Galaxies, Gravity and a Hot Terrestrial Planet

NASA, ESA, CSA, J. Lee (NOIRLab)'s image (processed by Alyssa Pagan (STScI)): galaxy NGC 1433, high resolution image from James Webb Space Telescope at 21 microns (blue), 11.3 microns (green), and 7.7 microns (red). (released February 16, 2023)
NGC 1433, image from JWST, at 21 microns (m.) (blue), 11.3 m. (green), and 7.7 m. (red). (February 2023)

NASA’s Webb Reveals Intricate Networks of Gas and Dust in Nearby Galaxies
Laura Betz, NASA’s Goddard Space Flight Center, Greenbelt, Maryland; Christine Pulliam, Hannah Braun, Space Telescope Science Institute, Baltimore, Maryland; Editor Jamie Adkins (February 16, 2023)

“Researchers using NASA’s James Webb Space Telescope are getting their first look at star formation, gas, and dust in nearby galaxies with unprecedented resolution at infrared wavelengths….”

“…’The clarity with which we are seeing the fine structure certainly caught us by surprise,’ said team member David Thilker of Johns Hopkins University in Baltimore, Maryland.

“‘We are directly seeing how the energy from the formation of young stars affects the gas around them, and it’s just remarkable,’ said team member Erik Rosolowsky of the University of Alberta, Canada….”

The Webb data had already been used in 21 research papers, back in February.

I’d prefer looking up a few of them, picking out one that sounded interesting, and talking about it. But I’ve had a distracted week. So today I’ll focus on some really cool pictures from the JWST/Webb telescope. Mostly.

(I gave the pictures links, so clicking on them takes you to the articles or resources I found them in.)

NGC 1433: Hubble Space Telescope’s View

 ESA/Hubble and NASA (D. Calzetti (UMass), the LEGUS (Legacy ExtraGalactic UV Survey) Team)'s image: NGC 1433, mixing ultraviolet, visible, and infrared light. (released July 7, 2014)
NGC 1433, image from Hubble Space Telescope, a mix of ultraviolet, visible and infrared light. (July 2014)

NASA, ESA, CSA, J. Lee (NOIRLab)'s image (processed by Alyssa Pagan (STScI)): NGC 1433, James Webb Space Telescope. (released February 16, 2023)Since the Hubble Space Telescope image (above) shows NGC 1433 in ultraviolet, visible and infrared light, and the Webb image (right) shows three colors of infrared, this isn’t an apples-to-apples comparison.

But it’s not apples-to-oranges, either. Maybe oranges-to-tangerines.

The point is that the Webb telescope shows NGC 1433 in somewhat higher resolution, and at different wavelengths; which lets scientists see new details. NGC 1433 is a bared spiral galaxy with a bright nucleus, the sort astronomers call a Seyfert galaxy.1

One more excerpt from that February 16, 2023 piece:

“…Webb’s powerful infrared capabilities can pierce through the dust to connect the missing puzzle pieces.

“For example, specific wavelengths observable by MIRI (7.7 and 11.3 microns) and Webb’s Near-Infrared Camera (3.3 microns) are sensitive to emission from polycyclic aromatic hydrocarbons, which play a critical role in the formation of stars and planets. These molecules were detected by Webb in the first observations by the PHANGS program.

“Studying these interactions at the finest scale can help provide insights into the larger picture of how galaxies have evolved over time….”
(“NASA’s Webb Reveals Intricate Networks of Gas and Dust in Nearby Galaxies
NASA’s Goddard Space Flight Center, Space Telescope Science Institute; Baltimore, Maryland (February 16, 2023))

Abell 2744, ‘Pandora’s Cluster’: Closer Look, New Details of Distant Galaxies

NASA, ESA, CSA, I. Labbe (Swinburne University of Technology), R. Bezanson (University of Pittsburgh)'s image (processed by Alyssa Pagan (STScI)): Abell 2744 ('Pandora's Cluster') from James Webb Space Telescope NIRCam; deep field image with the megacluster's gravitational lens magnifying distant galaxies. (released February 15, 2023)
‘Pandora’s Cluster’, Abell 2744, Hubble and JWST imagery.

NASA’s Webb Uncovers New Details in Pandora’s Cluster
Laura Betz, NASA’s Goddard Space Flight Center, Greenbelt, Maryland; Leah Ramsey, Christine Pulliam, Space Telescope Science Institute, Baltimore, Maryland; Editor Jamie Adkins (February 15, 2023)

“Astronomers have revealed the latest deep field image from NASA’s James Webb Space Telescope, featuring never-before-seen details in a region of space known as Pandora’s Cluster (Abell 2744). Webb’s view displays three clusters of galaxies – already massive – coming together to form a megacluster. The combined mass of the galaxy clusters creates a powerful gravitational lens, a natural magnification effect of gravity, allowing much more distant galaxies in the early universe to be observed by using the cluster like a magnifying glass….

“…’Pandora’s Cluster, as imaged by Webb, shows us a stronger, wider, deeper, better lens than we have ever seen before,’ [Swinburne University of Technology’s astronomer Ivo] Labbe said. ‘My first reaction to the image was that it was so beautiful, it looked like a galaxy formation simulation. We had to remind ourselves that this was real data, and we are working in a new era of astronomy now.’…”
[emphasis mine]

Abell 2744, nicknamed Pandora’s Cluster, is about 4,000,000,000 light-years out in the constellation Sculptor.

Scientists figure Abell 2744 happened when several smaller clusters collided. Its gas is so hot, it glows in the X-ray end of the spectrum. It’s also got a radio halo: all of which makes Abell 2744 something of a one-stop science resource.

About Abell 2744’s ‘Pandora’s Cluster’ nickname:

“…’The ancient myth of Pandora is about human curiosity and discoveries that delineate the past from the future, which I think is a fitting connection to the new realms of the universe Webb is opening up, including this deep-field image of Pandora’s Cluster,’ said astronomer Rachel Bezanson of the University of Pittsburgh in Pennsylvania, co-principal investigator on the ‘Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization’ (UNCOVER) program to study the region.

‘When the images of Pandora’s Cluster first came in from Webb, we were honestly a little star struck,’ said Bezanson. ‘There was so much detail in the foreground cluster and so many distant lensed galaxies, I found myself getting lost in the image. Webb exceeded our expectations.’ The new view of Pandora’s Cluster stitches four Webb snapshots together into one panoramic image, displaying roughly 50,000 sources of near-infrared light….”
NASA’s Webb Uncovers New Details in Pandora’s Cluster
NASA’s Goddard Space Flight Center, Greenbelt, Space Telescope Science Institute; Baltimore, Maryland (February 15, 2023) [emphasis mine]

Now, about those “distant lensed galaxies”: All that mass in the Abell 2744 cluster bends light around it, magnifying even more distant galaxies.2

Galaxies, Gravity and More Galaxies
NASA, ESA, CSA, I. Labbe (Swinburne University of Technology), R. Bezanson (University of Pittsburgh)'s image (processed by Alyssa Pagan (STScI)): detail of James Webb Space Telescope NIRCam's Abell 2744 ('Pandora's Cluster') image; a gravitational lens magnifying distant galaxies. (February 15, 2023)
‘Pandora’s Cluster’, Abell 2744, Hubble and JWST imagery, detail: distant galaxies in a gravity lens.

This is a detail of the first ‘Pandora’s Cluster’ image: a closer look at the cluster of galaxies to the left of center.

Those streaky images in the upper right are galaxies beyond Abell 2744, magnified and distorted by the galaxy cluster’s gravity. I’m pretty sure about that, at any rate. They look like gravity-lensed-galaxies I’ve seen elsewhere.

Lensed Galaxies: Showing How Gravity Lenses Work
STScI's illustration (NASA Contract NAS5-26555): 'Illustration for gravitational lens. Bending light around a massive object from a distant source. The orange arrows show the apparent position of the background source. The white arrows show the path of the light from the true position of the source.' (July 2000)
Gravity lens illustration: magnified image (orange arrows), path of light from distant object (white arrows).

I’m hoping that “a picture is worth a thousand words”, since I don’t have time to talk about gravity, light, Einstein and cosmic magnifying glasses.3

Earth-Size, But Not Earth 2.0

NASA, ESA, CSA, L. Hustak (STScI), K. Stevenson, J. Lustig-Yaeger, E. May (Johns Hopkins University Applied Physics Laboratory), G. Fu (Johns Hopkins University), S. Moran (University of Arizona)'s illustration: 'A light curve from the NASA/ESA/CSA James Webb Space Telescope’s Near-Infrared Spectrograph (NIRSpec) shows the change in brightness from the LHS 475 star system over time as the planet transited the star on 31 August 2022.' (August 2022)
Transit light curve LHS 475 b, from JWST/Webb Telescope. (August 2022)

LHS 475 b is just like Earth, except for how it’s not.

It’s a terrestrial planet, like our Solar System’s inner four worlds. It orbits LHS 475, a red dwarf star about 40 light-years out, in the constellation Octans.

Octans is one of the dozen-plus constellations mapped and named by Lacaille. I talked about that earlier this month.

LHS 475 is very roughly 1/100th as bright as our star, but LHS 475 b whips around it once every two days. That puts it very close to its sun, so LHS 475 b is hot.

Its equilibrium temperature would be 313 °C, 595 °F; but since it’s almost certainly is tidally locked, with one side always facing its sun, the day side temperature could be around 475 °C; 887 °F.

That’s assuming LHS 475 b doesn’t have an atmosphere. Which is likely enough, considering how hot it is, and how close it is to its sun.

On the other hand, LHS 475 b is almost exactly the size of our planet, 99% Earth’s diameter, and apparently made out of rock and metal.4

LHS 475 b: Methane, No; Carbon Dioxide, Maybe; Or Maybe No Atmosphere At All
NASA, ESA, CSA, Leah Hustak (STScI) SCIENCE: Kevin B. Stevenson (APL), Jacob A. Lustig-Yaeger (APL), Erin M. May (APL), Guangwei Fu (JHU), Sarah E. Moran (University of Arizona)'s illustration: James Webb Space Telescope’s Near-Infrared Spectrograph (NIRSpec) transmission spectrum, made during transit of LHS 475 b. (August 31, 2022)
JWST transmission spectrum of LHS 475 b. (August 31, 2022)

But LHS 475 b definitely is not Earth 2.0. It’s too hot, and may have no atmosphere.

But maybe it does.

Since the planet passes between its sun and us, JWST can measure how light from LHS 475 changes during the planet’s transits.

So far, the data says LHS 475 b doesn’t have a mainly-methane atmosphere. But it might have an atmosphere that’s mostly carbon dioxide. Or no atmosphere at all.

Either way, the planet is emphatically not suitable for life as we know it.

If the no air and tidally locked scenario is right, LHS 45 b’s dayside temperatures are hot enough to melt lead or zinc. At Earth’s sea-level pressure, and that’s another topic.5

Terrestrial, Telluric, Solid, or Rocky: There’s No Place Like Home

NASA/JPL-Caltech/R. Hurt's artist's concept: how rocky, potentially habitable planets might appear. (April 13, 2022)
R. Hurt’s illustration: what potentially habitable planets might look like. (2022)

“Terrestrial planet” reminds me of Star Trek’s “Class M planet”: a world with surface conditions pretty much like southern California. A world like that would be terrestrial, but not all terrestrial planets are habitable.

What is, and isn’t, a terrestrial planet depends partly on who’s talking.

Earth, for example, is a terrestrial planet. So are the inner Solar System’s three other worlds: Mercury, Venus and Mars. All four are mostly metal and silicate rock.

That quartet are, according to the IAU, the International Astronomical Union, the Solar System’s only “terrestrial planets”.

But that’s not the only definition in play.

IUGS, the International Union of Geological Sciences, defines “terrestrial planet” so that Earth’s moon, Jupiter’s Io and maybe Europa, are also “terrestrial”. Along with asteroids Pallas and Vesta.

Other monikers for terrestrial planet are telluric planet, solid planet and rocky planet.

Natalie Batalha's and Wendy Stenzel's chart of exoplanet populations found with Kepler data. (2017) (NASA and Ames Research Center)I’m not sure whether theoretical planet types like carbon and coreless planets would count as “terrestrial”.

The words telluric and terrestrial come from Latin words for Earth, Terra and Tellus; and I’m wandering off-topic.

Over the last few decades, we’ve been learning a very great deal about planets and planetary systems. So it’s no wonder that scientists haven’t settled on names and definitions for all the newly-discovered varieties.6

We still haven’t spotted anything quite like Star Trek’s “Class M planet”, or made contact with folks whose ancestors are from another world.

But like I said: we’re learning a great deal about how planets and stars form. And that helps make this a very exciting era. For me, that is:

1 Galaxies and telescopes:

2 Abell 2744 and a little science:

3 Looking deeper into this universe:

4 Tiny sun, Earth-size planet:

5 Science stuff:

6 Several sorts of worlds, two science associations:

About Brian H. Gill

I was born in 1951. I'm a husband, father and grandfather. One of the kids graduated from college in December, 2008, and is helping her husband run businesses and raise my granddaughter; another is a cartoonist and artist; #3 daughter is a writer; my son is developing a digital game with #3 and #1 daughters. I'm also a writer and artist.
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