APOD: Seven Dusty Sisters (2018 May 28)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 3364
Joined: Fri Dec 04, 2009 3:27 am

APOD: Seven Dusty Sisters (2018 May 28)

Post by APOD Robot » Mon May 28, 2018 4:10 am

Image Seven Dusty Sisters

Explanation: Is this really the famous Pleaides star cluster? Known for its iconic blue stars, the Pleaides is shown here in infrared light where the surrounding dust outshines the stars. Here three infrared colors have been mapped into visual colors (R=24, G=12, B=4.6 microns). The base images were taken by NASA's orbiting Wide Field Infrared Survey Explorer (WISE) spacecraft. Cataloged as M45 and nicknamed the Seven Sisters, the Pleiades star cluster is by chance situated in a passing dust cloud. The light and winds from the massive Pleiades stars preferentially repels smaller dust particles, causing the dust to become stratified into filaments, as seen. The featured image spans about 20 light years at the distance of the Pleiades, which lies about 450 light years distant toward the constellation of the Bull (Taurus).

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Ann
4725 Å
Posts: 9129
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Ann » Mon May 28, 2018 7:04 am

The most interesting thing about this picture is the stars that are so obvious in infrared light.

I can identify only two of them. One is the K5-type star to the upper left of the blue Pleiades that is so striking and red in the visual light picture. That star is HD 23712, and it is really red and cool, with a B-V index of 1.7.

The other star I can identify is the one that looks so orange and prominent below center and to the left in the infrared picture. That star is TYC 1800 2105 1, also known as V* SY Tau, a long-period variable star that is faint 9th magnitude in visual light. This star is surprisingly non-red in visual light, with a B-V index of only 1.2, way paler than HD 23712. And yet, the long-period variable is so much more infrared than the normal K5-type star.

Perhaps V* SY Tau is a Mira-type variable.
Wikipedia wrote:

Mira A is a well-known example of a category of variable stars known as Mira variables, which are named after it. The 6,000 to 7,000 known stars of this class[23] are all red giants whose surfaces pulsate in such a way as to increase and decrease in brightness over periods ranging from about 80 to more than 1000 days.
...
The total swing in brightness from absolute maximum to absolute minimum (two events which did not occur on the same cycle) is 1700 times. Since Mira emits the vast majority of its radiation in the infrared, its variability in that band is only about two magnitudes. The shape of its light curve is of an increase over about 100 days, and the return to minimum taking twice as long.
...
Infrared VLTI measurements of Mira at phases 0.13, 0.18, 0.26, 0.40, and 0.47, show that the radius varies from 332 R☉ at phase 0.13 just after maximum to 402 R☉ at phase 0.40 approaching minimum. The temperature at phase 0.13 is 3,192 K and 2,918 K at phase 0.26 about halfway from maximum to minimum. The luminosity is calculated to be 9,360 L☉ at phase 0.13 and 8,400 L☉ at phase 0.26.[11]
Fascinatingly, in view of its low temperature, the B-V index of Mira is not particularly high or "red". Its B-V index is only 0.966 ± 0.299, but its V-I (infrared) index is 5.71 ± 0.39. That's infrared!

So maybe that bright orange star at lower left in today's APOD is another Mira!

Ann
Color Commentator

Boomer12k
:---[===] *
Posts: 2354
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Boomer12k » Mon May 28, 2018 8:22 am

WOW...that is soooo cool.... looks like a PHOENIX!!!! There is a "head" to the left side...beneath that is a "MAGICAL MAIDEN" with her right arm raised....her reddish hair flowing back....

:---[===] *

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1066
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by JohnD » Mon May 28, 2018 9:03 am

Ann, Queen of Colour! You confined your comments to the stars; what about the infra-red 'colours'? The APOD caption mentions filaments in the dust, which would be visible in a black and white version of the picture. The colours are just blotches, more like a badly colourised B&W photograph than evidence of stratified layers of dust, energised to produce different wavelengths of IR radiation.

Judy Schmidt of the Planatery Society posted the same view, with the colours assigned to almost the same wavelengths, in 2016, and the result looks a lot less like a child's attempt to use makeup: https://www.flickr.com/photos/geckzilla ... otostream/

John

heehaw

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by heehaw » Mon May 28, 2018 10:38 am

Glad to have JohdD's alternative version, and both together are mind-blowing! It reminds me again what a rut we all get into, thinking that what we see (of ANYTHING) is what "is there". There is ALWAYS a lot more there than what we see. (And don't get me started again about the dark matter!)

Sa Ji Tario

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Sa Ji Tario » Mon May 28, 2018 12:24 pm

For Boomer, I see in the green and blue part the outline of South America corresponding to Chile, Argentina, Uruguay and Paraguay in the green zone and in the upper part a red star where Bogota would be

Anon

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Anon » Mon May 28, 2018 12:34 pm

It appears that something massive below the cluster is generating an impressive bow shock. Too bad the article did not explain it. I

User avatar
Ann
4725 Å
Posts: 9129
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Ann » Mon May 28, 2018 12:51 pm

JohnD wrote:
Mon May 28, 2018 9:03 am
Ann, Queen of Colour! You confined your comments to the stars; what about the infra-red 'colours'? The APOD caption mentions filaments in the dust, which would be visible in a black and white version of the picture. The colours are just blotches, more like a badly colourised B&W photograph than evidence of stratified layers of dust, energised to produce different wavelengths of IR radiation.

Judy Schmidt of the Planatery Society posted the same view, with the colours assigned to almost the same wavelengths, in 2016, and the result looks a lot less like a child's attempt to use makeup: https://www.flickr.com/photos/geckzilla ... otostream/

John
Thanks for calling me the Queen of Colour, John! :D

Why did I only comment on the color of the stars, and not on the colors of the nebulosity? Well, simple. I feel pretty confident that I know the color of stars, because I have spent a lot of time staring at stars through a telescope and memorizing the colors of them. And I feel pretty confident that I can "translate" the B-V index of a star into a "true" visible star color.

But as for the color of nebulas, what do I know? The only color I have ever seen in nebulas was the greenish tinge that I spotted in the Trapezium region in the Orion Nebula. That's it, really. I enjoy looking at pictures of pink nebulas next to bright blue stars, because I think that the color contrast is beautiful. But I have most definitely never spotted a nebula that looked pink through a telescope. So what do I know about the "real" color of nebulas? What ever we mean by "real" colors (when I can't spot them through a telescope)?

And as for infrared colors, what I know about the "true color of them" is zero. Zip. Nada.

Still though, I realize that when it comes to infrared light, false color (and gray scales) is all that we have. Because infrared light itself is colorless (although Chris will tell you that near-infrared light is really red, which I guess might be true. But it's faint and hard to spot.)

Anyway, I generally don't complain when infrared images are colored weirdly, but I generally don't feel strongly inclined to comment on infrared pictures of nebulas, either. I feel like I'm looking at a famous piece of art that doesn't move me much at all, and I just want to shrug and say, okay, what do you expect me to say about it?

But hey, John, you were right! Geck's version of the Pleiades' infrared colors is so much less - well, so much less exaggerated, maybe?

Ann
Color Commentator

User avatar
Ann
4725 Å
Posts: 9129
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Ann » Mon May 28, 2018 12:56 pm

Anon wrote:
Mon May 28, 2018 12:34 pm
It appears that something massive below the cluster is generating an impressive bow shock. Too bad the article did not explain it. I
I'd say that the only massive thing in this particular region of space is the Pleiades cluster itself. So I think it is the Pleiades cluster that is generating the bow shock.

Ann
Color Commentator

User avatar
geckzilla
Ocular Digitator
Posts: 8887
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by geckzilla » Mon May 28, 2018 1:48 pm

It looks really weird. I would have never guessed it was WISE/Spitzer data. The stars were so heavily modified that they look nothing like the original imagery.
Just call me "geck" because "zilla" is like a last name.

BDanielMayfield
Don't bring me down
Posts: 1795
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by BDanielMayfield » Mon May 28, 2018 3:03 pm

geckzilla wrote:
Mon May 28, 2018 1:48 pm
It looks really weird. I would have never guessed it was WISE/Spitzer data. The stars were so heavily modified that they look nothing like the original imagery.
Weird yes, but still I find this to be a very beautiful image, even tho it does resemble a child's watercolor.

As for the stars themselves, the asterism of the Seven Sisters is so overwhelmed by all the dust that they are really hard to even find. I'd love to see a comparable short exposure visible light image so we can see what our eyes see here too.

Bruce
"Happy are the peaceable ... "

fsldgr
Asternaut
Posts: 1
Joined: Mon Mar 06, 2017 9:00 pm

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by fsldgr » Mon May 28, 2018 3:13 pm

Viewing this image from the artist's eye, If you were trying for a truly a beautiful image, you succeeded.
But viewing this image from the scientist's eye, do the colors, in any way, map to chemical elements or molecules or any other information?

BDanielMayfield
Don't bring me down
Posts: 1795
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by BDanielMayfield » Mon May 28, 2018 3:24 pm

fsldgr wrote:
Mon May 28, 2018 3:13 pm
Viewing this image from the artist's eye, If you were trying for a truly a beautiful image, you succeeded.
But viewing this image from the scientist's eye, do the colors, in any way, map to chemical elements or molecules or any other information?
My guess is that the colors map to different temperatures. Good question. I also hope for a more definitive answer.

Bruce
"Happy are the peaceable ... "

User avatar
neufer
Vacationer at Tralfamadore
Posts: 15444
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by neufer » Mon May 28, 2018 4:52 pm

BDanielMayfield wrote:
Mon May 28, 2018 3:24 pm
fsldgr wrote:
Mon May 28, 2018 3:13 pm

Viewing this image from the artist's eye, If you were trying for a truly a beautiful image, you succeeded.
But viewing this image from the scientist's eye, do the colors, in any way, map to chemical elements or molecules or any other information?
My guess is that the colors map to different temperatures. Good question. I also hope for a more definitive answer.

Here three infrared colors have been mapped
into visual colors (R=24, G=12, B=4.6 microns).
  • 3000 K ~ 1 micron
    650 K ~ 4.6 microns
    250 K ~ 12 microns
    125 K ~ 24 microns
Art Neuendorffer

User avatar
neufer
Vacationer at Tralfamadore
Posts: 15444
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by neufer » Mon May 28, 2018 4:57 pm


Pre-K
JohnD wrote:
Mon May 28, 2018 9:03 am

Ann, Queen of Colour! You confined your comments to the stars; what about the infra-red 'colours'? The APOD caption mentions filaments in the dust, which would be visible in a black and white version of the picture. The colours are just blotches, more like a badly colourised B&W photograph than evidence of stratified layers of dust, energised to produce different wavelengths of IR radiation.

Judy Schmidt of the Planatery Society posted the same view, with the colours assigned to almost the same wavelengths, in 2016, and the result looks a lot less like a child's attempt to use makeup:

https://www.flickr.com/photos/geckzilla ... otostream/
Art Neuendorffer

BillBixby
Science Officer
Posts: 113
Joined: Tue Jul 10, 2012 6:57 pm

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by BillBixby » Mon May 28, 2018 5:56 pm

Thank you Art, for the laughter.

I placed the APOD and pre K side-by-side in paint and saved it to my favorite Astro photos file with the title Fun.

User avatar
JohnD
Tea Time, Guv! Cheerio!
Posts: 1066
Joined: Wed Feb 16, 2005 2:11 pm
Location: Lancaster, England

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by JohnD » Mon May 28, 2018 6:53 pm

Yes, Art, exactly what I meant!
John

De58te
Science Officer
Posts: 190
Joined: Mon Sep 30, 2013 6:35 pm

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by De58te » Mon May 28, 2018 7:14 pm

Thanks Ann for identifying the stars and thanks apod for supplying the mouse over of the regular picture of the Pleiades. What I find fascinating is how the stars differ in the two photos. HD 23712 is very white in the first photo but the brightest red in the mouse over. More interesting is V* SY Tau, it is the brightest red in the first photo yet very dim red in the mouse over. It appears to be very different in color to the 3 whitish stars in a triangle shape below it. Yet in normal light, V* SY Tau and the triangle stars are the same color red. I can't tell them apart. Wonder why that is?

User avatar
geckzilla
Ocular Digitator
Posts: 8887
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by geckzilla » Mon May 28, 2018 8:47 pm

BDanielMayfield wrote:
Mon May 28, 2018 3:03 pm
As for the stars themselves, the asterism of the Seven Sisters is so overwhelmed by all the dust that they are really hard to even find.
I find this problematic, because they are not at all overwhelmed by dust in the original data. They seem to have been shrunk with some kind of filter. Fake glowing effects, hazy rings, and way-too-crisp fake diffraction spikes spoil the image. I'm not sure about the colors. They seem overworked. I don't think they actually closely match with the data, though there is some beautiful variation for this nebula in the infrared spectrum. Like, it hasn't just had its saturation increased, colors were totally shifted or unevenly balanced. I personally think it's leaning too heavily on the creative side, but to each their own. Aside from the odd use of color, there are lots of mosaic seams and various filters have been heavily applied. Disclaimer: I have never been a fan of Antonucci's work.
Just call me "geck" because "zilla" is like a last name.

heehaw

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by heehaw » Mon May 28, 2018 9:23 pm

Ann wrote:
Mon May 28, 2018 12:56 pm
Anon wrote:
Mon May 28, 2018 12:34 pm
It appears that something massive below the cluster is generating an impressive bow shock. Too bad the article did not explain it. I
I'd say that the only massive thing in this particular region of space is the Pleiades cluster itself. So I think it is the Pleiades cluster that is generating the bow shock.

Ann
The dark matter?

User avatar
Ann
4725 Å
Posts: 9129
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Ann » Mon May 28, 2018 10:36 pm

heehaw wrote:
Mon May 28, 2018 9:23 pm
Ann wrote:
Mon May 28, 2018 12:56 pm
Anon wrote:
Mon May 28, 2018 12:34 pm
It appears that something massive below the cluster is generating an impressive bow shock. Too bad the article did not explain it. I
I'd say that the only massive thing in this particular region of space is the Pleiades cluster itself. So I think it is the Pleiades cluster that is generating the bow shock.

Ann
The dark matter?
The dark matter hypothesis is possible, of course. That would require the presence of a big clump of dark matter in the area, a clump that would otherwise not affect its surroundings appreciably. Apart from creating a bow shock in the dusty nebula of the Pleiades, that is.

Ann
Color Commentator

User avatar
Ann
4725 Å
Posts: 9129
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Seven Dusty Sisters (2018 May 28)

Post by Ann » Mon May 28, 2018 10:57 pm

De58te wrote:
Mon May 28, 2018 7:14 pm
Thanks Ann for identifying the stars and thanks apod for supplying the mouse over of the regular picture of the Pleiades. What I find fascinating is how the stars differ in the two photos. HD 23712 is very white in the first photo but the brightest red in the mouse over. More interesting is V* SY Tau, it is the brightest red in the first photo yet very dim red in the mouse over. It appears to be very different in color to the 3 whitish stars in a triangle shape below it. Yet in normal light, V* SY Tau and the triangle stars are the same color red. I can't tell them apart. Wonder why that is?
In itself, that might be perfectly normal. The reason is that some stars are extremely "red" in infrared, but not strikingly red in optical light. Other stars are red visually, but not strikingly red in the infrared. A third group of stars are very red both in visual light and in the infrared.

Mira: B-V: 0.966 ± 0.299 V-I: 5.71 ± 0.39

HD 23712: B-V: 1.701 ± 0.001 V-I: 1.71 ± 0.09

T Lyrae: B-V: 5.460 ± 0.510 V-I: 2.91 ± 0.56

Why do some stars have such very red B-V indexes, and such relatively unremarkable V-I indexes? Why do other stars have such very red V-I indexes, and such unremarkable B-V indexes? And why do other stars display almost the same value of their B-V and their V-I indexes?

I don't know. They just do. Clearly these indexes reflect the shape of their light curves.

Ann
Color Commentator