Explanation: The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy. Even at some two and a half million light-years distant, this immense spiral galaxy -- spanning over 200,000 light years -- is visible, although as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, and expansive spiral arms dotted with blue star clusters and red nebulae, are recorded in this stunning telescopic image which combines data from orbiting Hubble with ground-based images from Subaru and Mayall. In only about 5 billion years, the Andromeda galaxy may be even easier to see -- as it will likely span the entire night sky -- just before it merges with our Milky Way Galaxy.
Astrophotographers will normally make the inner parts of the galaxies that they photograph look fainter than they are, and the outer parts look brighter. That way more details are brought out in the galaxy. But it is in a way a portrait that has been tampered with. Of course we always have to tamper with our imagery to bring out details... oh well...
Interestingly, Andromeda is a ring galaxy rather than strictly a spiral galaxy:
I believe that the timescale has been revised, so that M32 is now thought to have plunged through the disk as long ago as some 800 million years. Nevertheless, that was a big splash! And a bigger one still is expected when the Milky Way itself collides with Andromeda some five(?) billion years from now.
<<Spirals are some of the most captivating shapes in the universe. They appear in intricate seashells, carefully constructed spider webs, and even in the curls of ocean waves. Spirals on cosmic scales – as seen in galaxies – are even more arresting, not only for their beauty, but also for the overwhelming amount of information they contain. How do stars and star clusters form? Until recently, a complete answer used to lie out of reach, blocked by gas and dust. Within the first year of operations, NASA’s James Webb Space Telescope will help researchers complete a more detailed sketch of the stellar life cycle with high-resolution infrared-light images of 19 galaxies.
The telescope will also provide a few key “puzzle pieces” that were missing until now. “JWST touches on so many different phases of the stellar life cycle – all in tremendous resolution,” said Janice Lee, Gemini Observatory chief scientist at the National Science Foundation’s NOIRLab in Tucson, Arizona. “Webb will reveal star formation at its very earliest stages, right when gas collapses to form stars and heats up the surrounding dust.”
Lee is joined by David Thilker of the Johns Hopkins University in Baltimore, Maryland, Kathryn Kreckel of Heidelberg University in Germany, and 40 additional members of the multi-wavelength survey program known as PHANGS (Physics at High Angular resolution in Nearby GalaxieS). Their mission? Not only to unravel the mysteries of star formation with Webb’s high-resolution infrared images, but also to share the datasets with the entire astronomical community to accelerate discovery.
PHANGS is novel, in part, because it brought together more than 100 international experts to study star formation from beginning to end. They are targeting galaxies that can be seen face-on from Earth and that are, on average, 50 million light-years away. The large collaboration began with microwave light images of 90 galaxies from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. Astronomers use this data to produce molecular gas maps to study the raw materials for star formation. Once the Very Large Telescope’s Multi Unit Spectroscopic Explorer (MUSE) instrument, also in Chile, came online, they obtained data known as spectra to study later phases of star formation of 19 galaxies, particularly after star clusters have cleared nearby gas and dust. The space-based Hubble Space Telescope has provided visible and ultraviolet light observations of 38 galaxies to add high-resolution images of individual stars and star clusters.
The missing elements, which Webb will fill in, are largely in areas of the galaxies that are obscured by dust – regions where stars are actively beginning to form. “We’re going to clearly see star clusters in the hearts of these dense molecular clouds that before we only had indirect evidence of,” Thilker said. “Webb gives us a way to look inside these ‘star factories’ to see the freshly assembled star clusters and measure their properties before they evolve.”
The new data will also help the team pinpoint the ages of stellar populations in a diverse sample of galaxies, which will help researchers build more accurate statistical models. “We’re always putting the context of the small scales into the big picture of galaxies,” explained Kreckel. “With Webb, we’ll trace the evolutionary sequence of each galaxy’s stars and star clusters.” Another important answer they’re seeking involves the dust surrounding the stars, within the interstellar medium. Webb will help them determine which areas of the gas and dust are associated with specific star-forming regions, and which are free-floating interstellar material. “This couldn't be done before, beyond the nearest galaxies. It will be transformative,” Thilker added. The team is also working to understand the timing of the star-formation cycle. “Timescales are critical in astronomy and physics,” Lee said. “How long does each stage of star formation last? How might those timelines vary in different galaxy environments? We want to measure when these stars free themselves from their gas clouds to understand how star formation is disrupted.”>>
IN the distant future, M31 will merge with OUR galaxy, and dark energy will have sent all other galaxies beyond the horizon: not longer visible to us on Earth. However, well; that will be QUITE a while from now!
heehaw wrote: ↑Wed Jan 19, 2022 7:50 pm
IN the distant future, M31 will merge with OUR galaxy, and dark energy will have sent all other galaxies beyond the horizon: not longer visible to us on Earth. However, well; that will be QUITE a while from now!
Not ALL other galaxies. The galaxies in the Local Group are gravitationally bound. Of course, given enough time, they will all merge as well.
Chris
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Chris L Peterson
Cloudbait Observatory https://www.cloudbait.com
heehaw wrote: ↑Wed Jan 19, 2022 7:50 pm
IN the distant future, M31 will merge with OUR galaxy, and dark energy will have sent all other galaxies beyond the horizon: not longer visible to us on Earth. However, well; that will be QUITE a while from now!
Not ALL other galaxies. The galaxies in the Local Group are gravitationally bound. Of course, given enough time, they will all merge as well.
It is thought to be the composite contributions of the Shapley Concentration and the Great Attractor which contributes to the ~631 km/s Local Group motion.>>
Most high resolution deep field galaxy images comparable to this show up a menagerie of more distant galaxies. But I could only find a few few dim distant spiral candidates. Have these more distant been editted out? Is this an artefact of Andromed covering such an expanse? Or are we looking in the direction of one of these great voids in space?
Newtownian wrote: ↑Thu Jan 20, 2022 9:24 am
Most high resolution deep field galaxy images comparable to this show up a menagerie of more distant galaxies. But I could only find a few few dim distant spiral candidates. Have these more distant been editted out? Is this an artefact of Andromed covering such an expanse? Or are we looking in the direction of one of these great voids in space?
The Andromeda galaxy looms so large in the sky, and the field of view of Hubble is so narrow, that it seems all but certain that Hubble hasn't photographed any background galaxies of Andromeda in this image.
Yes, but ESA/Hubble has studied Andromeda's large halo. Here are two images of small parts of Andromeda's halo, featuring background galaxies:
Newtownian wrote: ↑Thu Jan 20, 2022 9:24 am
Most high resolution deep field galaxy images comparable to this show up a menagerie of more distant galaxies. But I could only find a few few dim distant spiral candidates. Have these more distant been edited out? Is this an artifact of Andromeda covering such an expanse? Or are we looking in the direction of one of these great voids in space?
The Andromeda galaxy looms so large in the sky, and the field of view of Hubble is so narrow, that it seems all but certain that Hubble hasn't photographed any background galaxies of Andromeda in this image.
Yes... this is a low resolution shallow field galaxy image.
NGC 205 (Messier 110) & NGC 221 (Messier 32) are visible
but they are already 100 times dimmer than NGC 224 (Messier 31) .
Every other galaxy in the image are thousands of times dimmer than these two satellite galaxies.
High resolution deep field galaxy images (e.g., the Hubble Ultra-Deep Field)
always zero in on small empty regions of the sky.
M31: The Andromeda Galaxy
Curiously, the inner skewed dust ring seems
