APOD: NGC 3310: A Starburst Spiral Galaxy (2016 Mar 01)

[Ann]

I don't understand you, Chris. Are you saying that the Travis Rector APOD shows "accurate color" while Adam Block's RGB image is "unnatural"?

I'm saying that it's entirely possible that the Rector image shows more accurate color than the Block image. There's no way that I can make that assessment conclusively just looking at the images, however.

Travis Rector's image looks "flat" to me, where all the colors are strongly separated and remain one and the same hue. It sort of resembles the old Dick Tracy movie. Look at the pink Ha features in the Travis Rector image. They are exactly the same shade of pink everywhere. Adam Block's image, however, shows that the Ha regions are more or less mixed with blue starlight. Some Ha regions are all pink in his image, others are purple, and others show a mixture of pink, white, purple and blue. This is exactly what we should expect. In some Ha regions the stars are completely embedded, and the nebula will look all pink. In others the stars are partly or fully revealed and contribute blue light to the nebula.

An unexplained feature of Travis Rector's image is the beige swath of galactic disk stretching from 3 o'clock to 9 o'clock in the image. Like Geck said, this might contain an interesting piece of information about the presence or absence of dust in the disk. But we can only guess at what causes this beige color, since nothing is explained.

Ann

[Chris Peterson]

Travis Rector's image looks "flat" to me, where all the colors are strongly separated and remain one and the same hue. It sort of resembles the old Dick Tracy movie. Look at the pink Ha features in the Travis Rector image. They are exactly the same shade of pink everywhere. Adam Block's image, however, shows that the Ha regions are more or less mixed with blue starlight. Some Ha regions are all pink in his image, others are purple, and others show a mixture of pink, white, purple and blue. This is exactly what we should expect. In some Ha regions the stars are completely embedded, and the nebula will look all pink. In others the stars are partly or fully revealed and contribute blue light to the nebula.

An unexplained feature of Travis Rector's image is the beige swath of galactic disk stretching from 3 o'clock to 9 o'clock in the image. Like Geck said, this might contain an interesting piece of information about the presence or absence of dust in the disk. But we can only guess at what causes this beige color, since nothing is explained.

You see things differently than I do. I see as much range in the Ha color in the Rector image as in the Block image. I think the Ha color is more natural in the Rector image- it's quite oversaturated in the Block image. That creates a color distortion that makes subtle variation more obvious (which is one reason to process this way), but the range is present in both. And all of the blue in the Block image is very unnatural- not at all the color of blue stars. Again, oversaturated. The Rector image looks quite natural to me- the pale blue of hot stars fading to white as we go into the center, but with pink added by the central hydrogen regions. I don't see anything beige, and so I'm not sure what this "swath" you're referring to is.

[DavidLeodis]

I found it odd that on clicking the APOD image (to get a larger version) the image brought up is switched over horizontally!

I'm wondering if there is anything known about the jet-like feature that goes out about to the top left corner in the APOD image (about to the top right corner in the clicked on version)?

[Ann]

I found it odd that on clicking the APOD image (to get a larger version) the image brought up is switched over horizontally!

I'm wondering if there is anything known about the jet-like feature that goes out about to the top left corner in the APOD image (about to the top right corner in the clicked on version)?

The larger version is oriented so that north is up, which is the conventional orientation.

I'm afraid I don't know anything about that jet. But NGC 3310 is known as the Bow and Arrow galaxy, because of that jet and the arc-like feature is it crossing.

Ann

[Visual_Astronomer]

I don't understand you, Chris. Are you saying that the Travis Rector APOD shows "accurate color" while Adam Block's RGB image is "unnatural"?

I'm saying that it's entirely possible that the Rector image shows more accurate color than the Block image. There's no way that I can make that assessment conclusively just looking at the images, however.

Specifically, though, what I was arguing was that an image that displayed photometric color as actual color would require a very carefully constructed false color palette. That is, an image that showed a star's temperature or B-V value as a particular RGB value. It would be a useful image, but nothing close to what could be called accurate color.

Color is created in the brain. There is no such thing as color in the world outside of your head.

Color in an astronomical photo can be rendered aesthetically pleasing, and if it also conveys some scientifically useful data, all the better. But there is no vantage point in space where you could look at this galaxy with your naked eye and see colors like in this photograph.

[Chris Peterson]

Color is created in the brain. There is no such thing as color in the world outside of your head.

Color in an astronomical photo can be rendered aesthetically pleasing, and if it also conveys some scientifically useful data, all the better. But there is no vantage point in space where you could look at this galaxy with your naked eye and see colors like in this photograph.

Exactly my point throughout this discussion.

[DavidLeodis]

I found it odd that on clicking the APOD image (to get a larger version) the image brought up is switched over horizontally!

I'm wondering if there is anything known about the jet-like feature that goes out about to the top left corner in the APOD image (about to the top right corner in the clicked on version)?

The larger version is oriented so that north is up, which is the conventional orientation.

I'm afraid I don't know anything about that jet. But NGC 3310 is known as the Bow and Arrow galaxy, because of that jet and the arc-like feature is it crossing.

Ann

Thanks for your help Ann, which is appreciated .

Before submitting my query I had searched under NGC 3310 but (without going through too many links) none of them mentioned the Bow and Arrow galaxy and it was only when I searched under Bow and Arrow after your information that I finally found some mentions. Unless you already knew of it I hope therefore that you did not spend too much time and effort in your willingness to help me.

[neufer]

[b][color=#0000FF]EGSY8p7 (Hubble and Spitzer, space telescopes)[/color][/b]

---

<<EGSY8p7 is a distant galaxy, with a spectroscopic redshift of z = 8.68, a light travel distance of 13.2 billion light-years from Earth and observed as it existed 570 million years after the Big Bang. In July 2015, EGSY8p7 was announced as the oldest and most-distant known object.

The light of the EGSY8p7 galaxy appears to have been magnified twofold by gravitational lensing in the light's travel to Earth, enabling detecting EGSY8p7, which would not have been possible without the magnification. EGSY8p7's distance from Earth was determined by measuring the redshift of Lyman-alpha emissions. EGSY8p7 is the most distant known detection of hydrogen's Lyman-alpha emissions. The distance of this detection was surprising, because neutral hydrogen (atomic hydrogen) clouds filling the early universe should have absorbed these emissions, even by some hydrogen cloud sources closer to Earth, according to the standard cosmological model. A possible explanation for the detection would be that reionization progressed in a "patchy" manner, rather than homogeneously throughout the universe, creating patches where the EGSY8p7 hydrogen Lyman-alpha emissions could travel to Earth, because there were no neutral hydrogen clouds to absorb the emissions.>>

[Ann]

I found it odd that on clicking the APOD image (to get a larger version) the image brought up is switched over horizontally!

I'm wondering if there is anything known about the jet-like feature that goes out about to the top left corner in the APOD image (about to the top right corner in the clicked on version)?

The larger version is oriented so that north is up, which is the conventional orientation.

I'm afraid I don't know anything about that jet. But NGC 3310 is known as the Bow and Arrow galaxy, because of that jet and the arc-like feature is it crossing.

Ann

Thanks for your help Ann, which is appreciated .

Before submitting my query I had searched under NGC 3310 but (without going through too many links) none of them mentioned the Bow and Arrow galaxy and it was only when I searched under Bow and Arrow after your information that I finally found some mentions. Unless you already knew of it I hope therefore that you did not spend too much time and effort in your willingness to help me.

Don't worry!

I love galaxies, and NGC 3310 is among my very favorite galaxies. I already knew it was called the Bow and Arrow galaxy.

Ann