ration.jpg[/img3]

All the fun of classic Operation with
Homer Simpson as the talking patient!

<<Poor Homer is sick, better operate quick! Use forceps to remove his comical ailments: Bowler's Thumb, Foot in Mouth, Rubber Neck, Trick Knee and many more! Even better...Homer talks! Set off the buzzer and you'll get an earful! 4 "AAA" batteries required (not included).

Ages 6 and up / 1 or More Players.>>

I don't see a place for "foot-in-mouth." Could it be that it is not annotated or perhaps covered by lots of space dust because of non-use?

[neufer]

I don't see a place for "foot-in-mouth." Could it be that it is not annotated or perhaps covered by lots of space dust because of non-use?

<<In "Hungry are the Damned" the Simpsons are in their backyard having a barbecue when they are abducted by extraterrestrial life forms (specifically Kang and Kodos). They explain that they are taking the Simpsons to their homeworld. En route they present the family with enormous amounts of food and watch eagerly as they gorge themselves. Suspicious of the alien's intentions, Lisa sneaks into the kitchen and finds a book titled

How To Cook Humans.

She takes the book and shows it to the aliens, who explain to her that part of the title was obscured by space dust, which they then blow away to reveal the title

How To Cook For Humans.

Lisa, skeptical at this, blows off more space dust, revealing the title to be

How To Cook Forty Humans.

The aliens blow off the last of the space dust, finally revealing the real title

How To Cook For Forty Humans.

Enraged at Lisa's distrust, they return the Simpsons to Earth, explaining that
Lisa ruined the family's chance at paradise on the aliens' home planet.>>

[DavidLeodis]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

The mismarked label has been corrected!

I'm very confused (as mostly usual!) as the line pointing to M28 in the APOD as it currently is does not point to what it does in the annotated version in Jaime Fernandez's website. I would be grateful if someone could verify which is correctly pointing to M28. Is it as in the APOD or is it as in Jaime's website Thanks.

[DavidLeodis]

Note that M28 is mismarked. The line from the label is actually leading to Lambda Sagittarii (Kaus Borealis, the star marking the northern tip of the archer's bow, or alternatively, the apex of the Teapot's lid). M28 is the next brightish object to the right of Lambda.

The mismarked label has been corrected!

I'm very confused (as mostly usual!) as the line pointing to M28 in the APOD as it currently is does not point to what it does in the annotated version in Jaime Fernandez's website. I would be grateful if someone could verify which is correctly pointing to M28. Is it as in the APOD or is it as in Jaime's website Thanks.

The APOD currently now shows the annotated version that is in Jaime's website! Unless it has been changed in the last few minutes I'm totally baffled! I wonder if when I was online a few minutes back that when I thought I was seeing the current version of the APOD I was actually seeing the APOD version that I saved yesterday as that was still in my 'cache' (I hope that is the right term).

[DavidLeodis]

The APOD is now showing the original version! I give in! I don't know what I am doing but I clearly seem to be doing something wrong! I shall now keep quiet on this thread so as not to bore you all anymore. Very but still (just about) ing.

[bystander]

The APOD currently now shows the annotated version that is in Jaime's website! Unless it has been changed in the last few minutes I'm totally baffled! I wonder if when I was online a few minutes back that when I thought I was seeing the current version of the APOD I was actually seeing the APOD version that I saved yesterday as that was still in my 'cache' (I hope that is the right term).

I suspect what you were seeing was a cached version which now has been refreshed. I had to do a manual refresh to see the current version.

[Beyond]

How to Cook for 40 People

It's a good thing that the Simpson's did not find the "annotated" book -- How to Serve Man or the Simpsons would have been going from the Flyer to the Flying pan instead