APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

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APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby APOD Robot » Sun Mar 25, 2012 4:06 am

Image Barred Spiral Galaxy NGC 1300

Explanation: Big, beautiful, barred spiral galaxy NGC 1300 lies some 70 million light-years away on the banks of the constellation Eridanus. This Hubble Space Telescope composite view of the gorgeous island universe is one of the largest Hubble images ever made of a complete galaxy. NGC 1300 spans over 100,000 light-years and the Hubble image reveals striking details of the galaxy's dominant central bar and majestic spiral arms. In fact, on close inspection the nucleus of this classic barred spiral itself shows a remarkable region of spiral structure about 3,000 light-years across. Unlike other spiral galaxies, including our own Milky Way, NGC 1300 is not presently known to have a massive central black hole.

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Sandstone » Sun Mar 25, 2012 4:25 am

Absolutely stunning image!

Clicking through the links embedded in the caption, came to the Hubblesite.org website, where this image was posted Jan 10, 2005.

It's an interesting reflection to see how far we've come with computing power and digital imagery since then, as the "full resolution" version (the same one posted on APOD when you click the main image, 6637 x 3787 pixels), came with this warning (in 2005):

"FILE DOWNLOAD WARNING: You are attempting to access an image with an extremely high resolution. Please read on before downloading any of these images or return to other image format options."

then goes on to say

"If you still want to use this format, we strongly recommend that you download our "high resolution images" rather than our "full resolution images." The "high resolution images" provide a more manageable file size for most computers. Very few computers will be able to handle the "full resolution images..."

They do offer, among other alternatives, a "Large" format version, 800 x 456 pixels, and a "Small" format at 200 x 200 pixels.

Have things really changed that much in 7 years?

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby ritwik » Sun Mar 25, 2012 7:46 am

mystic power of spiral
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Click to play embedded YouTube video.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby orin stepanek » Sun Mar 25, 2012 12:33 pm

No massive black hole; but this galaxy has a massive bar! 8-)
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby moonstruck » Sun Mar 25, 2012 1:39 pm

Another amazing Hubble image. Does anyone know how they aim the Hubble in all different directions to zero in on an image? Is someone on earth looking at a monitor and say ahh there's something "click"? Or does it automatically know how to find things by the light the images are transmitting. Or what? :?

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby neufer » Sun Mar 25, 2012 2:44 pm

orin stepanek wrote:
No massive black hole; but this galaxy has a massive bar! 8-)

No KNOWN massive black hole.

The strong central vortex may be indicative of a massive central black hole surrounded by so much local angular momentum that there is nothing for it to eat and thereby give itself away by "burping."
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Sun Mar 25, 2012 2:51 pm

Sandstone wrote:Clicking through the links embedded in the caption, came to the Hubblesite.org website, where this image was posted Jan 10, 2005.

It's an interesting reflection to see how far we've come with computing power and digital imagery since then, as the "full resolution" version (the same one posted on APOD when you click the main image, 6637 x 3787 pixels), came with this warning (in 2005):

"FILE DOWNLOAD WARNING: You are attempting to access an image with an extremely high resolution. Please read on before downloading any of these images or return to other image format options."

then goes on to say

"If you still want to use this format, we strongly recommend that you download our "high resolution images" rather than our "full resolution images." The "high resolution images" provide a more manageable file size for most computers. Very few computers will be able to handle the "full resolution images..."

They do offer, among other alternatives, a "Large" format version, 800 x 456 pixels, and a "Small" format at 200 x 200 pixels.

Have things really changed that much in 7 years?

Yes, they have. And no, they have not <g>. There are many computer systems out there in current use that will choke trying to display a 25 megapixel image, and there are enough slow Internet connections in use to justify a similar warning on any image, even one posted for download in 2012.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Sun Mar 25, 2012 2:57 pm

moonstruck wrote:Another amazing Hubble image. Does anyone know how they aim the Hubble in all different directions to zero in on an image? Is someone on earth looking at a monitor and say ahh there's something "click"? Or does it automatically know how to find things by the light the images are transmitting. Or what? :?

The HST does nothing on its own. All the available imaging time is assigned to researchers via a complex process, and those researchers choose what they want to image. The HST is aimed at its chosen target using reaction wheels and magnetic torquers.

There is no realtime display on the ground of what the telescope is imaging. After an image is collected, the data is downloaded and can be viewed in its raw form, but isn't really useful until a complex calibration process is followed to remove systematic artifacts.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby neufer » Sun Mar 25, 2012 3:17 pm

Chris Peterson wrote:
moonstruck wrote:Another amazing Hubble image. Does anyone know how they aim the Hubble in all different directions to zero in on an image? Is someone on earth looking at a monitor and say ahh there's something "click"? Or does it automatically know how to find things by the light the images are transmitting. Or what? :?

The HST does nothing on its own. All the available imaging time is assigned to researchers via a complex process, and those researchers choose what they want to image. The HST is aimed at its chosen target using reaction wheels and magnetic torquers.

There is no realtime display on the ground of what the telescope is imaging. After an image is collected, the data is downloaded and can be viewed in its raw form, but isn't really useful until a complex calibration process is followed to remove systematic artifacts.

While Hubble can be pointed anywhere that is not too near the Sun, Earth or Moon, most all of the sky is visible at some time during Hubble's 96–97 minute orbit. However, (at a modest declination of -19.4°) NGC 1300 is not in one of Hubble's Continuous Viewing Zones.
http://www.stsci.edu/hst/proposing/docu ... view3.html wrote:
<<HST is in a relatively low orbit (~600 km above Earth), which imposes a number of constraints upon its observations. As seen from HST, most targets are occulted by the Earth for varying lengths of time during each 96-minute orbit. Targets lying in the orbital plane are occulted for the longest interval—about 44 minutes per orbit. These orbital occultations, analogous to the diurnal cycle for ground-based observing, impose the most serious constraint on HST observations. (Note that in practice the amount of available exposure time in an orbit is further limited by Earth-limb avoidance limits, the time required for guide star acquisitions or re-acquisitions, and instrument overheads.) The length of target occultation decreases with increasing angle from the spacecraft orbital plane. Targets lying within 24 degrees of the orbital poles are not geometrically occulted at any time during the HST orbit. This gives rise to so-called Continuous Viewing Zones (CVZs). The actual size of these zones is less than 24 degrees due to the fact that HST cannot observe close to the Earth limb. Since the orbital poles lie 28.5 degrees from the celestial poles, any target located in two declination bands near +/– 61.5 degrees may be in the CVZ at some time during the 56-day HST orbital precession cycle. Some regions in these declination bands can be unusable during the part of the year when the sun is too close to the region. The number and duration of CVZ passages depend on the telescope orbit and target position, and may differ significantly from previous cycles.>>
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby moonstruck » Sun Mar 25, 2012 3:47 pm

Thanks Art, it's not exactly point and shoot then. :wink: I'm glad that we have scientist and astronomers on earth smart enough to figure all this stuff out. I never could even find anything on purpose with a small telescope using alt and az settings. :?

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby JuanAustin » Sun Mar 25, 2012 3:55 pm

is there a correlation between the number of times a bar makes a rotation with number of years? i'm assuming the trailing arms would be longer and the spiral would be tighter?
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby moonstruck » Sun Mar 25, 2012 4:01 pm

And thanks, Chris.

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Sun Mar 25, 2012 4:07 pm

JuanAustin wrote:is there a correlation between the number of times a bar makes a rotation with number of years? i'm assuming the trailing arms would be longer and the spiral would be tighter?

Outer stars move somewhat slower than inner ones (although not as much as would be expected on first examination, due to the influence of dark matter). Spirals are some sort of wave phenomenon- they are not composed of the same group of stars over time. They move at a different speed than the stars themselves, and do not wind up over time.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby neufer » Sun Mar 25, 2012 4:19 pm

JuanAustin wrote:
is there a correlation between the number of times a bar makes a rotation with number of years? i'm assuming the trailing arms would be longer and the spiral would be tighter?

That depends on what model one uses and whether or not the model is accurate.
http://en.wikipedia.org/wiki/Spiral_galaxies wrote:
<<In April 2011 a presentation to the Royal Astronomical Society's April 2011 National Astronomy Meeting in Llandudno, Wales by postgraduate student Robert Grand, suggested that spiral arms do not rotate rigidly at a constant angular velocity about the galactic centre. This contradicts a 50 year old theory called Spiral Density Wave Theory (SDWT), which states that the spiral arm pattern we see is actually a wave pattern, that rotates independently of star and inter-stellar matter that follow the standard rotation curve of the galaxy. Stars that move faster than the arms can overtake them and move through them. Consequently, stars outside this radius move slower than the arm and fall behind. Rather than a long-lived rigidly rotating wave pattern found in SDWT, Grand's simulations suggested that the arms rotate with a pattern speed that decreases with radius, and that they are transient features, with some arms breaking up and new ones being formed over periods of 80 to 100 million years. Instead of stars rotating independently of the arm pattern, they co-rotate at every radius, as the arm pattern speed traces very well the rotation curve of matter. The destruction of the arms is due to a declining pattern speed, which means that the arms begin to wind up and so break to avoid the well-known Wind-Up problem. This pattern of arm formation and destruction has not been observed in real galaxies, mainly because this pattern would take tens of millions of years to observe from start to finish. As observers, we can only observe what is a relative "snapshot" of a galaxy's evolution, and since there are always new arms forming as older ones die, there is always a spiral pattern present. Therefore, a simple glance at a galaxy will not yield evidence either way. A real observational contribution will come from the Gaia satellite, due to be launched in the coming years.>>
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Ann » Sun Mar 25, 2012 4:40 pm

neufer wrote:
orin stepanek wrote:
No massive black hole; but this galaxy has a massive bar! 8-)

No KNOWN massive black hole.

The strong central vortex may be indicative of a massive central black hole surrounded by so much local angular momentum that there is nothing for it to eat and thereby give itself away by "burping."


I thought that the fact that the arms "curve back" so strongly and barely "leave the bar" also suggests that there is a lot of mass in the center of NGC 1300.

Image


Small galaxy NGC 1313 is also barred, but the short arms flare out almost without curving back toward the bar at all. I would guess that there is no massive black hole at the center of NGC 1313, although that is of course just a guess on my part.

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Sun Mar 25, 2012 4:56 pm

Ann wrote:I thought that the fact that the arms "curve back" so strongly and barely "leave the bar" also suggests that there is a lot of mass in the center of NGC 1300.

Maybe, but central supermassive black holes have a small mass compared with the stars in the central bulge of any galaxy. So a black hole is difficult or impossible to infer from dynamics. Basically, we only know they are there if they are active- that is, they are surrounded by enough nearby mass to be accreting it and producing high energy emissions. Certainly, that will not be the case for every galaxy.

Statistically, we should always assume that a spiral galaxy has a central black hole, even if one hasn't been observed. I don't know of any case where the lack of a black hole has been determined conclusively.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby ta152h0 » Sun Mar 25, 2012 7:59 pm

Not a painting. I see the spikes. Unless the painter is really big time good.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby ricardelico » Sun Mar 25, 2012 9:20 pm

Is a galaxy barred because of another galaxie's gravitational disruption of its original spiral form? Thank you for APoD.

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby neufer » Sun Mar 25, 2012 10:12 pm

ricardelico wrote:
Is a galaxy barred because of another galaxie's gravitational disruption of its original spiral form?

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Beyond » Sun Mar 25, 2012 11:42 pm

Now that's one Galaxy i think i could study for awhile :!: :yes: :chomp:
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Sun Mar 25, 2012 11:45 pm

ricardelico wrote:Is a galaxy barred because of another galaxie's gravitational disruption of its original spiral form? Thank you for APoD.

Probably not. It's more likely that the bar structure is a density wave system, similar to the spiral arms, and resulting from some sort of orbital resonance. Bars may exist in most or all spiral galaxies earlier in their evolution, eventually decaying away and leaving an unbarred spiral.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby neufer » Mon Mar 26, 2012 2:04 am

Chris Peterson wrote:
ricardelico wrote:
Is a galaxy barred because of another galaxie's gravitational disruption of its original spiral form?

Probably not. It's more likely that the bar structure is a density wave system, similar to the spiral arms, and resulting from some sort of orbital resonance. Bars may exist in most or all spiral galaxies earlier in their evolution, eventually decaying away and leaving an unbarred spiral.

Bars take time to form... and then to decay and reform.

Mature spiral galaxies spend 70% of their time in the bar.

(Overly mature SBm-type galaxies spend 70% of their time in the bar's bathroom.)
http://en.wikipedia.org/wiki/Barred_spiral_galaxy wrote:
<<Edwin Hubble classified these types of spiral galaxies as "SB" (spiral, barred) in his Hubble sequence, and arranged them into three sub-categories based on how open the arms of the spiral are. SBa types feature tightly bound arms, while SBc types are at the other extreme and have loosely bound arms. SBb-type galaxies lie in between. A fourth type, SBm, was subsequently created to describe somewhat irregular barred spirals, such as the Magellanic Cloud galaxies, which were once classified as irregular galaxies, but have since been found to contain barred spiral structures. Among other types in Hubble's classifications for the galaxies are: spiral galaxy, elliptical galaxy and irregular galaxy.

In 2005, observations by the Spitzer Space Telescope backed up previously collected evidence that suggested the Milky Way is a barred spiral galaxy. Observations by radio telescopes had for years suggested the Milky Way is barred, but Spitzer's vision in the infrared region of the spectrum has provided a more definite calculation.

Barred spiral galaxies are apparently predominant, with surveys showing that up to two-thirds of all spiral galaxies contain a bar. The current hypothesis is that the bar structure acts as a type of stellar nursery, fueling star birth at their centers. The bar is thought to act as a mechanism that channels gas inwards from the spiral arms through orbital resonance, in effect funneling the flow to create new stars. This process is also thought to explain why many barred spiral galaxies have active galactic nuclei, such as that seen in the Southern Pinwheel Galaxy.

The creation of the bar is generally thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting further out, which creates a self-perpetuating bar structure.

Bars are thought to be a temporary phenomenon in the life of spiral galaxies, the bar structure decaying over time, transforming the galaxy from a barred spiral to a "regular" spiral pattern. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Barred spiral galaxies with high mass accumulated in their center tend to have short, stubby bars. Since so many spiral galaxies have a bar structure, it is likely that it is a recurring phenomenon in spiral galaxy development. The oscillating evolutionary cycle from spiral galaxy to barred spiral galaxy is thought to take on the average about two billion years.

Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the "formative years" end. A team led by Kartik Sheth of the Spitzer Science Center at the California Institute of Technology in Pasadena discovered that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with nearly 70 percent of their modern counterparts.>>
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby StarCuriousAero » Tue Mar 27, 2012 11:41 pm

To Art or anyone else who can answer...

Has there been any effort to correlate a galaxy's location/trajectory (with respect to us and/or big bang origin) with its type/classification (and hence its "age" if you can call it that)? Is this maybe one of the goals of the galactic zoo project?

Is there a concentration of "young" barred-galaxies near our own? Or are different types of galaxies relatively evenly distributed?

Just trying to wrap my head around galaxy formation over time...

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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby Chris Peterson » Wed Mar 28, 2012 12:05 am

StarCuriousAero wrote:Has there been any effort to correlate a galaxy's location/trajectory (with respect to us and/or big bang origin) with its type/classification (and hence its "age" if you can call it that)?

There is no Big Bang origin. The age of a galaxy is related to its distance from us. Determining a trajectory is difficult, because we can only observe the radial velocity component; the transverse component is generally unknown.

Is there a concentration of "young" barred-galaxies near our own? Or are different types of galaxies relatively evenly distributed?

All galaxies formed fairly early in the Universe, and their appearance is partly due to the details of their formation, and partly due to their evolution and interactions with other galaxies. Galaxies exist in gravitationally bound clusters, but the types are well distributed.
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Re: APOD: Barred Spiral Galaxy NGC 1300 (2012 Mar 25)

Postby ta152h0 » Thu Mar 29, 2012 7:52 pm

In my mind, the Great Poobah in the Sky decided to create a soup for the myriads of earth dwellers to entertain themselves for eons to come. And made sure ice cold ones are made available.
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