APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

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Expand view Topic review: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

Re: We are red giant stuff

by neufer » Fri Dec 13, 2019 8:12 pm

Ann wrote: Fri Dec 13, 2019 6:57 pm
Wow. Who'd a thunk that Palladium was so important?
  • Palladium is only important in SOHO:
https://en.wikipedia.org/wiki/Palladium wrote:
<<William Hyde Wollaston noted the discovery of a new noble metal in July 1802 in his lab book and named it palladium after the asteroid 2 Pallas in August of the same year. Wollaston purified a quantity of the material and offered it, without naming the discoverer, in a small shop in SOHO in April 1803.>>
https://en.wikipedia.org/wiki/London_Palladium wrote:
<<The London Palladium is a 2,286-seat theatre located in the famous area of SOHO. Walter Gibbons, an early moving-pictures manager, built the Palladium in 1910 to compete with Sir Edward Moss's London Hippodrome and Sir Oswald Stoll's London Coliseum.
https://en.wikipedia.org/wiki/Soho wrote:
<<The name SOHO first appears in the 17th century. The name may possibly derive from a former hunting cry. A significant event in the history of epidemiology and public health was Dr. John Snow's study of an 1854 outbreak of cholera in Soho. Snow mapped the addresses of the sick, and noted that they were mostly people whose nearest access to water was the Broad Street public pump. He persuaded the authorities to remove the handle of the pump, thus preventing any more of the infected water from being collected. The spring below the pump was later found to have been contaminated with sewage. This is an early example of epidemiology, public health medicine and the application of science—the germ theory of disease—in a real-life crisis.>>

Re: We are red giant stuff

by Ann » Fri Dec 13, 2019 6:57 pm

neufer wrote: Fri Dec 13, 2019 6:11 pm
https://ethz.ch/en/news-and-events/eth-news/news/2019/12/stardust-from-red-giants.html wrote:
Stardust from red giants
ETH Zurich News | 09.12.2019
By: Barbara Vonarburg (public outreach)

<<Some of the Earth's building material was stardust from red giants, researchers from ETH Zurich have established. They can also explain why the Earth contains more of this stardust than the asteroids or the planet Mars, which are farther from the sun.

Around 4.5 billion years ago, an interstellar molecular cloud collapsed. At its centre, the Sun was formed; around that, a disc of gas and dust appeared, out of which the earth and the other planets would form. This thoroughly mixed interstellar material included exotic grains of dust: “Stardust that had formed around other suns,” explains Maria Schönbächler, a professor at the Institute of Geochemistry and Petrology at ETH Zurich. These dust grains only made up a small percentage of the entire dust mass and were distributed unevenly throughout the disc. “The stardust was like salt and pepper,” the geochemist says. As the planets formed, each one ended up with its own mix.

Thanks to extremely precise measurement techniques, researchers are nowadays able to detect the stardust that was present at the birth of our solar system. They examine specific chemical elements and measure the abundance of different isotopes – the different atomic flavours of a given element, which all share the same number of protons in their nuclei but vary in the number of neutrons. “The variable proportions of these isotopes act like a fingerprint,” Schönbächler says: “Stardust has really extreme, unique fingerprints – and because it was spread unevenly through the protoplanetary disc, each planet and each asteroid got its own fingerprint when it was formed.”

Over the past ten years, researchers studying rocks from the Earth and meteorites have been able to demonstrate these so-​called isotopic anomalies for more and more elements. Schönbächler and her group have been looking at meteorites that were originally part of asteroid cores that were destroyed a long time ago, with a focus on the element palladium.
Palladium. Photo: Jorchr.
Palladium. Photo: Annette.




















Wow. Who'd a thunk that Palladium was so important?

Ann

We are red giant stuff

by neufer » Fri Dec 13, 2019 6:11 pm

https://ethz.ch/en/news-and-events/eth-news/news/2019/12/stardust-from-red-giants.html wrote:
Stardust from red giants
ETH Zurich News | 09.12.2019
By: Barbara Vonarburg (public outreach)

<<Some of the Earth's building material was stardust from red giants, researchers from ETH Zurich have established. They can also explain why the Earth contains more of this stardust than the asteroids or the planet Mars, which are farther from the sun.

Around 4.5 billion years ago, an interstellar molecular cloud collapsed. At its centre, the Sun was formed; around that, a disc of gas and dust appeared, out of which the earth and the other planets would form. This thoroughly mixed interstellar material included exotic grains of dust: “Stardust that had formed around other suns,” explains Maria Schönbächler, a professor at the Institute of Geochemistry and Petrology at ETH Zurich. These dust grains only made up a small percentage of the entire dust mass and were distributed unevenly throughout the disc. “The stardust was like salt and pepper,” the geochemist says. As the planets formed, each one ended up with its own mix.

Thanks to extremely precise measurement techniques, researchers are nowadays able to detect the stardust that was present at the birth of our solar system. They examine specific chemical elements and measure the abundance of different isotopes – the different atomic flavours of a given element, which all share the same number of protons in their nuclei but vary in the number of neutrons. “The variable proportions of these isotopes act like a fingerprint,” Schönbächler says: “Stardust has really extreme, unique fingerprints – and because it was spread unevenly through the protoplanetary disc, each planet and each asteroid got its own fingerprint when it was formed.”

Over the past ten years, researchers studying rocks from the Earth and meteorites have been able to demonstrate these so-​called isotopic anomalies for more and more elements. Schönbächler and her group have been looking at meteorites that were originally part of asteroid cores that were destroyed a long time ago, with a focus on the element palladium.

Other teams had already investigated neighbouring elements in the periodic table, such as molybdenum and ruthenium, so Schönbächler’s team could predict what their palladium results would show. But their laboratory measurements did not confirm the predictions. “The meteorites contained far smaller palladium anomalies than expected,” says Mattias Ek, postdoc at the University of Bristol who made the isotope measurements during his doctoral research at ETH.

Now the researchers have come up with a new model to explain these results, as they report in the journal Nature Astronomy. They argue that stardust consisted mainly of material that was produced in red giant stars. These are aging stars that expand because they have exhausted the fuel in their core. Our sun, too, will become a red giant four or five billion years from now.
Scheme of stardust accumulation in our solar system. (Graphic from Ek et al, Nature Astronomy, 2019)

In these stars heavy elements such as molybdenum and palladium were produced by what is known at the slow neutron capture process. “Palladium is slightly more volatile than the other elements measured. As a result, less of it condensed into dust around these stars, and therefore there is less palladium from stardust in the meteorites we studied” Ek says.

The ETH researchers also have a plausible explanation for another stardust puzzle: the higher abundance of material from red giants on Earth compared to Mars or Vesta or other asteroids further out in the solar system. This outer region saw an accumulation of material from supernova explosions.

“When the planets formed, temperatures closer to the Sun were very high,” Schönbächler explains. This caused unstable grains of dust, for instance those with an icy crust, to evaporate. The interstellar material contained more of this kind of dust that was destroyed close to the Sun, whereas stardust from red giants was less prone to destruction and hence concentrated there. It is conceivable that dust originating in supernova explosions also evaporates more easily, since it is somewhat smaller. “This allows us to explain why the Earth has the largest enrichment of stardust from red giant stars compared to other bodies in the solar system” Schönbächler says.>>

Re: Red giants & dwarfs

by neufer » Fri Nov 22, 2019 3:39 pm

neufer wrote: Thu Nov 14, 2019 1:29 am
https://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_formation wrote:
<<The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool, oxygen-rich red-giants and carbon grains condensing in the atmospheres of cool carbon stars. Red giants have evolved or altered off the main sequence and have entered the giant phase of their evolution and are the major source of refractory dust grain cores in galaxies. Those refractory cores are also called stardust, which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain cores have condensed within expanding interiors of supernovae, a type of cosmic decompression chamber. Meteoriticists who study refractory stardust (extracted from meteorites) often call it presolar grains but that within meteorites is only a small fraction of all presolar dust. Stardust condenses within the stars via considerably different condensation chemistry than that of the bulk of cosmic dust, which accretes cold onto preexisting dust in dark molecular clouds of the galaxy. Those molecular clouds are very cold, typically less than 50K, so that ices of many kinds may accrete onto grains, in cases only to be destroyed or split apart by radiation and sublimation into a gas component. Finally, as the Solar System formed many interstellar dust grains were further modified by coalescence and chemical reactions in the planetary accretion disk. The history of the various types of grains in the early Solar System is complicated and only partially understood.>>
https://en.wikipedia.org/wiki/SN_1987A#Condensation_of_warm_dust_in_the_ejecta wrote:
<<Although it had been thought more than 50 years ago that dust could form in the ejecta of a core-collapse supernova, which in particular could explain the origin of the dust seen in young galaxies, that was the first time that such a condensation was observed. If SN 1987A is a typical representative of its class then the derived mass of the warm dust formed in the debris of core collapse supernovae is not sufficient to account for all the dust observed in the early universe. However, a much larger reservoir of ~0.25 solar mass of colder dust (at ~26 K) in the ejecta of SN 1987A was found with the Hershel infrared space telescope in 2011 and confirmed by ALMA. Following the confirmation of a large amount of cold dust in the ejecta, ALMA has continued observing SN 1987A. Synchrotron radiation due to shock interaction in the equatorial ring has been measured. Cold (20–100K) carbon monoxide (CO) and silicate molecules (SiO) were observed. The data show that CO and SiO distributions are clumpy, and that different nucleosynthesis products (C, O and Si) are located in different places of the ejecta, indicating the footprints of the stellar interior at the time of the explosion.>>
https://phys.org/news/2019-11-scientists-evidence-neutron-star.html wrote:
Scientists find evidence of missing neutron star
phys.org , November 19, 2019


<<[Astronomers at Cardiff University] claim to have found evidence of the location of a neutron star that was left behind [from] Supernova 1987A. For more than 30 years astronomers have been unable to locate the neutron star—the collapsed leftover core of the giant star—as it has been concealed by a thick cloud of cosmic dust.

Using extremely sharp and sensitive images taken with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in the Atacama Desert of northern Chile, the team have found a particular patch of the dust cloud that is brighter than its surroundings, and which matches the suspected location of the neutron star. The findings have been published in The Astrophysical Journal. Lead author of the study Dr. Phil Cigan, from Cardiff University's School of Physics and Astronomy, said: "For the very first time we can tell that there is a neutron star inside this cloud within the supernova remnant. Its light has been veiled by a very thick cloud of dust, blocking the direct light from the neutron star at many wavelengths like fog masking a spotlight." The supernova explosion that took place at the end of this star's life resulted in huge amounts of gas with a temperature of over a million degrees, but as the gas began to cool down quickly below zero degrees centigrade, some of the gas transformed into a solid, i.e. dust.>>

Re: a steady accumaliting [sic] dust process

by Ann » Fri Nov 15, 2019 6:25 am

neufer wrote: Thu Nov 14, 2019 10:26 pm
Click to play embedded YouTube video.
Ann wrote: Thu Nov 14, 2019 5:11 am
P.S. Sorghum-stenches - from "Ladle Rat Rotten Hut".

I remember reading "Handsel and Gristle", but this one was harder to read.
Thanks for the translation, Art! :D

Ann

Re: a steady accumaliting [sic] dust process

by neufer » Thu Nov 14, 2019 10:26 pm

Click to play embedded YouTube video.
Ann wrote: Thu Nov 14, 2019 5:11 am
P.S. Sorghum-stenches - from "Ladle Rat Rotten Hut".

I remember reading "Handsel and Gristle", but this one was harder to read.

Re: a steady accumaliting [sic] dust process

by Ann » Thu Nov 14, 2019 5:11 am

neufer wrote: Thu Nov 14, 2019 4:19 am
Ann wrote: Thu Nov 14, 2019 3:07 am
If you have to explain why I should laugh, then it isn't as funny?

And if you explain what you mean, then it isn't, I guess, as intellectually stimulating and illuminating as if you don't?
The fact of the matter is...
  • I really thought the "sillyworm 2" post was sort of interesting:
Image
sillyworm 2 wrote: Wed Nov 13, 2019 1:04 pm
So much dust from so many dying stars.

Wrapping my mind around this. Is this a steady accumalitive [sic] process or could
there have been more stars dying earlier when the galaxy was just forming?
Under such sorghum-stenches, I felt that (with a little research) I could
come up with an answer to s2's question(, at least, to my own satisfaction).

Unfortunately, this turned out not to be the case.

However, I had spent too much time not to post something that was at least
as illuminating as own your post... but that had the advantage of a nice NKC video.

Unfortunately, rather than simply enjoying the nice NKC video, you had to
"make a federal case of this" (when clearly neither of us knew what we were talking about).

Neither of us? :?: (reacting) :arrow:

Ann

P.S. Sorghum-stenches - from "Ladle Rat Rotten Hut". I remember reading "Handsel and Gristle", but this one was harder to read.

a steady accumaliting [sic] dust process

by neufer » Thu Nov 14, 2019 4:19 am

Ann wrote: Thu Nov 14, 2019 3:07 am
If you have to explain why I should laugh, then it isn't as funny?

And if you explain what you mean, then it isn't, I guess, as intellectually stimulating and illuminating as if you don't?
The fact of the matter is...
  • I really thought the "sillyworm 2" post was sort of interesting:
Image
sillyworm 2 wrote: Wed Nov 13, 2019 1:04 pm
So much dust from so many dying stars.

Wrapping my mind around this. Is this a steady accumalitive [sic] process or could
there have been more stars dying earlier when the galaxy was just forming?
Under such sorghum-stenches, I felt that (with a little research) I could
come up with an answer to s2's question(, at least, to my own satisfaction).

Unfortunately, this turned out not to be the case.

However, I had spent too much time not to post something that was at least
as illuminating as own your post... but that had the advantage of a nice NKC video.

Unfortunately, rather than simply enjoying the nice NKC video, you had to
"make a federal case of this" (when clearly neither of us knew what we were talking about).

Re: Red giants & dwarfs

by Ann » Thu Nov 14, 2019 3:07 am

neufer wrote: Thu Nov 14, 2019 2:35 am
Ann wrote: Thu Nov 14, 2019 1:53 am
Interesting info on the red giants, Art.

But why is your text a reply to what I said about red dwarfs?
If I have to explain what I post then it isn't as funny.
A comparison of stellar sizes and masses.
Credit: NASA, ESA and A. Feild
If you have to explain why I should laugh, then it isn't as funny?

And if you explain what you mean, then it isn't, I guess, as intellectually stimulating and illuminating as if you don't?

Hope you took notes, because there will be a test tomorrow!
© EtiAmmos #FO21178418

Re: Red giants & dwarfs

by neufer » Thu Nov 14, 2019 2:35 am

Ann wrote: Thu Nov 14, 2019 1:53 am
Interesting info on the red giants, Art.

But why is your text a reply to what I said about red dwarfs?
If I have to explain what I post then it isn't as funny.

Re: Red giants & dwarfs

by Ann » Thu Nov 14, 2019 1:53 am

neufer wrote: Thu Nov 14, 2019 1:29 am
Ann wrote: Wed Nov 13, 2019 3:18 pm .
...most of the gas is locked up inside little red dwarfs, which are as common as dirt in the cosmos, and which jealousy guard their supply of gas without letting the Universe recycle it. To the best of our knowledge, not a single M-type red dwarf has ever "died a natural death" since the Universe was born in the Big Bang. A few may have fallen into black holes, others may have merged with other stars and become massive enough to actually evolve into red giants. But left on their own, the red dwarfs may live as long as the Universe.
https://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_formation wrote:
Click to play embedded YouTube video.
<<The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool, oxygen-rich red-giants and carbon grains condensing in the atmospheres of cool carbon stars. Red giants have evolved or altered off the main sequence and have entered the giant phase of their evolution and are the major source of refractory dust grain cores in galaxies. Those refractory cores are also called stardust, which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain cores have condensed within expanding interiors of supernovae, a type of cosmic decompression chamber. Meteoriticists who study refractory stardust (extracted from meteorites) often call it presolar grains but that within meteorites is only a small fraction of all presolar dust. Stardust condenses within the stars via considerably different condensation chemistry than that of the bulk of cosmic dust, which accretes cold onto preexisting dust in dark molecular clouds of the galaxy. Those molecular clouds are very cold, typically less than 50K, so that ices of many kinds may accrete onto grains, in cases only to be destroyed or split apart by radiation and sublimation into a gas component. Finally, as the Solar System formed many interstellar dust grains were further modified by coalescence and chemical reactions in the planetary accretion disk. The history of the various types of grains in the early Solar System is complicated and only partially understood.>>
Interesting info on the red giants, Art. But why is your text a reply to what I said about red dwarfs?

Ann

Red giants & dwarfs

by neufer » Thu Nov 14, 2019 1:29 am

Ann wrote: Wed Nov 13, 2019 3:18 pm .
...most of the gas is locked up inside little red dwarfs, which are as common as dirt in the cosmos, and which jealousy guard their supply of gas without letting the Universe recycle it. To the best of our knowledge, not a single M-type red dwarf has ever "died a natural death" since the Universe was born in the Big Bang. A few may have fallen into black holes, others may have merged with other stars and become massive enough to actually evolve into red giants. But left on their own, the red dwarfs may live as long as the Universe.
https://en.wikipedia.org/wiki/Cosmic_dust#Dust_grain_formation wrote:
Click to play embedded YouTube video.
<<The large grains in interstellar space are probably complex, with refractory cores that condensed within stellar outflows topped by layers acquired during incursions into cold dense interstellar clouds. That cyclic process of growth and destruction outside of the clouds has been modeled to demonstrate that the cores live much longer than the average lifetime of dust mass. Those cores mostly start with silicate particles condensing in the atmospheres of cool, oxygen-rich red-giants and carbon grains condensing in the atmospheres of cool carbon stars. Red giants have evolved or altered off the main sequence and have entered the giant phase of their evolution and are the major source of refractory dust grain cores in galaxies. Those refractory cores are also called stardust, which is a scientific term for the small fraction of cosmic dust that condensed thermally within stellar gases as they were ejected from the stars. Several percent of refractory grain cores have condensed within expanding interiors of supernovae, a type of cosmic decompression chamber. Meteoriticists who study refractory stardust (extracted from meteorites) often call it presolar grains but that within meteorites is only a small fraction of all presolar dust. Stardust condenses within the stars via considerably different condensation chemistry than that of the bulk of cosmic dust, which accretes cold onto preexisting dust in dark molecular clouds of the galaxy. Those molecular clouds are very cold, typically less than 50K, so that ices of many kinds may accrete onto grains, in cases only to be destroyed or split apart by radiation and sublimation into a gas component. Finally, as the Solar System formed many interstellar dust grains were further modified by coalescence and chemical reactions in the planetary accretion disk. The history of the various types of grains in the early Solar System is complicated and only partially understood.>>

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by sillyworm 2 » Wed Nov 13, 2019 8:34 pm

Thank you Ann!!!!!!

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by Ann » Wed Nov 13, 2019 3:18 pm

sillyworm 2 wrote: Wed Nov 13, 2019 1:04 pm So much dust from so many dying stars.Wrapping my mind around this.Is this a steady accumalitive process or could there have been more stars dying earlier when the galaxy was just forming?
Well, astronomers talk about "cosmic noon, when star formation peaked in the Universe. This happened when the Universe was around 3.5 billion years old, or about 10 billion years ago.
Joanna Bridge of Astrobites wrote:

The last two decades of galaxy research have made it very clear that star formation in galaxies peaked at a redshift of z ~ 2, which occurred about 3.5 billion years after the Big Bang. In the approximately 10 billions years since then, the number of stars forming per year, or star formation rate, has been universally decreasing. This peak in star forming activity at z ~ 2 is often referred to as “cosmic noon.”
Star formation in the early Universe.
(Image: © NASA/ESA/ESO/Wolfram Freudling et al. (STECF))
What this means is that most galaxies, including NGC 3717 and the Milky Way, have most certainly formed most of their stars in the distant past. Of course, star formation didn't stop 3.5 billion years ago - not by any means! But for the Universe as a whole, the rate of star formation has declined during the last ten billion years. And for galaxies with overall red colors and little obvious star formation, we can be sure that they formed almost all their stars in the past.

As for gas and dust, that is an interesting question. The amount of gas has most certainly steadily decreased in the Universe. That is because star formation robs the Universe of "free gas", as gas gets locked up inside stars. Massive stars give back most of their gas to the Universe as they explode as supernovas. Even stars a little more massive than the Sun, and stars no more massive than the Sun, give back a lot of gas to the Universe as they swell into red giants and then "slough off" much of their gaseous outer atmospheres, which are briefly lit up as shimmering planetary nebulas.

But most of the gas is locked up inside little red dwarfs, which are as common as dirt in the cosmos, and which jealousy guard their supply of gas without letting the Universe recycle it. To the best of our knowledge, not a single M-type red dwarf has ever "died a natural death" since the Universe was born in the Big Bang. A few may have fallen into black holes, others may have merged with other stars and become massive enough to actually evolve into red giants. But left on their own, the red dwarfs may live as long as the Universe.

So, as more stars form, less and less of the gas that was created in the Big Bang is available for star formation. Dust, by contrast, accumulates in the Universe, as various "metals" (elements more massive than hydrogen and helium) are formed inside stars, in supernova explosions and in processes going on inside M-type red giants.

Galaxy cluster Abell 2218. NASA, ESA, and Johan Richard (Caltech, USA).
Acknowledgement: Davide de Martin & James Long
So why is it that some galaxies appear to lack dust?

Take a look at galaxy cluster Abell 2218. You can see, if you look carefully, that while some of the galaxies do show clear signs of dust, many of the galaxies appear to be dust free. Yet we know that they must once have contained dust, because dust is a by-product of star formation and also of star death.

So where did the dust go?

The way I understand it, the dust is still there, but it is widely scattered and not gathered into clumps or dust lanes like they are in almost all spiral galaxies. The way I understand it, hot and violent processes related to black holes, particularly supermassive black holes, prevent the dust (and gas) from "settling down" and cooling, which is necessary for star formation. For myself, I picture the gas and dust in elliptical and lenticular galaxies as being constantly battered by a relentless hot wind.

Ann

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by sillyworm 2 » Wed Nov 13, 2019 1:04 pm

So much dust from so many dying stars.Wrapping my mind around this.Is this a steady accumalitive process or could there have been more stars dying earlier when the galaxy was just forming?

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by shaileshs » Wed Nov 13, 2019 4:10 am

TheOtherBruce wrote: Tue Nov 12, 2019 11:32 pm Something I've always wondered in large-scale galaxy images like this; are the groups of blue specks we see individual hot blue stars, or complete compact clusters of hot blue stars? There was an APOD some time back featuring a massive multi-megapixel image of the Andromeda galaxy, and I was never sure there either. This is a lot further away, though, so I find it hard to imagine that we can image single stars at such a distance.
I personally don't think there's a way to see/identify individual star in such galaxies at such long distances (60 million light years) unless the stars are soooooooooooo powerful (almost close to Supernova). Most blue regions seem to be "star clusters" (forming new stars). Some explanation and example given here - https://www.nasa.gov/multimedia/imagega ... _1513.html

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by TheOtherBruce » Tue Nov 12, 2019 11:32 pm

Something I've always wondered in large-scale galaxy images like this; are the groups of blue specks we see individual hot blue stars, or complete compact clusters of hot blue stars? There was an APOD some time back featuring a massive multi-megapixel image of the Andromeda galaxy, and I was never sure there either. This is a lot further away, though, so I find it hard to imagine that we can image single stars at such a distance.

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by orin stepanek » Tue Nov 12, 2019 8:45 pm

neufer wrote: Tue Nov 12, 2019 5:30 pm
orin stepanek wrote: Tue Nov 12, 2019 4:58 pm
BDanielMayfield wrote: Tue Nov 12, 2019 4:22 pm
Did anyone else notice something unusual about today's APOD subject? It looks like it has a double dust disk, with a lighter, less dusty strip in the middle. Resembles a double meat hamburger. :chomp:

I wonder what could have caused this doubly thick disk?
Ya! I noticed it! I also thought they came together at the right edge! Kinda like a high spiral arm and a low spiral arm! Bet you'd get some interesting views if you lived in certain places in that galaxy! :mrgreen:
https://www.spacetelescope.org/images/potw1940a/ wrote:
<<NGC 3717 is not captured perfectly edge-on in the image; the nearer part of the galaxy is tilted ever so slightly down, and the far side tilted up. This angle affords a view across the disc and the central bulge (of which only one side is visible).
https://en.wikipedia.org/wiki/ESO_510-G13 wrote:
:arrow: <<NASA's Hubble Space Telescope has captured an image of an unusual edge-on galaxy, ESO 510-G13, revealing remarkable details of its warped dusty disk and showing how colliding galaxies spawn the formation of new generations of stars. The dust and spiral arms of normal spiral galaxies, like our own Milky Way, appear flat when viewed edge-on. This image shows a galaxy that, by contrast, has an unusual twisted disk structure, first seen in ground-based photographs obtained at the European Southern Observatory (ESO) in Chile. ESO 510-G13 lies in the southern constellation Hydra, roughly 150 million light-years from Earth. Details of the structure of ESO 510-G13 are visible because the interstellar dust clouds that trace its disk are silhouetted from behind by light from the galaxy's bright, smooth central bulge. The strong warping of the disk indicates that ESO 510-G13 has recently undergone a collision with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort the structures of the galaxies as their stars, gas, and dust merge together in a process that takes millions of years. Eventually the disturbances will die out, and ESO 510-G13 will become a normal-appearing single galaxy. In the outer regions of ESO 510-G13, especially on the right-hand side of the image, we see that the twisted disk contains not only dark dust, but also bright clouds of blue stars. This shows that hot, young stars are being formed in the disk. Astronomers believe that the formation of new stars may be triggered by collisions between galaxies, as their interstellar clouds smash together and are compressed. Hubble's Wide Field Planetary Camera 2 (WFPC2) was used to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty spiral arms, the bright bulge, and the blue star-forming regions.>>
Nice; that's a clearer view!

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by BDanielMayfield » Tue Nov 12, 2019 5:53 pm

Ann wrote:An interesting aspect of the dust lane is that it appears to be "double", as if it consisted of two dark relatively thin dust lanes with a broad, lighter swathe in between. Note the peanut shaped bulge of NGC 3717, suggesting that this is a barred galaxy.
Sorry that I had overlooked this part of your above comment Ann.

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by neufer » Tue Nov 12, 2019 5:30 pm

orin stepanek wrote: Tue Nov 12, 2019 4:58 pm
BDanielMayfield wrote: Tue Nov 12, 2019 4:22 pm
Did anyone else notice something unusual about today's APOD subject? It looks like it has a double dust disk, with a lighter, less dusty strip in the middle. Resembles a double meat hamburger. :chomp:

I wonder what could have caused this doubly thick disk?
Ya! I noticed it! I also thought they came together at the right edge! Kinda like a high spiral arm and a low spiral arm! Bet you'd get some interesting views if you lived in certain places in that galaxy! :mrgreen:
https://www.spacetelescope.org/images/potw1940a/ wrote:
<<NGC 3717 is not captured perfectly edge-on in the image; the nearer part of the galaxy is tilted ever so slightly down, and the far side tilted up. This angle affords a view across the disc and the central bulge (of which only one side is visible).
https://en.wikipedia.org/wiki/ESO_510-G13 wrote:
:arrow: <<NASA's Hubble Space Telescope has captured an image of an unusual edge-on galaxy, ESO 510-G13, revealing remarkable details of its warped dusty disk and showing how colliding galaxies spawn the formation of new generations of stars. The dust and spiral arms of normal spiral galaxies, like our own Milky Way, appear flat when viewed edge-on. This image shows a galaxy that, by contrast, has an unusual twisted disk structure, first seen in ground-based photographs obtained at the European Southern Observatory (ESO) in Chile. ESO 510-G13 lies in the southern constellation Hydra, roughly 150 million light-years from Earth. Details of the structure of ESO 510-G13 are visible because the interstellar dust clouds that trace its disk are silhouetted from behind by light from the galaxy's bright, smooth central bulge. The strong warping of the disk indicates that ESO 510-G13 has recently undergone a collision with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort the structures of the galaxies as their stars, gas, and dust merge together in a process that takes millions of years. Eventually the disturbances will die out, and ESO 510-G13 will become a normal-appearing single galaxy. In the outer regions of ESO 510-G13, especially on the right-hand side of the image, we see that the twisted disk contains not only dark dust, but also bright clouds of blue stars. This shows that hot, young stars are being formed in the disk. Astronomers believe that the formation of new stars may be triggered by collisions between galaxies, as their interstellar clouds smash together and are compressed. Hubble's Wide Field Planetary Camera 2 (WFPC2) was used to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty spiral arms, the bright bulge, and the blue star-forming regions.>>

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by orin stepanek » Tue Nov 12, 2019 4:58 pm

BDanielMayfield wrote: Tue Nov 12, 2019 4:22 pm Did anyone else notice something unusual about today's APOD subject? It looks like it has a double dust disk, with a lighter, less dusty strip in the middle. Resembles a double meat hamburger. :chomp:

I wonder what could have caused this doubly thick disk?

Bruce
Ya! I noticed it! I also thought they came together at the right edge! Kinda like a high spiral arm and a low spiral arm! Bet you'd get some interesting views if you lived in certain places in that galaxy! :mrgreen:

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by DL MARTIN » Tue Nov 12, 2019 4:34 pm

Since we don't know about dark energy and dark matter, why don't we use the term 'dark time' to describe the difference between source and cognition?

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by BDanielMayfield » Tue Nov 12, 2019 4:22 pm

Did anyone else notice something unusual about today's APOD subject? It looks like it has a double dust disk, with a lighter, less dusty strip in the middle. Resembles a double meat hamburger. :chomp:

I wonder what could have caused this doubly thick disk?

Bruce

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by neufer » Tue Nov 12, 2019 4:12 pm

Chris Peterson wrote: Tue Nov 12, 2019 2:36 pm
orin stepanek wrote: Tue Nov 12, 2019 2:03 pm
I guess it depends on your perspective!
Helium atom image from search engine!th.jpg

To me it looks like a pinwheel! & the electrons do orbit
around the neutron & proton! JMHO!
No, electrons do not orbit around the nucleus.
They exist in orbitals, which are lobe shaped regions which define probability zones.
In any event, those symmetrically lobed orbitals that remind
Orin of a pinwheel represent electrons with zero angular rotation.
  • Maybe a pinwheel f-block electron(...maybe).
https://en.wikipedia.org/wiki/Block_(periodic_table)#f-block wrote:
<<A block of the periodic table is a set of chemical elements having their differentiating electrons predominately in the same type of atomic orbital. Each block is named after its characteristic orbital: s-block; p-block; d-block; and f-block. The block names (s, p, d and f) are derived from the spectroscopic notation for the value of an electron's azimuthal quantum number: sharp (0), principal (1), diffuse (2), or fundamental (3). Succeeding notations proceed in alphabetical order, as g, h, etc.

Click to play embedded YouTube video.
The f-block appears as a footnote in a standard 18-column table but is located at the center-left of a 32-column full width table. While these elements are generally not considered part of any group some authors consider them to be part of group 3. They are sometimes called inner transition metals because they provide a transition between the s-block and d-block in the 6th and 7th row (period), in the same way that the d-block transition metals provide a transitional bridge between the s-block and p-block in the 4th and 5th rows.

The f-block elements come in two series, in periods 6 and 7. All are metals. The f-orbital electrons are largely inactive in determining the chemistry of the period 6 f-block elements. Their chemical properties are mostly determined by a single d and two s-orbital electrons. Consequently, there is less chemical variability within this series of elements. Among the early period 7 f-block elements, the energies of the 5f, 7s and 6d shells are quite similar; consequently these elements tend to show as much chemical variability as their transition metals analogues. The later f-block elements behave more like their period 6 counterparts.

The f-block elements are unified by mostly having one or more electrons in an inner f-orbital. Of the f-orbitals, five have six lobes each, and the sixth looks like a dumbbell with a donut with two rings. They can contain up to seven pairs of electrons hence the block occupies fourteen columns in the periodic table. They are not assigned group numbers, since vertical periodic trends cannot be discerned in a "group" of two elements.

The two 14-member rows of the f-block elements are sometimes confused with the lanthanides and the actinides, which are names for sets of elements based on chemical properties more so than electron configurations. The lanthanides are the 15 elements running from La to Lu; the actinides are the 15 elements running from Ac to Lr.>>

Re: APOD: NGC 3717: A Nearly Sideways Spiral... (2019 Nov 12)

by orin stepanek » Tue Nov 12, 2019 3:31 pm

Thanks Art & Chris! Guess I'm not too old to learn a thing or more! Hope I didn't confuse anyone! OBTW Is this how confusing the atom is? https://www.youtube.com/watch?v=EOHYT5q5lhQ

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