(From NASA, ESA, CSA, STScI; used w/o permission.)
(The Cartwheel galaxy group, 500,000 light-years out, in the constellation Scorpius.
(James Webb Space Telescope image released by NASA (August 2, 2022))
I’ll be looking at some of the first pictures sent back from the James Webb Space Telescope, starting with the Cartwheel Galaxy.
Update: August 7, 2022
I became aware, after finishing “James Webb Space Telescope Early Results,” that a “top scientist” had told his social media followers that a slice of choizo was a JWST image of Proxima Centauri. (July 31, 2022) Etienne KLEIN — @EtienneKlein — Photo de Proxima du Centaure….)
“Top scientist admits ‘space telescope image’ was actually a slice of chorizo“
Toyin Owoseje, CNN (Updated 5:46 PM ET, Fri August 5, 2022)“A French scientist has apologized after tweeting a photo of a slice of chorizo, claiming it was an image of a distant star taken by the James Webb Space Telescope.
“Étienne Klein, a celebrated physicist and director at France’s Alternative Energies and Atomic Energy Commission, shared the image of the spicy Spanish sausage on Twitter last week, praising the ‘level of detail’ it provided….
“…Klein admitted later in a series of follow-up tweets that the image was, in fact, a close-up of a slice of chorizo taken against a black background….”
The CNN article explains that the “celebrated physicist” had a good reason for the hoax. A reason that seemed good during “cocktail hour,” at any rate.
The ‘Proxima Chorizo’ image has been getting considerable attention in news media.
That, and perhaps an over-abundance of caution, has inspired the following statement.
I am reasonably sure that NASA, the European Space Agency and the James Webb Space Telescope Team are not trying to pass off photographs of a pizza as JWST images of the Cartwheel Galaxy.
Now, back to this week’s post.
Astronomers have known about the Cartwheel Galaxy at least since 1941, when Fritz Zwicky photographed the “cartwheel” ring. He’d been using the 18-inch Schmidt telescope on Mount Palomar.
I gather that the 1941 image showed the galaxy’s outer ring, a bright patch at the center, and not much else.
Rings, Spokes and Explanations
(From STX, STScI, NASA; used w/o permission.)
(The Cartwheel galaxy group (left), Cartwheel Galaxy in infrared light. (1996))
Since then, astronomers learned that the Cartwheel Galaxy is about 500,000 light-years away, 144,300 light-years across, and the largest of a group of four galaxies.
Besides the outer and inner rings, the Cartwheel Galaxy has at least two sets of ‘spokes.’
We’re pretty sure that the Cartwheel Galaxy’s rings formed when one of the smaller galaxies in the group fell through the Cartwheel. Which was a normal spiral galaxy before the collision.
On the other hand, maybe a Jeans instability led to the Cartwheel’s current look.
Jeans instability has nothing to do with denim slacks. It’s a relationship between sound waves, gravity and density described by Sir James Hopwood Jeans in 1902.
I gather that it’s also controversial, or was. Maybe that’s why more scientists figure the collision explanation is correct. Or part of the reason, at any rate.1
“Consequences of the Jeans Instability
“Let’s evaluate the Jeans length and mass, Equations (23) and (24), for parameters of astrophysical interest. Plugging in numbers typical of dense molecular cores (with particle mass m = 3.3 × 10−24 g), we obtain [about three square inches of equations omitted] where cs = 260 m/s for T = 10 K and γ = 5/3, although given the effectiveness of cooling in maintaining constant temperature, a better approximation might be the isothermal γ = 1, as assumed in S&G, in which case cs ≈ 200 m/s….”
(“Jeans Instability and Gravitational Collapse,” Physics 431, Drexel University College of Arts and Sciences)
One reason I had for quoting that bit from “Jeans Instability and Gravitational Collapse” was showing how many factors go into figuring out what goes on when galaxies collide.
Another was getting some use out of the time I spent finding what I could about Jeans instability. Now let’s take a closer look at the Cartwheel Galaxy.
A Galaxy of a Different Color
(From NASA, ESA, CSA, STScI; used w/o permission.)
(The Cartwheel Galaxy, detail showing ‘spokes.’
(James Webb Space Telescope image released by NASA (August 2, 2022))
That’s a detail from the first image.
These ‘spokes’ connecting the inner and outer rings of the Cartwheel Galaxy are the ones detected by the Webb telescope’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI).
Other spokes show up in visible light, and still others in radio wavelengths. And they’re not the same spokes. They don’t overlap. Whatever’s going on in that galaxy, it’s complicated.
Speaking of complicated, I talked about thermal radiation back in June. Basically, anything warmer than absolute zero glows.
The warmer something is, the more it glows. We call that glow thermal radiation. It’s one sort of electromagnetic radiation.
As something gets hotter, its thermal radiation wavelengths get shorter. Well, the peak wavelengths do, at any rate.
When stuff is warmer than 977 °F, 525 °C, we can see the glow, because that’s when the glow is in wavelengths short enough for our eyes can detect.
The part of the electromagnetic spectrum — I’m going to call it “light” from here in, regardless of wavelength — we can see has wavelengths between 420 and 680 nanometers. Or between 310 and 1,050 nanometers. That’s under ideal conditions and for children and young adults.
Our name for light between about 700 nanometers and one millimeter is infrared light.
Longer than that, it’s microwaves (from extremely to ultra high frequency), and radio waves (from very high to extremely low frequency).
But those are just convenient labels we use. It’s all light. So are ultraviolet rays, X-rays and gamma rays: all of which have wavelengths shorter than visible light.2
Mid-Infrared: Cool
(From NASA, ESA, CSA, STScI; used w/o permission.)
(The Cartwheel galaxy group, Image from Webb’s Mid-Infrared Instrument (MIRI).
(James Webb Space Telescope image released by NASA (August 2, 2022))
That Webb image of the Cartwheel galaxy group, the one at the start of this post, isn’t what the galaxies look like.
Or would look like, if we were close enough and if our eyes collected enough light to register such definite colors.
That’s because this post’s first image combines what the Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) saw.
NIRCam sees in the near infrared: wavelengths between 600 and 5,000 nanometers.
NIRCam has to be cold to see those wavelengths — I’m going to call them “colors,” since that’s our name for different wavelengths of visible light. It’s designed to operate at 37 Kelvin, about minus 400 degrees Fahrenheit.
MIRI is a camera and a spectrograph that sees light with wavelengths of 4,900 to 28,600 nanometers, so it needs to be colder. Much colder: around 7 Kelvin.3
So neither the NIRCam and MIRI combined image nor the only-MIRI image show what the Cartwheel Galaxy really looks like.
Or maybe what it literally looks like would be a better way of putting the idea.
Astrophotos: More Than Pretty Pictures
(From NASA, ESA, CSA, STScI; used w/o permission.)
(NGC 3324 in Carina Nebula, Image from Webb’s NIRCam.)
(James Webb Space Telescope image released by NASA (July 12, 2022))
Now, there are folks who apparently feel that color images of astronomical subjects aren’t serious science.
I suspect that the ‘color images aren’t serious science’ demographic overlaps folks who think serious anything isn’t ‘real’ science, poetry or whatever unless discussions of it are as dull as dishwater.
I’ll grant that the James Webb Space Telescope team probably picked non-ugly colors as stand-ins for their infrared analogs.
Partly, I suspect, because attractive images help non-scientists get interested in what the scientists are doing.
Partly because they’ll be looking at the ‘pretty pictures’ more than most folks.
And partly because it’s a whole lot easier to see how stuff that’s glowing in a particular way is distributed in a galaxy, a nebula or whatever if it’s a particular color.4
The way I see it, any subject — science, history, sports, whatever — can be presented as reams of statistics without obvious context, or as easily-seen patterns of data. And if the data’s attractively presented, then that’s a bonus.
The Cartwheel Galaxy Group as We Might See It
(From NASA, ESA, K. Borne (STScI); used w/o permission.)
(The Cartwheel galaxy group, colors as we would see them, from Hubble space telescope. (released May 15, 2007)
Even that ‘true color’ astrophoto, made using images from the Hubble Space Telescope, isn’t a color photo like the ones my camera takes.
Scientists combined an I-band (814 namometer) and a B-band (450 nanometer) image, then balanced the red and blue composite to approximate what our eyes would see.
What our eyes would see, that is, if they were huge, collecting enough light for the cone cells in our eye’s retina. One of these days, I may talk about astrophotography, human vision, surface brightness and all that.5
But not today.
A Famous Quartet-Plus-One
(From NASA, ESA, CSA, and STScI; used w/o permission.)
(Stephan’s Quintet.)
(James Webb Space Telescope image released by NASA (July 12, 2022))
Édouard Stephan spotted Stephan’s Quintet in 1877. It’s in the constellation Pegasus and is the first compact galaxy group discovered.
It’s also not really a quintet. Four of the five galaxies are part of a group, and are merging with each other. The fifth member, NGC 7320, is much closer to us: very roughly 39,000,000 light-years, or maybe 40,000,000 light-years. Give or take.
The four associated galaxies are between 210,000,000 and 340,000,000 light-years out.
Like the Cartwheel image, this picture combines images from the Webb telescope’s NIRCam and MIRI.
Another fun fact: Stephan’s Quintet, which is really a quartet-plus-one, is also called the Hickson Compact Group 92 or HCG 92.6
Fun? Details like that are fun for me, at any rate.
There’s a mess more to say about those galaxies, but that’s a set of facts and analysis I’ll leave for another time. Except for the Stephen’s Quintet and a 1947 film.
Featured in “It’s a Wonderful Life”
(From Liberty Films, Hubble and Chandra Space Telescopes, Alfred Charles, Tony Rice, WRAL/Capitol Broadcasting Company; used w/o permission.)
(Stephan’s Quintet, “It’s a Wonderful Life” and the Hubble & Chandra Space Telescopes)
Stephan’s Quintet, three fifths of it at any rate, may be the most-televised galaxy group.
A made-for-the-movies version of the galaxy group appeared in “It’s a Wonderful Life.”
The RKO/Liberty Films feature bothered critics, cost the studio something like a half-million dollars — that’s 1947 dollars, mind — and was flagged as a possible communist plot by the FBI.
I am not making that last bit up. Seems that some zealous official wrote a memo:
“With regard to the picture ‘It’s a Wonderful Life’, [redacted] stated in substance that the film represented rather obvious attempts to discredit bankers by casting Lionel Barrymore as a ‘scrooge-type’ so that he would be the most hated man in the picture. This, according to these sources, is a common trick used by Communists. [In] addition, [redacted] stated that, in his opinion, this picture deliberately maligned the upper class, attempting to show the people who had money were mean and despicable characters.”
(FBI memo (May 26, 1947) quoted by Will Chen, Johnny Goodtimes, Kat Eschner; via Wikipedia)
As I’ve said before, and probably will again, I do not miss ‘the good old days.’ I mentioned communist plots and climate change last week, and that’s another topic.
Anyway, “It’s a Wonderful Life” collected dust until the 1976 Christmas season. It’s been a holiday staple ever since.7
And that’s all I have for this week.
Apart, that is, from notes and resources that didn’t make it into this post. Which I’ve saved for future use. Assuming I remember where I put them, and assuming that scientists analyze data from the James Webb Space Telescope and publish what they’ve learned.
The latter is, I think, a safe assumption.
Now, links to posts that are about astronomy and galaxies; and one that’s not:
- “Green Sahara, Environmental and Climate News“
(July 30, 2022) - “Trace Signals From an Alien Civilization: Not So FAST?“
(June 25, 2022) - “Exoplanets, Iron, Evolution and Strange Geochemistry“
(January 22, 2022) - “A Star by Any Other Name, and a Galilean Interlude“
(November 13, 2021) - “Supernova Requiem: Reruns From a Gravity Lens“
(September 18, 2021)
1 Introducing the Cartwheel galaxy group:
- Wikipedia
- Cartwheel Galaxy
- European Southern Observatory Catalog (in which the Cartwheel Galaxy is ESO 350-40)
- Fritz Zwicky
- James Jeans
- Principal Galaxies Catalogue (in which the Cartwheel Galaxy is PGC 2248)
- Cartwheel Galaxy
SIMBAD Astronomical Database – CDS (Strasbourg) - “The Cartwheel Galaxy — Introduction“
Classroom-Ready Activities, Chandra X-Ray Observatory, Smithsonian - “Collisional Ring Galaxies,” Introduction
P.N. Appleton, Curtis Struck-Marcell; Erwin W. Fick Observatory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa;
Published in Fundamentals of Cosmic Physics (Vol. 16, pp. 111-220, 1996) via NASA/IPAC Extragalactic Database, Caltech - Jeans instability
Overview, Oxford Reference - “Jeans Instability and Gravitational Collapse“
Physics 431, Steve McMillan’s course pages; Department of Physics; Drexel University College of Arts and Sciences - “Webb Captures Stellar Gymnastics in The Cartwheel Galaxy“
Press release, Webb Telescope, Goddard Spaceflight Center, NASA (August 2, 2022) - “Cartwheel Galaxy Region“
Hubble, European Space Agency (last updated: September 1, 2019)
2 Wavelengths, temperatures and detecting glowing stuff:
- Wikipedia
- Webb Space Telescope
3 More about astronomy and detecting glowing stuff:
- Wikipedia
- Webb Space Telescope
4 More than you may need or want to know about:
- Wikipedia
- Webb Space Telescope
- “NASA’s Webb Reveals Cosmic Cliffs, Glittering Landscape of Star Birth,” press release (July 12, 2022 )
- “What is meant by ‘false color’?“
StarChild Question of the Month for April 2000, NASA - “The Scientific Value of ‘Pretty Pictures’“
Richard S. Wright Jr., Sky and Telescope (August 18, 2020)
- Wikipedia
- Wide Field and Planetary Camera 2 (Hubble Space Telescope)
- “Cartwheel Galaxy
Image associated with press release, Hubblesite (May 15, 2007) - “Collisional Ring Galaxies,” Introduction; P.N. Appleton, Curtis Struck-Marcell; Erwin W. Fick Observatory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa; Published in Fundamentals of Cosmic Physics (Vol. 16, pp. 111-220, 1996) via NASA/IPAC Extragalactic Database, Caltech
- “How Does My Eye Compare to the Telescope?“
“From the Ground Up!,” Eye v. Telescope v.1 -8, Harvard-Smithsonian Center for Astrophysics - “How We & Telescopes See“
Fort Worth Astronomical Society
- Wikipedia
7 Galaxies, a movie and a little history:
- Wikipedia
- “Classic film ‘It’s a Wonderful Life’ features angelic galaxies“
Tony Rice, WRAL (December 22, 2019, updated December 18, 2021)
