by Boomer12k » Mon Jun 06, 2016 6:13 am
Ann wrote:I'm very glad that this spiral galaxy and the important research that has been done on two of its constituent kinds of stars is honored with an APOD.
The colors are very well-balanced. The Cepheids are not encircled in the large version of the picture, but I could memorize the star patterns where some of them are located, and then I could easily recognize them by their color and brightness in the large picture. Cepheids are fainter than the brightest blue and red stars in a starforming galaxy, and they are neutral or pale yellow in color, whereas other bright stars in their vicinity are usually either bluish or golden orange.
To my utterly amateur mind, it seems as if there is something systematic about the way the value of the Hubble constant and the rate of the acceleration of the universe has been revised up and down.
The first discovery of the acceleration of the universe was made when two teams studied supernovas Type Ia in galaxies that are much too far away for any of their non-supernova constituent stars to be studied. Let's say this study was centered on the "teenage" era of the universe. The way I remember it, the two teams concluded that the universe was made up of 73% of 74% dark energy, plus dark matter and baryonic matter.
The
next great studies of dark energy and the rate of the universe was carried out first by the WMAP spacecraft, which studied the cosmic microwave background, the baby era of the universe, and concluded that the universe is made up of 72.8% dark energy, plus dark matter and baryonic matter. After WMAP came Planck, whose study of the cosmic microwave background revised the strength of dark energy down to 68.3% of the universe.
But the new study is based of galaxies in a much later era of the universe, where the galaxies are close enough to have their Cepheid stars studied. The strength of dark energy and the rate of the acceleration of the universe is again revised upwards.
Could it be that dark energy is slowly, slowly gaining strength as the universe evolves? Alternatively, could it be that supernova studies, for whatever reason, gives a higher value for dark energy than studies of the cosmic microwave background? Or is the new study just more precise than previous ones, so that it arrives at a more correct value?
Questions, questions. And no answers. Well, I find this very interesting, at least!
Ann
Ann, nice observations... there MAY also be that the "standard candle" of Type 1a Supernova... are now considered....not so standard as thought... PLUS... new techniques, more sensitive equipment, like the new Interferometer... get new readings, thus, new data, totals, figures, and so, things appear to change. Science marches on...
I am sure the new space telescope will give us even some different data than Hubble. We will see more, learn more....
Also, maybe being closer, the Resolution is closer, and the situation clearer...
Nice night tonight, but I am too bushed, and it was a bit windy.
:---[===] *
[quote="Ann"]I'm very glad that this spiral galaxy and the important research that has been done on two of its constituent kinds of stars is honored with an APOD.
The colors are very well-balanced. The Cepheids are not encircled in the large version of the picture, but I could memorize the star patterns where some of them are located, and then I could easily recognize them by their color and brightness in the large picture. Cepheids are fainter than the brightest blue and red stars in a starforming galaxy, and they are neutral or pale yellow in color, whereas other bright stars in their vicinity are usually either bluish or golden orange.
To my utterly amateur mind, it seems as if there is something systematic about the way the value of the Hubble constant and the rate of the acceleration of the universe has been revised up and down. [url=https://en.wikipedia.org/wiki/Dark_energy#Supernovae]The first discovery of the acceleration of the universe was made when two teams studied supernovas Type Ia[/url] in galaxies that are much too far away for any of their non-supernova constituent stars to be studied. Let's say this study was centered on the "teenage" era of the universe. The way I remember it, the two teams concluded that the universe was made up of 73% of 74% dark energy, plus dark matter and baryonic matter.
The [url=https://en.wikipedia.org/wiki/Dark_energy#Supernovae]next great studies of dark energy[/url] and the rate of the universe was carried out first by the WMAP spacecraft, which studied the cosmic microwave background, the baby era of the universe, and concluded that the universe is made up of 72.8% dark energy, plus dark matter and baryonic matter. After WMAP came Planck, whose study of the cosmic microwave background revised the strength of dark energy down to 68.3% of the universe.
But the new study is based of galaxies in a much later era of the universe, where the galaxies are close enough to have their Cepheid stars studied. The strength of dark energy and the rate of the acceleration of the universe is again revised upwards.
Could it be that dark energy is slowly, slowly gaining strength as the universe evolves? Alternatively, could it be that supernova studies, for whatever reason, gives a higher value for dark energy than studies of the cosmic microwave background? Or is the new study just more precise than previous ones, so that it arrives at a more correct value?
Questions, questions. And no answers. Well, I find this very interesting, at least!
Ann[/quote]
Ann, nice observations... there MAY also be that the "standard candle" of Type 1a Supernova... are now considered....not so standard as thought... PLUS... new techniques, more sensitive equipment, like the new Interferometer... get new readings, thus, new data, totals, figures, and so, things appear to change. Science marches on...
I am sure the new space telescope will give us even some different data than Hubble. We will see more, learn more....
Also, maybe being closer, the Resolution is closer, and the situation clearer...
Nice night tonight, but I am too bushed, and it was a bit windy.
:---[===] *