by Ann » Fri Apr 09, 2021 6:36 am
My immediate impression, when I looked at today's APOD, was that the picture is probably mostly Robert Gendler's own work, with no great contributions from NASA and Hubble. But now I think that the central part of today's APOD was indeed created from Hubble data.
The picture at right is very obviously a Hubble image, which has been processed by Robert Gendler, with some help from R. Jay GaBany. The picture at left looks much more like an amateur image.
Today's APOD may well be a composite of a an image of the central parts of M106, photographed by Hubble, and amateur data of the outer parts of the galaxy, gathered and processed by Robert Gendler.
Anyway. As for the galaxy itself, the most interesting thing about it is probably its water vapor megamasers. A maser is the microwave equivalent of a laser.
Wikipedia wrote:
M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas. These water vapors give M106 its characteristic purple color.[10] Water masers are useful to observe nuclear accretion disks in active galaxies.
The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy, thereby providing an independent anchor for the cosmic distance ladder.
The description of water masers in M106 is too much math speak for me, but I do get this: Thanks to the water masers, astronomers have an independent way of measuring the distance to M106. It turns out to be 23.7 ± 1.5 million light-years, according to Wikipedia.
M. J. Reid, D. W. Pesce and A. G. Riess wrote:
We find the distance to NGC 4258 to be 7.576 +/- 0.082 (stat.) +/- 0.076 (sys.) Mpc. Using this as the sole source of calibration of the Cepheid-SN Ia distance ladder results in Ho = 72.0 +/- 1.9 km/s/Mpc, and in concert with geometric distances from Milky Way parallaxes and detached eclipsing binaries in the LMC we find Ho = 73.5 +/- 1.4 km/s/Mpc.
Now THAT is important! M106 has been used to nail down the Hubble constant, H
0, which gives us the rate of the expansion of the Universe! The M106 data tells us the the expansion rate of the Universe is around 72-73 km per second per Megaparsec. Okay, okay, I know, that's just the value for the nearby Universe, because the Hubble constant for the baby Universe, the one we detect as the CMB, the Cosmic Microwave Background, is more like 66-67 km/s/Mpc.
The long curved outflows from the core of M106 have been described as "anomalous arms". I guess they have something to do with the water masers of M106. Perhaps they
are the water masers? At the very least, they are certainly
visible in radio emission.
Ann
My immediate impression, when I looked at today's APOD, was that the picture is probably mostly Robert Gendler's own work, with no great contributions from NASA and Hubble. But now I think that the central part of today's APOD was indeed created from Hubble data.
[float=left][img3="M106. Image Credit: NASA, Hubble Legacy Archive, Kitt Peak National Observatory;
Amateur Data & Processing Copyright: Robert Gendler."]https://apod.nasa.gov/apod/image/2104/M106-NOAO-HST-1024c.jpg[/img3][/float][float=right][img3="M106. NASA, ESA, the Hubble Heritage Team (STScI/AURA), and R. Gendler (for the Hubble Heritage Team). Acknowledgment: R. Jay GaBany"]https://upload.wikimedia.org/wikipedia/commons/thumb/2/2d/Messier_106_visible_and_infrared_composite.jpg/1280px-Messier_106_visible_and_infrared_composite.jpg[/img3][/float]
[clear][/clear]
The picture at right is very obviously a Hubble image, which has been processed by Robert Gendler, with some help from R. Jay GaBany. The picture at left looks much more like an amateur image.
Today's APOD may well be a composite of a an image of the central parts of M106, photographed by Hubble, and amateur data of the outer parts of the galaxy, gathered and processed by Robert Gendler.
Anyway. As for the galaxy itself, the most interesting thing about it is probably its water vapor megamasers. A maser is the microwave equivalent of a laser.
[quote][url=https://en.wikipedia.org/wiki/Messier_106#]Wikipedia[/url] wrote:
M106 has a water vapor megamaser (the equivalent of a laser operating in microwave instead of visible light and on a galactic scale) that is seen by the 22-GHz line of ortho-H2O that evidences dense and warm molecular gas. These water vapors give M106 its characteristic purple color.[10] Water masers are useful to observe nuclear accretion disks in active galaxies. [b][color=#FF0000]The water masers in M106 enabled the first case of a direct measurement of the distance to a galaxy, thereby providing an independent anchor for the cosmic distance ladder.[/color][/b][/quote]
The description of water masers in M106 is too much math speak for me, but I do get this: Thanks to the water masers, astronomers have an independent way of measuring the distance to M106. It turns out to be 23.7 ± 1.5 million light-years, according to Wikipedia.
[quote][url=https://arxiv.org/abs/1908.05625]M. J. Reid, D. W. Pesce and A. G. Riess[/url] wrote:
We find the distance to NGC 4258 to be 7.576 +/- 0.082 (stat.) +/- 0.076 (sys.) Mpc. Using this as the sole source of calibration of the Cepheid-SN Ia distance ladder results in Ho = 72.0 +/- 1.9 km/s/Mpc, and in concert with geometric distances from Milky Way parallaxes and detached eclipsing binaries in the LMC we find Ho = 73.5 +/- 1.4 km/s/Mpc.[/quote]
Now THAT is important! M106 has been used to nail down the Hubble constant, H[sub][size=85]0[/size][/sub], which gives us the rate of the expansion of the Universe! The M106 data tells us the the expansion rate of the Universe is around 72-73 km per second per Megaparsec. Okay, okay, I know, that's just the value for the nearby Universe, because the Hubble constant for the baby Universe, the one we detect as the CMB, the Cosmic Microwave Background, is more like 66-67 km/s/Mpc.
[float=left][img3="M106 is X-ray, optical, infrared and radio emission. Credit: X-ray: NASA/CXC/Caltech/P.Ogle et al; Optical: NASA/STScI & R.Gendler; IR: NASA/JPL-Caltech; Radio: NSF/NRAO/VLA."]https://chandra.harvard.edu/photo/2014/m106/m106_w11.jpg[/img3][/float]
[clear][/clear]
The long curved outflows from the core of M106 have been described as "anomalous arms". I guess they have something to do with the water masers of M106. Perhaps they [b][i]are [/i][/b]the water masers? At the very least, they are certainly [url=https://chandra.harvard.edu/photo/2014/m106/]visible in radio emission[/url].
Ann