ASTRONOMY

ASTRONOMY RESOURCES

Astronomy.com: https://astronomy.com/news

Phys.org: https://phys.org/space-news/astronomy

Space.com: https://www.space.com/news

Science Daily: https://www.sciencedaily.com/news/space_time/astronomy

Sky and Telescope: https://skyandtelescope.org/astronomy-news

NASA Exoplanet Exploration News: https://exoplanets.nasa.gov/news

IN THE SKY THIS WEEK

ASTROTOURISM IS A THING! And not just for Total Solar Eclipses! Over 80% of Americans live in areas where light pollution is so severe that one can never see the Milky Way; they see only the brightest stars and planets on a good night. Astronomical communities and Dark Sky zones are springing up in places where one can actually see a dark sky. Many U.S. National Parks and Monuments, at least those in favorable locations, have Dark Sky programming and events!

NOVA Watch: No, I’m not promoting the really good PBS series, I’m talking about T Coronae Borealis, a recurring nova. It’s usually about magnitude +10, not exactly a target for most backyard astronomers. However, every 80 years or so, it goes nova, becoming as bright as Alphecca, the brightest star in the Northern Crown (Corona Borealis). The last time it blew was in 1946, and its starting to show the same signs it did back then before it brightened.

I would suggest you become familiar with the look of this particular constellation so you can see the change for yourself when it happens. You can find out more about it at: https://skyandtelescope.org/astronomy-news/observing-news/this-weeks-sky-at-a-glance-june-7-16 . There is a link within to a 2016 Sky & Telescope article by Bob King that shows you how to find T CrB at its normal brightness.

But wait, there’s more! There is a supernova right now in galaxy NGC 3524, in Leo. It’s shining as brightly as the entire galaxy it’s in! Those of you with access to a relatively-good telescope – check it out!

Sun: The Sun has an ~11-year cycle of sunspot activity. The last minimum period was in late 2020; the next maximum will be in mid-2025. NOAA’s 30-Minute Aurora Forecast: https://www.swpc.noaa.gov/products/aurora-30-minute-forecast.

THE PLANETS THIS WEEK

Moon: The Moon reaches First Quarter at 1:18 AM EDT on Friday, June 14.

The Planet Parade is Over, but you can still easily see Saturn and Mars in the morning sky. Neptune, too, if you have a good telescope and know just where to look. Saturn shines at +1.2, in Aquarius, and Mars is about the same brightness, a ways to Saturn’s lower-left (use your fist at arm’s length and go four “fists” from Saturn to get to Mars. Mercury, Venus, Jupiter, and Uranus are too close to the Sun in the sky to be seen.

COMETS

Sky & Telescope’s “Best Comets in 2024:” https://skyandtelescope.org/astronomy-news/the-best-comets-in-2024

Comets (presently brighter than +10): There are presently only three.

Comet 12P/Pons-Brooks, discovered in 1812, has also arrived in its 70-year period. It’s fading quickly (now fainter than +6.7) but it is no longer visible in the northern hemisphere (it’s now in Lepus). For more information, see here and here. This particular comet has been in a number of Science-phobic social media posts because of an unfortunate asymmetric release of a pulse of gas and dust, briefly forming a twin tail that some have taken to be the (actual) Devil’s horns or that the comet is a giant version of the Millenium Falcon. Comets always seem to get a bad rap! The orientation of its orbit causes it to appear to have two tails, one following and one ahead of it, much like Comet Arend-Roland back in 1057! Here’s some more real information about it: https://phys.org/news/2024-03-12ppons-brooks-devil-comet.html.

Comet 13P/Olbers has returned to perihelion, on its 68-year orbit. Not paradoxically, it may get as bright as +6. It’s presently is between Capella and Castor, shining at ~+8.3. You’ll need a flat WNW horizon and good optics to see it in the evening’s late twilight sky.

Recently-discovered Comet C/2023 A3 (Tsuchinshan-ATLAS) is on a trajectory that will bring it near enough to Earth in October, 2024, for it to be potentially an unaided-eye object. It’s already at ~+10, lying at the edge of the “bowl” of Virgo, north of Crater. It will brighten quickly in the coming weeks. CHECK OUT the latest info (5/12) on this newcomer and a sighting map, see: https://skyandtelescope.org/observing/celestial-objects-to-watch/comets/comet-tsuchinshan-atlas-brightens-grows-a-tail! There is some possibility it could be really bright, see: https://phys.org/news/2023-03-astronomers-comet-brighter-stars-year.html and http://www.aerith.net/comet/catalog/2023A3/2023A3.html. Let’s be optimistic (but I remember not seeing Kohoutek…).

Looking much farther ahead: Hailey’s Comet reached aphelion recently. It’s now swinging back toward the Sun, reaching perihelion on June 28, 2061. I hope to see you there, wait, who am I kidding?

For info on comets currently visible, see: http://www.aerith.net/comet/weekly/current.html.

SATELLITES THIS WEEK

International Space Station and Key Satellites This Week

There are no visible overpasses of the ISS this week for those of you in the DC area.

There are no overpasses of the ISS this week for those of you in the Colorado Springs area.

There are no overpasses of the HST during the next week for those of you in the DC area. 

There are no overpasses of the HST during the next week for those of you in the Colorado Springs area, but it is unfavorable.

To find out about satellite overpasses in your area, see https://heavens-above.com (set your own location in the upper-right corner).

ASTRONOMY NEWS

“Recent” Milky Way Collision: Astronomers have long believed that collisions between galaxies is fairly common, and that our own Milky Way has not been exempt. The Magellanic Clouds and perhaps even globular clusters are remnants of our collisional past, some 8-11 billion years ago. Recent observations and computer modeling, however, suggests that a collision has occurred more recently, on the order of three billion years ago. A team from RPI used data from ESA’s Gaia satellite, which is mapping a billion stars across the Milky Way, noting their motion, luminosity, and composition. Those data were used in creating computer modeling of how those stars may have acquired that motion.

As you might imagine, an inter-galactic collision and their combined and shifting gravity, would affect the movement of individual stars significantly, creating a wavy structure not unlike ripples in a pond. Such rhythmic stellar motions would tend to dampen with time, giving at least a crude estimation of the time since the original disturbance. When the Gaia data are put in the model, there is more wavy structure than would be expected if the disturbing collision was as old as thought, the collision had to have been more recent. For an announcement and summary of this research, see: https://news.rpi.edu/2024/06/06/rensselaer-researchers-upend-theory-about-formation-milky-way-galaxy.

We Are Star Stuff: Prevailing thought about post-Big Bang neucleosynthesis holds that elements heavier than helium were created by fusion process within stars, at least up to iron. Fusion reactions involving iron and above are endothermic, requiring a lot of energy to produce. The only logical energy source for those reactions comes when that particular star goes super-nova. OK, but why do we see evidence of a higher quantity of heavier-than-iron elements than we would expect from supernovae?

In the last decade, we have learned more about another mechanism that may be capable of creating heavy elements, via the detection of gamma-ray bursts. Two types of GRBs have been observed, “long” and “short.” Long GRBs are likely caused by the death of massive, fast-rotating stars, where the rotation ejects material into narrow, fast-moving jets of gamma rays. Short GRBs are thought to be the flash formed by the collision of two neutron stars. Such a collision is capable of not only spewing gamma rays, the resulting explosion can actually send detectable gravitational waves in our direction. The energy from a GRB could conceivably be capable of fusing heavier elements. One such event has been observed, in August, 2017. Earth-bound gravity detectors detected the signal of an impending collision of neutron stars, and a few seconds later, a significant GRB was detected from the same spot in the sky. The spot was monitored by a number of instruments, and within a few weeks revealed that a “kilonova” explosion, big but smaller than a full-blown supernova. A large amount of heavy elements was observed, too.

There is a problem with both hypotheses. Neutron star-neutron star collisions are very rare, and even if each produced heavy elements, there aren’t enough such collisions to produce the quantities of heavy elements we observe.

What about long GRBs? On October 9, 2022, the biggest long GRB ever seen occurred. Detailed observations of the site of the GRB’s origin showed no concentration of heavy elements, so long GRBs cannot be the energy source for the creation of heavy elements, either.

Back to the Hypothesis Drawing Board!

For more on this issue, see: https://phys.org/news/2024-05-universe-biggest-explosions-elements-mystery.html.

Hunting for the “First Stars” Immediately after the Big Bang, there were large amounts of hydrogen and helium suffusing Space. The first stars, so-called “Population III,” began forming almost immediately, really big ones. Intense fusion processes deep within them formed many of the heavier-than-helium atoms around us. The initial and final chemistry of these behemoths would reveal much about the earliest days of the Universe. But finding them is difficult. Along with the Population III stars, a large number of black holes formed, too. Astronomers hypothesize that when a Pop III star gets close to a black hole, it suffers a “tidal disruption event,” meaning it is torn apart by the black hole’s intense gravity, which produces an incredibly-bright flare. Since the distance to the disruption site is huge, the light from it is strongly red-shifted into the IR, and the spectral lines seen give clues as to the composition the disrupted star. For a summary of this work, see here; for the paper in The Astrophysical Journal Letters, see here.

Fingerprints of Iron: The Japanese XRISM satellite observatory has acquired X-ray spectral data from the area around active-center galaxy NGC 4151, 43 million light-years away. The galaxy has a giant black hole at its center, 20 million times more massive than the Sun. Gas and dust falling into the black hole releases huge amounts of energy, much of it at X-ray wavelengths, which XRISM was designed for. The X-rays cause the inrushing material to fluoresce, and the wavelengths of the resulting spectral lines reveal the chemistry of the gas. One such wavelength indicates the presence of iron. XRISM website: https://www.xrism.jaxa.jp/en; summary of study: https://www.sciencedaily.com/releases/2024/05/240508113126.htm; NASA: https://science.nasa.gov/missions/xrism/nasa-jaxa-xrism-spots-iron-fingerprints-in-nearby-active-galaxy.

Hungry White Dwarfs are Sloppy Eaters: The vast majority of stars in our galaxy either are white dwarfs, or will end up as one near the end of their “lives.” Spectral analysis of the light from many of them shows the presence of elements heavier than should be on their surfaces. Such “pollution” is most likely to come from the accretion of planetesimals rich in “metals” (any element heavier than helium to astronomers). Detailed computer simulations of material in orbit around a forming white dwarf show that such accretion will likely continue for an extended period. For a summary of this work, see https://phys.org/news/2024-05-hungry-white-dwarfs-puzzle-stellar.html.

Big Bad Black Holes Blow Bigly: Data from the JWST lead to a hypothesis that the formation of super-massive black holes in the earliest giant galaxies shut off the formation of new stars within them. The data show that the galactic version of “solar wind” is made up mostly of neutral gas, not detectable before the JWST. The neutral gas was the fuel for new star creation; when much of it was blown out of the galaxy, star formation slowed/stopped. For a summary of this work, see here; for the abstract of the paper in Nature, see here.

Funding is a Problem in the Next Two Stories

First: Chandra X-ray Observatory: “NASA's budget for 2025 and projections forward foresee a steep reduction in funding for Chandra. This change would also slash support for research projects in X-ray astronomy, especially in the U.S.” While it is true that Chandra’s instruments are showing their age a bit, the satellite has a lot more operational life left; if the present budget cuts hold then Chandra will begin a three-year slowdown/shutdown. For more, see: https://skyandtelescope.org/astronomy-news/an-early-end-for-the-chandra-x-ray-observatory.

[The JWST and M-1: The Crab Nebula in Taurus is a favorite of backyard astronomers. It was one of the first supernova remnants discovered and identified as such. The Anasazi at Chaco Canyon were so impressed by the 1054 CE supernova that made it that they recorded the event in a petroglyph (still extant but very highly protected!). The HST, not long after its deployment, returned a beautiful visible-light photo of it in 2015. Now it’s JWST’s turn, and it sent back an infrared image of the Crab that is allowing astronomers to identify different supernova-related elements and learn more about the supernova that created it. For more info, see: https://www.jpl.nasa.gov/news/the-crab-nebula-seen-in-new-light-by-nasas-webb.

UPDATE: There is an image of M-1 in the Chandra budget item above that combines visible-light data from the HST, IR data from Spitzer, and X-ray data from Chandra; it’s quite spectacular! See for yourself at: https://skyandtelescope.org/astronomy-news/an-early-end-for-the-chandra-x-ray-observatory.]

Second: Bad News for Two Observatories: The National Science Board is a panel of scientists that oversees the National Science Foundation and its funding for large-scale science projects. They met on February 22, and among other things, decided to cap NSF’s support for its Extremely Large Telescope Program at $1.6B (not to be confused with the European Southern Observatory’s Extremely Large Telescope now building on Chile’s Cerro Amazones). The cap will prevent NSF from fully-funding both the Giant Magellan Telescope in Chile and the Thirty Meter Telescope in Hawaii as originally planned, and the NSB is requiring NSF to make a tough decision on the matter by May. 

Both affected telescopes are presently under construction and have already received considerable funding. They joined forces in 2018, offering NSF an opportunity for American astronomers to have access to coverage of the entire sky in exchange for public support. The National Academy of Science’s 2020 Decadal Survey in Astrophysics prioritized the pair the highest among other ground-based astronomy projects, and the NSF approved preliminary design reviews early last year. The mirrors for the GMT have been finished, and the observatory site for them has been prepared. The TMT is less far along, in part due to opposition by native Hawaiians to another, larger, dome atop Mauna Kea. The TMT has one advantage, and that its location will provide coverage of the entire sky, if data are shared with ESO’s ELT. That’s a big “if.”

Telescopes of the size now under construction cost more than the NSF is used to. The GMT has a $2.54B price tag, of which only $850M has been pledged by other project sponsors. The TMT is even more expensive, $3.6B, of which about $2B has been pledged by its partners. Funding both as much as NSF can afford risks loss/delays in both, and would consume more than three-quarters of the NSF telescope funding program, which has many other responsibilities. Funding only one wastes money already spent on the other. For more on this dilemma, see: https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes.

The telescopes in question are really huge, on the order of the size of a tennis court. If you want to see a good comparison of their sizes relative to other telescopes (and familiar objects to scale), and find out more about astronomy in Chile, see: https://www.airandspacethisweek.com/assets/pdfs/20240122%20Astronomy%20in%20Chile.pdf.

UPDATE: I came across a March 7 analysis of the NSF telescope funding situation on the “Big Think” website a few days ago. The authors demonstrate that while the need to make the reduction is arguably due to the lack of Congressional support is understandable, many of the reasons put forth to justify the funding reduction are not accurate. The National Board’s assessment of the need for both telescopes is still sound. As the BT authors point out, “Once you stop investing in something important to your nation, that field almost never recovers in that country,” and cite the diminished role for the U.S. in high-energy particle physics research due to the abandonment of the Superconducting upper Collider a few decades ago. It’s a thought-provoking piece; see it for yourself at: https://bigthink.com/starts-with-a-bang/future-astronomy-dimmed-by-half.

But Some Good News, Too, from Chile: Phys.org recently posted a piece about the Vera Rubin Observatory and how it will help astronomers find “weird and wonderful things happening in the Solar System.” There’s a lot of info about the VRO, its Simonyi Telescope, and giant camera, and the piece is built around a recent preprint paper in The Astronomical Journal. The summary makes for interesting reading; see here: https://phys.org/news/2024-01-vera-rubin-weird-solar.html and the AJ paper is accessible here: https://arxiv.org/abs/2401.08763.

More: Another Phys.org item points out the value of the VRO’s ability to image the entire available night-time sky every few days, allowing a search for all sorts of transient objects, either those changing rapidly in brightness, or those changing in location. The latter could include “InterStellar Objects” (ISOs), such as the surprise visits by Oumuamua and Borisov, and many more Near Earth Objects. Some researchers predict as many as 70 new ISOs could be discovered annually when VRO comes on line. This article gives a lot of food for thought, and will likely appeal to the general public. See it at: https://phys.org/news/2024-02-vera-rubin-keen-eye-solar.html.

Still More: Score one for the ALMA radio telescope complex in Chile! Cerro Tololo, the VRO, et. al. are not the only observatories making news in the Andes. Quasars are compact yet extremely energetic objects, where a super-massive black hole in a galactic center generates enormous amounts of energy. They are extremely distant and formed very early after the Big Bang. Astronomical models of quasars predict that they would eject large quantities of molecular gases, the “fuel” for star formation. If the ejection rate is too high, the galaxies containing the quasar have fewer new stars forming that would be the case if all of the ejected gases were incorporated into star formation. ALMA data provide observational evidence for gas outflow; additional work is being done to determine how effective star formation is in utilizing it. For a summary of this research, see here; for the paper in The Astrophysical Journal, see here.

More ALMA: Recent observations of galaxy NGC 253 with the ALMA radio telescope array has revealed the presence of over 100 different molecule species. NGC 253, in Sculptor, is ~10,000 light-years distant, and has more vigorous star formation than is present in our Milky Way. The 100 different molecules detected there is more than double the number of molecular species have been seen in any other galaxy. For more info, see: https://phys.org/news/2024-03-alma-molecular-signposts-starburst-galaxy.html.

Follow up to the Astronomy in Chile Item of the Week: The June, 2024, issue of Sky & Telescope magazine has two major articles about astronomy in Chile. One is about Walter Baade, who is the namesake for one of the Twin Magellan Telescopes at Las Campanas Observatory. The other is about the Vera Rubin Observatory and its Simonyi Telescope atop Cerro Pachón. Baade earned the prestigious Bruce Medal in 1955 for his work on supernovae and how they could produce cosmic rays and neutron stars; the article in S&T is on pages 28-33. The Simonyi Telescope is not the largest in Chile by any means, but it will be paired with the Legacy Survey of Space and Time (LSST) camera, whose 25-inch diameter focal plane is covered by 189 CCDs of 16 million pixels each! It’s by far the largest digital camera ever built, and will image of the entire sky visible to it, at high resolution, every week. The data will be made available to anyone who wants to use it, enabling a remarkable transformation in how astronomy will be done in the future. For more about it, see pages 34-40.

Is ”Dark Matter” Real? An Opposing View has been published by a professor at the University of Ottawa, who used a combination of ideas: Forces of nature decline over cosmic time and light loses energy as it travels long distances. There is some consistency between these ideas and observations, but the ramifications of this model are huge (red shifts are not due to distance but rather “tired light.” For a summary of this idea, see: https://www.sciencedaily.com/releases/2024/03/240315160911.htm; for the paper in The Astrophysical Journal, see: https://iopscience.iop.org/article/10.3847/1538-4357/ad1bc6.

What About “Dark Energy?” Astronomers measured the rate of the Universe’s expansion, and found that the rate of expansion is increasing. The concept of “Dark Energy” somehow being responsible was put forward as an explanation. But is “Dark Energy” a real thing? Could the increasing rate of expansion be in error? Well, maybe. For a summary of the questions being raised about dark energy, see: https://www.sciencedaily.com/releases/2024/03/240311145812.htm; for the paper in The Astrophysical Journal upon which the summary is based, see: https://iopscience.iop.org/article/10.3847/2041-8213/ad1ddd. Curiouser and curiouser!

Hydrogen and Black Holes at the Gates of Dawn (of the Universe): After the Big Bang, the expanding Universe was filled with disorganized mostly-hydrogen gas, the so-called “Dark Ages” of the Universe. Gravity organized the gas into clumps that would eventually become the earliest stars. Their light could not travel far, there was too much hydrogen in the way. But that early light ionized some of the hydrogen, making the star-formation process speed up, the so-called “Epoch of Reionization.” As stars continued to form, the organized into galaxies, and the more stars that formed within them, the less light-blocking hydrogen was present, and the more the starlight could ionize hydrogen in inter-galactic Space. The question has been, were those early galaxies gigantic (with massive black holes), but few, or were they smaller, but more numerous.

Recent clues have been found in JWST data from a very distant, very large group of galaxies called Pandora’s Cluster. Their collective gravity serves as a lens (see Item) to look at galaxies even farther away (younger). The data show that there were a lot of smaller galaxies each producing more ionizing light than expected. 

But black holes were certainly partially responsible for the Epoch, as related here. Astronomers using JWST data have learned that black holes were present very soon (< 50M years) after the Big Bang, and that their presence may have accelerated the birth of new stars and galaxies during that period. Further, the oldest black hole yet discovered dates from ~300M years after the Big Bang. It’s really big, on the order of a few million solar masses, posing the question: Was it born big, or has it been eating its galaxy at a much higher rate than previously thought possible? For more on the accelerated star formation part, see here, and for the paper the summary is based upon, see here. For more on the biggest black hole, see here, and for the abstract of the paper the summary is based upon, see here. [And yes, I was channeling my inner Pink Floyd for the title of this bit. Most cool of you to notice!]

The Eddington Limit: Sounds like a great name for a band of musical nerds. Sir Arthur Eddington will likely be in the news in the coming months, primarily for his observations of a total eclipse of the Sun in 1919 that led to the general acceptance of Einstein’s Theory of Special Relativity. But while the eclipse led to Eddington’s knighthood, he is also known for something else, the maximum luminosity a star can achieve when it is in hydrostatic equilibrium, where the radiation pressure from within balances gravitational forces. I ran into the Eddington Limit in a recent article here, and intrigued by mention of Sir Arthur’s name in another context, I dug deeper, finding the astronomy course PowerPoint here. The math therein looks scary at first, but it really isn’t that bad, and it’s nice to know that a black hole’s appetite does have an upper limit!And when a star’s luminosity spikes, Super-Eddington conditions prevail, where radiation pressure can greatly exceed gravity and ka-boom! My new friend in the Southern Sky, Eta Carina, may be an example.

Grand Theft Planet (?): Big guys take stuff from little guys; it’s a story as old as Humanity. It’s also true in the animal and plant world, and it may well be true in the celestial realm. Large stars, ones that will be Type O or B when they are fully formed, generate a lot of UV radiation in their formative stage, which would drive off most of the gas in their vicinity, inhibiting planet growth, at least larger planets (like Jupiter). A recent study of a large cluster of newly-formed stars showed that at least two large stars have at least one large exoplanet. That prompted computer modeling shows that, at least under some conditions, large stars can steal planets from smaller stars. The modeling showed that large stars can rip exoplanets away from the smaller stars around which they formed, and either capture the exoplanet outright or throw it into interstellar Space where another big star can grab it. For more on this sordid tale of larceny writ large, see: https://eos.org/articles/massive-stars-may-commit-grand-theft-planet.

HST: Nearest Earth-sized Exoplanet: JWST may be getting the lion’s share of astronomical news, but the Hubble Space Telescope is still making important observations! Data from HST of an exoplanet designated LTT 1445Ac, found in data from TESS in 2022, show it to be just slightly larger than Earth, but so close to its red dwarf sun that its surface temperature would have to be on the order of 500 K. It is a three-exoplanet system, only 22 light-years away. For a summary, see here; for the paper in the Astronomical Journal, see here.

Is the Sun’s 11-year Activity Peak Coming Early? The Sun’s 11-year cycle of activity is well-known, with the next maximum expected in mid-2025. But there are some indications that the peak may come earlier than usual this time around. Since solar activity can play hob with satellites, power transmission systems, and other technological infrastructure, having a good handle on its timing and severity ahead of time is crucial. For more on this issue, see: https://phys.org/news/2023-10-sun-peak-earlyknowing-secrets-star.html.

Without Infrastructure, Little is Possible: A truism in many contexts, including astronomy. For example, images from the James Webb Space Telescope dazzle professional astronomers and the public alike. The really-complex-yet-extremely-successful satellite is a marvel of engineering design and construction (as only NASA can!). But JWST would be of no value without the supporting infrastructure here on Earth that receives the information from its instruments.

Downlinks of data are always of paramount importance, but communicating with satellites in LEO or Geosynchronous orbit is simple compared with receiving data from JWST, which orbits the Sun-Earth L2 point, a million miles away. NASA’s Deep Space Network, originally built 60 years ago to ensure continuous radio contact with early manned spacecraft, is still up to the task! Although I’d bet that the electronics of their receivers and transmitters may have had an upgrade or two over the decades!

The DSN is an engineering marvel. For a summary, see here; for the DSN website, see here; and if you want to see whose signal the DSN is receiving, see here.

TWSftUoTtCBDftSoTiFoOT

The World Society for the Understanding of Things that Can Be Understood from the Study of Things in Front of Other Things says: An astonishing amount of Science can be conducted via the Study of Things in Front of Other Things! Examples range from the confirmation of Relativity by observations made during a total solar eclipse to asteroid shapes to rings around Uranus to planets of other Suns. Since many exoplanets have been discovered when they were “in front of other things,” all exoplanet and SETI news and info will be covered in the section below.

A Primer in Transits: NASA posted an introductory piece to the TWSFTUOTTCBDFTSOTIFOOT favorite of planetary transits here. Detecting the small drop in light from a star when its exoplanet transits across its face is one of the primary means of detecting exoplanets, enabled by ground-based observation and satellites like Kepler and TESS

Gliese 12 b, An Exo-Venus: Japanese astronomers have found an exoplanet only 40 light-years from Earth that is similar in size and stellar heating as Venus. Its sun, Gliese 12, is a red dwarf, and the newly-discovered exoplanet orbits it every 12.8 Earth days. Gliese 12 is about a quarter of the size of the Sun, and has a much cooler surface temperature, which would indicate that Gliese 12 b would have a surface temperature in the “Goldilocks Zone.” The discovery made the news last month, and the results, summarized here, were published in The Astrophysical Journal Letters (here) and the Monthly Notices of the Royal Astronomical Society.

SPECULOOsions About a Nearby Planet and Its Ultra-cool Star:  No, this is not yet another example of a Spell-Check error, rather it is about a news item from the Search for Planets EClipsing ULtra-cOOl stars Project. Jupiter needs just a bit more mass before its internal gravity is enough to initiate fusion. An Ultra-Cool star is one that has just a bit more mass than the absolute minimum to initiate fusion, making them the least-massive class of stars. One of them, located 55 light-years from Earth, has been found to have an Earth-sized exoplanet so close to its star that its year is only 17 hours long. The exoplanet gets about 16x the heating the Earth receives, in spite of its star’s dimness. This is only the second planetary system found to date around an ultra-cool star, but such stars “represent a significant fraction of the planetary population in the Milky Way,” so learning more about them is important. For a summary of this discovery, see: https://www.sciencedaily.com/releases/2024/05/240515122831.htm.

Search for Brown Dwarfs, Our “Cool Neighbors”: Ultra-cool stars (above) are the least-massive stars, just barely large enough to initiate hydrogen fusion in their cores. Brown dwarfs are bodies that were almost, but not quite, large enough to initiate fusion. The give off some radiation, mostly in the IR, due to internal heat left over from their formation, but so little that it makes them hard to find, even though they should be commonplace. Knowing more about them would inform models of star formation. Examination of the brown dwarfs discovered to date so them to contain water and methane, suggesting a kinship with exoplanets. Detailed examination of as many brown dwarfs as possible could give more insight into the formation of exoplanets and the spectrum of astronomical objects from stars to independent planets (those that don’t orbit stars). 

YOU can help astronomers search for brown dwarfs from the comfort of your own home. Find out more about it in the Citizen Science section below!

Volcanic Exoplanet: HD 104067 is a star system 66 light-years from Earth. The first-known planet in the system is a “super-Earth,” and recent analysis of TESS and other data have revealed two additional exoplanets there. The geometry of the Super-Earth’s orbit is distorted by the gravity of the other two, and the ellipticity so induced causes the Super-Earth to flex, generating considerable heat (the same is true for Jupiter’s moon, Io). Calculations suggest that the heating would cause widespread volcanic activity and a surface temperature above 2000 K. For more on this Klingon pleasure planet, see: https://www.sciencedaily.com/releases/2024/05/240509155528.htm.

Hell-Planet Atmosphere: 55 Cancri is a small star 41 light-years from Earth. One of its planets, 55 Cancri e, orbits only 1.4 million miles from its star, making its surface temperature extremely hot. It’s classed as a “Super Earth,” and there is a debate over whether or not it has an atmosphere, and if so, its composition. Some data from the Spitzer Space Telescope indicated a lot of volatiles in its atmosphere, but at the high temperature likely there the only gas would be vaporized rocks. However, recent results from the JWST indicate the surface temperature of 55 Cancri e is hot, but not as hot a previously thought, and it appears that some heat is taken to the night side of the exoplanet, suggesting a volatile-rich atmosphere. Also likely is that the exoplanet is covered by a “bubbling magma ocean.” For more info, see here, and DO NOT fall for the scam that it’s a nice place for a vacation home!

Could Evidence of Life Elsewhere Be Detected by the Europa Clipper? We know that several of the bodies in the outer Solar system have extensive, even global, liquid oceans under their icy crust. The surfaces of two, Jupiter’s Europa and Saturn’s Enceladus, have surfaces that in part resemble fractured pack ice on Earth. Some of Enceladus’ surface cracks are spewing a geyser of liquid, mostly water, from below, the droplets of water quickly freeing. The Cassini spacecraft, near the end of its operational life, was directed to fly through on such plume. Its instruments showed the water had a chemistry similar to that on Earth around a deep-water hot spring; all known such springs on Earth harbor a number of environment-specific life forms.

A recent study of how effective the Europa Clipper’s imaging system would be if it targeted a geyser plume in detecting biological chemistry in its component ice crystals. Experiments show a bio signature could be detected if even only 0.1% of the crystals imaged contained the bio material. For a summary of this interesting possibility, see: https://www.sciencedaily.com/releases/2024/03/240322145406.htm, and for the paper itself in Science Advances, see: https://www.science.org/doi/10.1126/sciadv.adl0849.

SEARCH FOR HABITABLE EXOPLANETS

Habitable Worlds Observatory: Yes, Virginia, there will be such a thing in the future. The 2020 Astronomy Decadal Survey strongly recommended that NASA “develop a 6-meter Space telescope capable of high-contrast observations in optical, infra-red, and ultraviolet wavelengths.” Its primary mission will be to examine 25 different exoplanets in detail, all in their star’s “Goldilocks Zone,” searching for biosignatures. Knowing which stars to choose is obviously of great importance. That work is presently underway; NASA’s Exoplanet Exploration Program has developed a list of 164 candidates to date, based on five selection criteria: stellar composition, photometric values, flare rate, variability, and potentially-sterilizing X-ray emissions. For more information on this project, see: https://phys.org/news/2024-01-astronomers-habitable-worlds-observatory.html and https://science.nasa.gov/astrophysics/programs/habitable-worlds-observatory.

SEARCH FOR INTELLIGENT LIFE ELSEWHERE

Part 1: UCLA’s Jean-Luc Margot is the founder of UCLA SETI’s “Are We Alone in the Universe?” project. Their mission is to detect “technosignatures by searching individual systems. Dr. Margot teaches a graduate course in SETI, and he had his students use TESS data for the closer known exoplanets to narrow the search for such emissions in great detail. No provable technosignatures were seen. Even though the smally sample observed didn’t show emissions, the skills developed by the students (e.g. signal processing, telecommunications, and statistics and other data analysis tools) will no doubt improve their academic success.

Part 2: Traditional SETI tactics, like Dr. Margot’s project, is one way to search. The Breakthrough Listen program (which uses citizen scientists) takes a different approach. Rather than look at relatively-close systems, they are using the Green Bank (West Virginia) and Parkes Murriyang radio telescopes to look for very high powered technosignatures, an entire galaxy at a time. For more on this program and strategy, see: https://phys.org/news/2023-12-breakthrough-scans-entire-galaxies-extremely.html.

Part 3: NASA has produced a six-part on-line series on how it is searching for life in the cosmos. If you are interested in the real science behind this topic, then check out these episodes! Part 1: Beginnings: Life on Our World and Others; Part 2: Life on Other Planets: What is Life and What Does It Need?; Part 3: The Hunt for Life on Mars – and Elsewhere in the Solar System; Part 4: “Life” in the Lab; Part 5: Searching for Signs of Intelligent Life: Technosignatures (see also this week’s Gravity Assist entry in the Solar System section); and Part 6: Finding Life Beyond Earth: What Comes Next?

What Happens After We Discover Life Elsewhere? Mary Voytek, Director of NASA’s Astrobiology Program, has some interesting thoughts on the subject. Check them out at: https://exoplanets.nasa.gov/news/1766/finding-life-beyond-earth-what-comes-next!

Exoplanet Travel Bureau is NASA’s source for whimsical travel posters showcasing various exoplanets as tourist destinations and other exoplanet information. See: https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau!

The Nature of Dark Matter: Dark matter doesn’t emit, absorb, or reflect light, which makes it had to investigate. However, dark matter does have gravity, and therefore, can deflect light. Gravitational lensing by conventional matter has been amply documented, and has been used scientifically for more than a century (deflection observed by the Sun during the 1919 total solar eclipse helped confirm Einstein’s predictions; see here). 

When the bright light, such as a quasar, is almost exactly behind a massive foreground object as seen from Earth, the light follows multiple paths around the object, causing us to see multiple images of the same distant light. Such a cluster of images is called an “Einstein Cross,” and a number of examples have been known for some time. The JWST will reveal many more, and a detailed study of them may reveal the nature of dark matter. For more on this research, see the cosmology article in the September, 2023, issue of Sky & Telescope magazine, p. 8-9, or the phys.org note here: https://phys.org/news/2023-04-einstein-distant-galaxies-closer-dark.html.

Gravitational Lenses and SETI: Research has been underway for some time to assess the possibility of using the Sun as a gravitational lens to allow the study of exoplanets in detail not otherwise available and to even assist the search for extraterrestrial intelligence. Some are now hypothesizing that using the Sun as a lens could facilitate the construction of an interstellar communications network, which has implications on our search for technosignatures (see also immediately below). Even more interestingly, the prospect that other civilizations could use lenses as a way to send power from one stellar system to another. For more on this intriguing idea, see here: https://phys.org/news/2023-11-civilizations-gravitational-lenses-transmit-power.html.

Drake Award: The SETI Institute has awarded the 2023 Drake Award, which recognizes outstanding achievements in furthering understanding of the potential for life elsewhere in the Universe, to NASA’s John Rummel. He was cited for “extraordinary and innovative programmatic contributions and unwavering advocacy for SETI and astrobiology.” For more, see here and here.

Underground Oceans and Life: Worlds with subsurface bodies of water are found throughout the outer Solar System. At least some of them have volcanic activity at their bottoms. What are the implications for life in such environments? If such habitats develop, they will be difficult to detect from afar; how does that affect the search for extra-terrestrial civilizations? For more on this topic, see here.

Two Water Worlds, Too (Maybe): An astronomer team has found two exoplanets in a system 218 light-years away that appear likely to be composed largely of water. The Kepler-138 planetary system has two planets a bit larger than Earth, with three times the volume but only twice as much mass. No chemical analysis of their surfaces has been made to date, but estimates of their density, if true, require them to have a composition of something much less dense than rock; water being the most likely candidate. For more on this system, see: https://phys.org/news/2022-12-montreal-astronomers-exoplanets.html. Now please excuse me as I have a Robert Forward Rocheworld flashback …

Satellites vs. Astronomy: Learning about a Thing when another Thing Passes in Front of It is wonderful. However, not always.LEO is getting extremely crowded, so much so that astronomical observations, both amateur and professional, are starting to get adversely affected often. Images from Space-based platforms are increasingly affected, too. A case in point is the Hubble Space Telescope. In its early days, HST images rarely captured a satellite passing in front of the object of study, but the number of affected images has grown dramatically, largely due to the launch of entire constellations of satellites, such as that supporting Starlink and One Web. The citizen science program called Hubble Asteroid Hunter recruited over 11,000 citizen astronomers to analyze HST images, first for asteroids, then for satellite interference (see more about the HAH in the Citizen Science section of the website). The percentage of affected images is now over 5.9% (as of 2020) and growing rapidly. Several recent articles describe this problem, for example: Phys.org (here) and Sky & Telescope (here). Radio astronomy is also being adversely affected, see here.

The Sun as a Telescope: You’ve seen me mention that there is a mutual interaction between scientific inquiry and the technologies that enable it. We form hypotheses about the Universe around us, then we envision, design, and build technology to help us answer questions raised by those hypotheses. The answered questions lead to more questions, which leads to more technology, etc., a “Virtuous Circle.” Here’s a recent example.

Fact 1: Astronomers have now discovered over 5000 planets orbiting other stars, most via the transit method. Fact 2: Recall that Eddington observed how starlight was deflected slightly by Sun’s gravitational field in 1919, and astronomers routinely use gravitational “lensing” to detect the presence of astronomical “things in front of other things.”

Well, some clever astronomers have explored the opportunity of combining those two facts, and to use the Sun’s gravity to actually make crude images of the surfaces of exoplanets. This technique could increase imaging capabilities by three orders of magnitude. Sounds impossible, but check out the summary at: https://phys.org/news/2022-05-scientists-gravity-telescope-image-exoplanets.html and/or the paper in The Astrophysical Journal here: https://iopscience.iop.org/article/10.3847/1538-4357/ac5e9d! Now THAT’s a great TWSftUoTtCBDftSoTiFoOT story!

NOTE: The “double transit” observation is important! One of the arguments against TESS and exoplanet detection is that the dips in brightness observed by TESS could be caused by darker spots on the star, rather than an exoplanet transit. But if the dip is observed first for one star, then the other, of a binary system, it couldn’t very well be due to a “star-spot!”

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