Understanding star-forming galaxies

June 5, 2017, Harvard-Smithsonian Center for Astrophysics
An optical image of the galaxy NGC2718. Astronomers studying the star formation activity in this and other spiral galaxies have confirmed and refined the close correlation, seen among these galaxies and subregions within them, between the numbers of stars present and the rate of making new stars. Credit: Sloan Digital Sky Survey

The more stars a typical spiral galaxy contains, the faster it makes new ones. Astronomers call this relatively tight correlation the "galaxy main sequence." The main sequence might be due simply to the fact that galaxies with more stars have more of everything, including material for making new stars. Alternatively, the mechanisms making new stars could be more efficient in some galaxies, or it could be some combination of these and other possibilities.

Star formation in spiral galaxies generates copious amounts of ultraviolet light that is absorbed by dust and re-radiated at infrared wavelengths, and infrared space missions have enabled scientists to measure more precisely the infrared emission from warm dust in galaxies. As astronomers probe very distant galaxies in the early universe and are forced to rely on measured fluxes rather than visual morphologies to interpret what is going on there, the main-sequence relationship has become an important tool for tracing when and how the universe generated its stars.

CfA astronomers Alexandros Maragkoudakis, Andreas Zezas, Matthew Ashby, and Steve Willner have recently investigated the galaxy main sequence with 246 star-forming galaxies that span a factor of ten thousand in their and star formation rates, systematically exploring the main sequence relationship. They also separately explored discrete regions within these galaxies, including bright knots and circumnuclear regions, to determine whether they also followed a main-sequence-like relationship and if so, whether the correlations were identical or slightly different. Previous authors, for example, had found some clear variations in the correlation between galaxies when grouped by subtype, cosmological age, or other properties.

The CfA astronomers find that even across a wide range of stellar masses, at least for local galaxies the correlation between a galaxy's stellar mass and rate is a tight one. They also find that a similarly close correlation holds within small subregions of , in particular the regions around the supermassive black hole nuclei.

Explore further: Obscured supermassive black holes in galaxies

More information: "The Sub-galactic and Nuclear Main Sequences for Local Star-Forming Galaxies," A. Maragkoudakis, A. Zezas, M. L. N. Ashby and S. P. Willner, MNRAS, 2017. academic.oup.com/mnras/article … 10022848/stw3180.pdf

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9 comments

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RNP
5 / 5 (5) Jun 05, 2017
An open access copy of the paper can be found here; https://arxiv.org...0085.pdf
FredJose
1.6 / 5 (7) Jun 05, 2017
the main-sequence relationship has become an important tool for tracing when and how the universe generated its stars.

It really, really doesn;'t help if one cannot show how it is possible for a star to pop into existence from a cloud of gas - all by itself. It truly should be THE first step that astronomers, cosmologists, cosmogynists and other parties interested in the origin of stars and galaxies should solve.
Right now the whole shebang is build on a house of cards because there exist absolutely ZERO observational let alone theoretical confirming evidence that stars can be "born" from a cloud of gas all by itself via some self-initiated physical process.

When it comes to that part where the equations demand a definitive answer as to the cause of ignition it simply gets skipped over, brushed aside as an exercise for the student. Go figure.
FredJose
1.6 / 5 (7) Jun 05, 2017
the correlation between a galaxy's stellar mass and star formation rate is a tight one.

Sounds terribly much like a circular reasoning being applied here:
The bigger the galaxy, i.e. the more stars it currently displays, the faster it must have produced them in the past and hence we can confirm that it therefore is also doing it at present.
Nevermind that we've never seen it happen ANYWHERE!
Guy_Underbridge
5 / 5 (7) Jun 05, 2017
Nevermind that we've never seen it happen ANYWHERE!
I've never seen a deity spit on the ground and conjure up a human, either. What's your thought on that conjecture.
Tuxford
1 / 5 (5) Jun 05, 2017
The more stars a typical spiral galaxy contains, the faster it makes new ones.

Exactly, as LaViolette predicted in his Continuous Creation model many decades ago.

The CfA astronomers find that even across a wide range of stellar masses, at least for local galaxies the correlation between a galaxy's stellar mass and star formation rate is a tight one. They also find that a similarly close correlation holds within small subregions of galaxies, in particular the regions around the supermassive black hole nuclei.

Exactly. His model predicts the greater the matter density of the local region, the faster new matter is generated within that region. The most extreme case then is deep within supermassive core stars.

Merger maniacs instead contend that the giant galaxies have mostly used up their gas needed for star formation. This observation would seem to contradict this assumption. The article avoids this point, as it is extremely embarrassing for mainstream maniacs.
Da Schneib
not rated yet Jun 05, 2017
This is great stuff. Finding these kinds of correlations is quite important, so that we can test our star formation simulations, and find outliers in the data that tell us more about the conditions that affect star formation. Very important research here. Nothing startling; that will come later when we start looking at the outliers and when the constraints from the data these folks are organizing can be added to the models. The background data are essential to allow the breakthrough research to be done.
FredJose
1 / 5 (4) Jun 05, 2017
Friends, The reason I keep hammering these kind of basic truths is simple - unless you know that there is a creator and that he cares for you, you are very much unlikely to turn to Him for the salvation of your lives.

So here you are making all kinds of gnarly comments but you are still very much unable to get around the basic fact that stars cannot form themselves out of clouds of gas. No matter how scientifically you want to pontificate about fairies and spaghetti monsters, it is still a fact that believing that stars can form themselves out of clouds of gas is a false belief. Strange that you'd hang on so tightly to a pure basic falsehood. And still call it "science" even though you know it's FALSE.

Your creator is concerned precisely about all the falsehoods that have blinded human beings in this manner. Especially the one about the coming day of reckoning. Please reconsider that I'm only talking true facts. Examine for yourselves whether stars can form as preached.
ursiny33
not rated yet Jun 05, 2017
Fred jose in gas cloud iron atoms are a dominant negative charged construction and hydrogen atoms are a dominant positive charged construction those two opposite charges attract to each other magnetically in space build mass in the gass clouds, mass is constructed by magnetic forces of attraction, either the construction of multible atom clusters have a dominant positive or negative charge in those construction total sum of charge , when the clusters grow big enough they collaspe on themselves to bind magnetically in tighter mass's thats how gas cloud build mass,
yep
not rated yet Jun 06, 2017
The reason I keep hammering these kind of basic truths is simple.


Yes Fred it is simple, you have no clue about the origins of your religion and are blinded by your own beliefs.

Here is a wonderful book by a religious scholar. His work was suppressed and career destryed because of what he uncovered about Christianity during his translation of the Dead Sea scrolls and other ancient text.
https://archive.o...djvu.txt

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