APOD: Messier 61 Close Up (2019 Aug 28)

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APOD: Messier 61 Close Up (2019 Aug 28)

Post by APOD Robot » Wed Aug 28, 2019 4:12 am

Image Messier 61 Close Up

Explanation: Image data from the Hubble Space Telescope, the European Southern Observatory, and small telescopes on planet Earth are combined in this magnificent portrait of face-on spiral galaxy Messier 61 (M61). A mere 55 million light-years away in the Virgo Cluster of Galaxies, M61 is also known as NGC 4303. It's considered to be an example of a barred spiral galaxy similar to our own Milky Way. Like other spiral galaxies, M61 also features sweeping spiral arms, cosmic dust lanes, pinkish star forming regions, and young blue star clusters. The bright galactic core is offset to the left in this 50 thousand light-year wide close-up.

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Ann
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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by Ann » Wed Aug 28, 2019 4:32 am

M61 is a gorgeous spiral, and it looks even more gorgeous in the Hubble/Gendler/Colombari portrait of it.

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by Tara_Li » Wed Aug 28, 2019 5:52 am

To my eye, that core region looks abnormally small - is that an effect of the wavelength, or is the core just unusually compact?

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by orin stepanek » Wed Aug 28, 2019 11:10 am

Tara_Li wrote:
Wed Aug 28, 2019 5:52 am
To my eye, that core region looks abnormally small - is that an effect of the wavelength, or is the core just unusually compact?
Probably depends on the size of the supermassive black hole!!
Orin

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by Ann » Wed Aug 28, 2019 11:19 am

Tara_Li wrote:
Wed Aug 28, 2019 5:52 am
To my eye, that core region looks abnormally small - is that an effect of the wavelength, or is the core just unusually compact?
Messier 61. ESA/Hubble & NASA.
Acknowledgements: G. Chapdelaine, L. Limatola, and R. Gendler.

Galactic cores are usually quite compact, but the yellowish, elongated bulge (really a bar) of M61 is not that small.

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NCTom

Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by NCTom » Wed Aug 28, 2019 11:26 am

Thanks Ann. That helps a lot. I was wondering the same thing as the bar was not immediately obvious.

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SAB story

Post by neufer » Wed Aug 28, 2019 12:48 pm

https://en.wikipedia.org/wiki/Messier_61 wrote:

<<Messier 61 is an intermediate barred spiral galaxy: i.e., a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy. It is designated as SAB in the galaxy morphological classification system devised by Gerard de Vaucouleurs. Subtypes are labeled as SAB0, SABa, SABb, or SABc, following a sequence analogous to the Hubble sequence for barred and unbarred spirals. The subtype (0, a, b, or c) is based on the relative prominence of the central bulge and how tightly wound the spiral arms are.

M61 belongs to a smaller subgroup known as the S Cloud. The morphological classification of SAB(rs)bc indicates a weakly-barred spiral (SAB) with the suggestion of a ring structure (rs) and moderate to loosely wound spiral arms. It has an active galactic nucleus and is classified as a starburst galaxy containing a massive nuclear star cluster with an estimated mass of 105 solar masses and an age of 4 million years, as well as a central candidate supermassive black hole weighing around 5×106 M☉ solar masses. It cohabits with an older massive star cluster as well as a likely older starburst. Evidence of significant star formation and active bright nebulae appears across M61's disk. Unlike most late-type spiral galaxies within the Virgo Cluster, M61 shows an unusual abundance of neutral hydrogen (H I).>>
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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by dlw » Wed Aug 28, 2019 5:53 pm

Beautiful image!
FWIW I noted a very cute little (apparently) barred spiral galaxy near the right edge. Presumably much farther away than M61.
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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by DL MARTIN » Wed Aug 28, 2019 6:55 pm

Again, without context doubt remains that 2=2=4. In other words, if the fact that what is being visualized is 55 millions years ago (but not stated), then how can one validate conclusions as if in the present. To exclude the time variable (t=o) is to dismiss evolution. This just doesn't add up.

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by TrickyGlow » Wed Aug 28, 2019 9:48 pm

I was gonna ask something but then I remembered I just saw the galaxy type chart and am laughing my ass off at the SAD SAM galaxy types.

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by Ann » Wed Aug 28, 2019 10:01 pm

DL MARTIN wrote:
Wed Aug 28, 2019 6:55 pm
Again, without context doubt remains that 2=2=4. In other words, if the fact that what is being visualized is 55 millions years ago (but not stated), then how can one validate conclusions as if in the present. To exclude the time variable (t=o) is to dismiss evolution. This just doesn't add up.
55 million years isn't that long in the life of most stars. Admittedly, it can be very long, and more than the lifetime, of a massive star. The light that we see from M61 is dominated by the emission of massive stars, and many of them will have died since they produced the light that reaches us today. On the other hand, the "frozen in time" image of M61 that is the only picture we can ever receive of it gives every impression of making many new stars "now". So even if many of the bright stars that we can see in our "snapshot in time" of M61 have died by "now", many other bright stars have undoubtedly been born.

But it is really meaningless to talk about "now" when we discuss other galaxies. When I was 15 years old, I saw M31, the Andromeda galaxy, through a pair of smallish binoculars. My first view of Andromeda is still the most magical thing that I have ever seen in the sky. What made the experience so powerful was that I felt totally certain that there was another "person" in that blurry spot in the sky. Someone was alive in there. There were habitated worlds in there, and someone in there was actually looking back at me. I felt an overpoweringly strong urge to wave at the person that I was "looking at".

The memory has always stayed with me, but as I kept thinking of waving at the "person" I had imagined in the blurry spot that was Andromeda, I began realizing how impossible my greeting actually was. If by some magical means the waving of my hand could actually be translated into a signal that eventually reached the person I had imagined in Andromeda, then it would take two million years for my greeting to arrive at its destination in our sister galaxy.

If the person that I had waved at had a life span that was even remotely as short as my own, then that person would have died eons before my wave signal actually reached him or her. And if that person waved back at me at that moment when I felt that incredible connection reaching from myself to Andromeda, then that person's wave signal wouldn't reach the Earth until I had been dead for about two million years.

It's useless to talk about what things are like "now" in other galaxies. We get the pictures of them that we get based on the photons emitted by them some time in the past, and that is the best we can do. That is all we can do.

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by DL MARTIN » Wed Aug 28, 2019 11:34 pm

Thank you Ann for a thoughtful and gracious reply. Unfortunately I'm of the opinion that the astronomy community sells the idea that everything is current events and, by extension, approachable. When the time context is applied however, the 'current events' concept doesn't add up. I view it as if i'm looking out in my garden and viewing the lawn as evidence that the Earth is flat. Events that take place between, for example, the light from Andromeda reaching us and in Andromeda itself seem unaccounted for. The failure to acknowledge this analytic shortcoming undermines astronomy's fundamental credibility.

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by Chris Peterson » Thu Aug 29, 2019 1:44 pm

DL MARTIN wrote:
Wed Aug 28, 2019 11:34 pm
Thank you Ann for a thoughtful and gracious reply. Unfortunately I'm of the opinion that the astronomy community sells the idea that everything is current events and, by extension, approachable. When the time context is applied however, the 'current events' concept doesn't add up. I view it as if i'm looking out in my garden and viewing the lawn as evidence that the Earth is flat. Events that take place between, for example, the light from Andromeda reaching us and in Andromeda itself seem unaccounted for. The failure to acknowledge this analytic shortcoming undermines astronomy's fundamental credibility.
Not everything is treated as "current". But something like this image is, because... well, for most scientific purposes, it is. And where it isn't... as with intervening events... those things are considered.
Chris

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Re: APOD: Messier 61 Close Up (2019 Aug 28)

Post by noahstrickland@gmail.com » Thu Aug 29, 2019 11:17 pm

Have been looking at APOD for a decade now if not more, never posted or thought to post. The reason I am commenting this evening is to say thanks for having this website in the first place and secondly to say that this is maybe the best APOD pic yet. For real, it's stunning and amazing and I really can't think of a better one.

I do love me some galaxy pics though, so I am definitely biased in my opinion.

keep up the awesome work!