Wednesday, January 15, 2025

 SPACE/COSMOS

NASA celebrates Edwin Hubble’s discovery of a new universe



NASA/Goddard Space Flight Center

Hubble M31 Cepheid Variable Star V1 

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In commemoration of Edwin Hubble's discovery of a Cepheid variable class star, called V1, in the neighboring Andromeda galaxy 100 years ago, astronomers partnered with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, producing a plot, or light curve, of the rhythmic rise and fall of the star's light. Based on this data, the Hubble Space Telescope was scheduled to capture the star at its dimmest and brightest light. Edwin Hubble's observations of V1 became the critical first step in uncovering a larger, grander universe than some astronomers imagined at the time. Once dismissed as a nearby "spiral nebula" measurements of Andromeda with its embedded Cepheid star served as a stellar milepost marker. It definitively showed that Andromeda was far outside of our Milky Way. Edwin Hubble went on to measure the distances to many galaxies beyond the Milky Way by finding Cepheid variables within those levels. The velocities of those galaxies, in turn, allowed him to determine that the universe is expanding.

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Credit: NASA, ESA, Hubble Heritage Project (STScI, AURA); Acknowledgment: Robert Gendler



For humans, the most important star in the universe is our Sun. The second-most important star is nestled inside the Andromeda galaxy. Don't go looking for it — the flickering star is 2.2 million light-years away, and is 1/100,000th the brightness of the faintest star visible to the human eye.

Yet, a century ago, its discovery by Edwin Hubble, then an astronomer at Carnegie Observatories, opened humanity's eyes as to how large the universe really is, and revealed that our Milky Way galaxy is just one of hundreds of billions of galaxies in the universe ushered in the coming-of-age for humans as a curious species that could scientifically ponder our own creation through the message of starlight. Carnegie Science and NASA are celebrating this centennial at the 245th meeting of the American Astronomical Society in Washington, D.C.

The seemingly inauspicious star, simply named V1, flung open a Pandora's box full of mysteries about time and space that are still challenging astronomers today. Using the largest telescope in the world at that time, the Carnegie-funded 100-inch Hooker Telescope at Mount Wilson Observatory in California, Hubble discovered the demure star in 1923. This rare type of pulsating star, called a Cepheid variable, is used as milepost markers for distant celestial objects. There are no tape-measures in space, but by the early 20th century Henrietta Swan Leavitt had discovered that the pulsation period of Cepheid variables is directly tied to their luminosity.

Many astronomers long believed that the edge of the Milky Way marked the edge of the entire universe. But Hubble determined that V1, located inside the Andromeda "nebula," was at a distance that far exceeded anything in our own Milky Way galaxy. This led Hubble to the jaw-dropping realization that the universe extends far beyond our own galaxy.

In fact Hubble had suspected there was a larger universe out there, but here was the proof in the pudding. He was so amazed he scribbled an exclamation mark on the photographic plate of Andromeda that pinpointed the variable star.

As a result, the science of cosmology exploded almost overnight. Hubble's contemporary, the distinguished Harvard astronomer Harlow Shapley, upon Hubble notifying him of the discovery, was devastated. "Here is the letter that destroyed my universe," he lamented to fellow astronomer Cecilia Payne-Gaposchkin, who was in his office when he opened Hubble's message.

Just three years earlier, Shapley had presented his observational interpretation of a much smaller universe in a debate one evening at the Smithsonian Museum of Natural History in Washington. He maintained that the Milky Way galaxy was so huge, it must encompass the entirety of the universe. Shapley insisted that the mysteriously fuzzy "spiral nebulae," such as Andromeda, were simply stars forming on the periphery of our Milky Way, and inconsequential.

Little could Hubble have imagined that 70 years later, an extraordinary telescope named after him, lofted hundreds of miles above the Earth, would continue his legacy. The marvelous telescope made "Hubble" a household word, synonymous with wonderous astronomy.

Today, NASA's Hubble Space Telescope pushes the frontiers of knowledge over 10 times farther than Edwin Hubble could ever see. The space telescope has lifted the curtain on a compulsive universe full of active stars, colliding galaxies, and runaway black holes, among the celestial fireworks of the interplay between matter and energy.

Edwin Hubble was the first astronomer to take the initial steps that would ultimately lead to the Hubble Space Telescope, revealing a seemingly infinite ocean of galaxies. He thought that, despite their abundance, galaxies came in just a few specific shapes: pinwheel spirals, football-shaped ellipticals, and oddball irregular galaxies. He thought these might be clues to galaxy evolution – but the answer had to wait for the Hubble Space Telescope's legendary Hubble Deep Field in 1994.

The most impactful finding that Edwin Hubble's analysis showed was that the farther the galaxy is, the faster it appears to be receding from Earth. The universe looked like it was expanding like a balloon. This was based on Hubble tying galaxy distances to the reddening of light — the redshift – that proportionally increased the father away the galaxies are.

The redshift data were first collected by Lowell Observatory astronomer Vesto Slipher, who spectroscopically studied the "spiral nebulae" a decade before Hubble. Slipher did not know they were extragalactic, but Hubble made the connection. Slipher first interpreted his redshift data an example of the Doppler effect. This phenomenon is caused by light being stretched to longer, redder wavelengths if a source is moving away from us. To Slipher, it was curious that all the spiral nebulae appeared to be moving away from Earth.

Two years prior to Hubble publishing his findings, the Belgian physicist and Jesuit priest Georges Lemaître analyzed the Hubble and Slifer observations and first came to the conclusion of an expanding universe. This proportionality between galaxies' distances and redshifts is today termed Hubble–Lemaître's law.

Because the universe appeared to be uniformly expanding, Lemaître further realized that the expansion rate could be run back into time – like rewinding a movie – until the universe was unimaginably small, hot, and dense. It wasn't until 1949 that the term "big bang" came into fashion.

This was a relief to Edwin Hubble's contemporary, Albert Einstein, who deduced the universe could not remain stationary without imploding under gravity's pull. The rate of cosmic expansion is now known as the Hubble Constant.

Ironically, Hubble himself never fully accepted the runaway universe as an interpretation of the redshift data. He suspected that some unknown physics phenomenon was giving the illusion that the galaxies were flying away from each other. He was partly right in that Einstein's theory of special relativity explained redshift as an effect of time-dilation that is proportional to the stretching of expanding space. The galaxies only appear to be zooming through the universe. Space is expanding instead.

After decades of precise measurements, the Hubble telescope came along to nail down the expansion rate precisely, giving the universe an age of 13.8 billion years. This required establishing the first rung of what astronomers call the "cosmic distance ladder" needed to build a yardstick to far-flung galaxies. They are cousins to V1, Cepheid variable stars that the Hubble telescope can detect out to over 100 times farther from Earth than the star Edwin Hubble first found.

Astrophysics was turned on its head again in 1998 when the Hubble telescope and other observatories discovered that the universe was expanding at an ever-faster rate, through a phenomenon dubbed "dark energy." Einstein first toyed with this idea of a repulsive form of gravity in space, calling it the cosmological constant.

Even more mysteriously, the current expansion rate appears to be different than what modern cosmological models of the developing universe would predict, further confounding theoreticians. Today astronomers are wrestling with the idea that whatever is accelerating the universe may be changing over time. NASA's Roman Space Telescope, with the ability to do large cosmic surveys, should lead to new insights into the behavior of dark matter and dark energy. Roman will likely measure the Hubble constant via lensed supernovae.

This grand century-long adventure, plumbing depths of the unknown, began with Hubble photographing a large smudge of light, the Andromeda galaxy, at the Mount Wilson Observatory high above Los Angeles.

In short, Edwin Hubble is the man who wiped away the ancient universe and discovered a new universe that would shrink humanity's self-perception into being an insignificant speck in the cosmos.

The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.


Compass and scale image titled "Cepheid Variable Star V1 in M31 HST WFC3/UVIS." Four boxes each showing a bright white star in the center surrounded by other stars. Each box has a correlating date at the bottom: Dec. 17, 2020, Dec. 21, 2010, Dec. 30, 2019, and Jan. 26, 2011. The center star in the boxes appears brighter with each passing date.

Credit

NASA, ESA, Hubble Heritage Project (STScI, AURA)

Explore More

Edwin Hubble

Hubble Views the Star That Changed the Universe

The History of Hubble

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This quasar may have helped turn the lights on for the universe



Yale University




New Haven, Conn. — A Yale-led team of astronomers has detected an intensely brightening and dimming quasar that may help explain how some objects in the early universe grew at a highly accelerated rate.

The discovery, announced Jan. 14 at the winter meeting of the American Astronomical Society, is the most distant object detected by the NuSTAR X-ray space telescope (which launched in 2012) and stands as one of the most highly “variable” quasars ever identified.

“In this work, we have discovered that this quasar is very likely to be a supermassive black hole with a jet pointed towards Earth — and we are seeing it in the first billion years of the universe,” said Lea Marcotulli, a postdoctoral fellow in astrophysics at Yale and lead author of a new study published Jan. 14 in The Astrophysical Journal Letters.

Quasars are among the oldest, brightest objects in the universe. Formed from active galactic nuclei (AGN) — areas at the center of galaxies where a black hole is drawing in matter — quasars emit electromagnetic radiation that can be spotted in radio, infrared, visible, ultraviolet, X-ray, and gamma-ray wavelengths. This “visibility” has made quasars a helpful proxy for trying to understand the structure and evolution of the cosmos.

For example, astronomers look to quasars to study reionization, a period less than a billion years after the Big Bang when electrically neutral hydrogen atoms became charged and the first generation of stars lit up the universe.

“The epoch of reionization is considered the end of the universe’s dark ages,” said Thomas Connor, an astronomer at the Chandra X-Ray Center and co-corresponding author of the study. “The precise timeline and source class responsible for reionization are still debated, and actively accreting supermassive black holes are one proposed culprit.”

For the study, the researchers compared NuSTAR observations of a distant quasar — designated J1429+5447 — with unrelated observations of four months earlier by the Chandra X-ray telescope. The researchers found that the quasar’s X-ray emissions had doubled in that very short time (due to relativistic effects, the four months on Earth corresponded to only two weeks for the quasar).

“This level of X-ray variability, in terms of intensity and rapidity, is extreme,” said Meg Urry, the Israel Munson Professor of Physics and Astronomy in Yale’s Faculty of Arts and Sciences and co-author of the study. “It is almost certainly explained by a jet pointing toward us — a cone in which particles are transported up to a million light years away from the central, supermassive black hole. Because the jet moves at nearly the speed of light, effects of Einstein’s theory of special relativity speed up and amplify the variability.”

The researchers said their findings offer crucial, much-needed information for astronomers studying reionization. It may also point astronomers toward other supermassive black hole candidates from the early universe.

“Finding more supermassive black holes that are potentially hosting jets raises the question as to how these black holes grew so big in such a short timescale, and what the connection may be to jet triggering mechanisms,” Marcotulli said.

NASA supported the research.

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US, Japanese lunar landers set to launch on single rocket


By AFP
January 14, 2025


This undated handout image courtesy of Firefly Aerospace shows the fully assembled Blue Ghost Mission 1 lunar lander vehicle - Copyright Firefly Aerospace/AFP/File -


Issam AHMED

One rocket, two missions: Lunar landers built by US and Japanese companies are poised to “rideshare” to the Moon, showcasing the private sector’s growing role in space exploration.

SpaceX is targeting a 1:11 am (0611 GMT) Wednesday liftoff of a Falcon 9 rocket from the Kennedy Space Center in Florida, with very favorable weather conditions forecast.

On board are two privately developed, uncrewed lunar landers: Firefly Aerospace’s Blue Ghost and ispace’s Resilience from Japan, which will also deploy a micro rover.

Both aim to build on the success of Texas-based Intuitive Machines, which last year became the first company to successfully touch down on Earth’s celestial neighbor.

Until recently, soft landings on the Moon were achieved only by a handful of well-funded national space agencies, starting with the Soviet Union in 1966.

Now, however, several emerging US companies are attempting to replicate this feat under NASA’s experimental Commercial Lunar Payload Services (CLPS) program, designed to cut costs and stimulate a lunar economy.

The US plans to establish a sustained human presence on the Moon later this decade under the Artemis program, leveraging commercial partners to deliver critical hardware at a fraction of the cost of government-led missions.

“Each milestone we complete will provide valuable data for future missions and ultimately keep the United States and our international partners at the forefront of space exploration,” Firefly Aerospace CEO Jason Kim said Tuesday.

“Firefly is a go for launch. Let’s go ghost riders in the sky!”



– Staying upright –



On the Japanese side, Tokyo-based ispace’s first attempt to land on the Moon ended in an unsalvageable “hard landing” in April 2023.

“That’s why we hope to send a message to people across Japan that it’s important to challenge ourselves again, after enduring failure and learning from it,” ispace founder and CEO Takeshi Hakamada said last week.

Blue Ghost is stacked atop Resilience inside the Falcon 9, SpaceX executive Julianna Scheiman said, and will be deployed first, followed by Resilience nearly 30 minutes later.

The two spacecraft have different timelines for reaching the Moon.

Blue Ghost aims to complete its journey in 45 days, gradually lifting its orbit around Earth before entering lunar orbit and touching down near Mons Latreille, a volcanic feature in Mare Crisium on the Moon’s northeast near side.

“With ten NASA instruments on this flight, we’re conducting scientific investigations… from characterizing Earth’s magnetosphere to understanding lunar dust and the Moon’s interior structure and thermal properties,” NASA scientist Maria Banks said.

Blue Ghost also carries technology demonstrations focused on navigation and computing in the Moon’s harsh radiation environment.

Meanwhile, Resilience will take four to five months to reach its destination in Mare Frigoris, on the Moon’s far north.

Its payload includes scientific instruments, but the centerpiece is Tenacious, a micro rover developed by ispace-Europe, a Luxembourg-based subsidiary.

The four-wheeled robot features a high-definition camera and will attempt to scoop up regolith — the Moon’s loose surface material.

It also carries on its front a small red “Moonhouse” created by Swedish artist Mikael Genberg.

These ambitious goals hinge on achieving a successful soft landing — a task fraught with challenges.

Spacecraft must navigate treacherous boulders and craters and, in the absence of an atmosphere to support parachutes, rely entirely on thrusters for a controlled descent.

A final hurdle, as recent missions have shown, is remaining upright.

When Intuitive Machines’ Odysseus landed in April 2024, it tipped over, limiting the investigations it could perform.

Similarly, Japan’s SLIM lander, which touched down in March 2024, landed at a wonky angle, leaving its solar panels poorly positioned, similarly curtailing its operational lifespan.


Not all Hot Jupiters orbit solo



A UNIGE study shows that Hot Jupiters do not systematically eject their planetary neighbours during migration. This discovery overturns our perception of the architecture of planetary systems



Université de Genève

Not all Hot Jupiters orbit solo 

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The WASP-132 system contains a Hot Jupiter (in the foreground), an inner super-Earth (here transiting in front of the orange host star) and the planet WASP-132d, discovered towards the outside of the system.

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Credit: © Thibaut Roger - Université de Genève




Hot Jupiters are giant planets initially known to orbit alone close to their star. During their migration towards their star, these planets were thought to accrete or eject any other planets present. However, this paradigm has been overturned by recent observations, and the final blow could come from a new study led by the University of Geneva (UNIGE). A team including the National Centre of Competence in Research (NCCR) PlanetS, the Universities of Bern (UNIBE) and Zurich (UZH) and several foreign universities has just announced the existence of a planetary system, WASP-132, with an unexpected architecture. It not only contains a Hot Jupiter but also an inner Super-Earth and an icy giant planet. These results are published in Astronomy & Astrophysics.


Hot Jupiters are planets with masses similar to that of Jupiter, but orbit close to their star, at a much smaller distance than Mercury is to the Sun. It is difficult for these giant planets to form where they are observed, because there is not enough gas and dust close to the star. They must therefore form far from it and migrate as the planetary system evolves.


Until recently, astronomers observed that Hot Jupiters were isolated around their star, with no other planets in their vicinity. This observation seemed all the more solid as there was a theory to explain it. The processes involved in the migration of giant planets towards their star lead to the accretion or ejection of any planets in an inner orbit. But recent observations suggest other scenarios.


A team led by the Astronomy Department of the UNIGE Faculty of Science, in partnership with UNIBE and UZH, as part of the NCCR PlanetS, and with other international institutions such as the University of Warwick, has just confirmed this trend. The scientists have discovered the existence of a multi-planetary system made up of a Hot Jupiter, an inner Super-Earth (even closer to the star than the hot Jupiter) and an outer massive giant planet (much further away from the star than the Hot Jupiter). If Hot Jupiters are not always alone in their planetary system, then their migration process must be different in order to preserve the architecture of the system.


A unique multi-planetary system

The WASP-132 system is a unique multi-planetary system. It contains a Hot Jupiter that orbits its star in 7 days and 3 hours; a Super-Earth (a rocky planet 6 times the mass of the Earth) that orbits the star in just 24 hours and 17 minutes; and a giant planet (5 times the mass of Jupiter) that orbits the host star in 5 years. In addition, a much more massive companion, probably a brown dwarf (a celestial body whose mass is between that of a planet and that of a star), orbits at a very long distance.


‘‘The WASP-132 system is a remarkable laboratory for studying the formation and evolution of multi-planetary systems. The discovery of a Hot Jupiter alongside an inner Super-Earth and a distant giant planet calls into question our understanding of the formation and evolution of these systems,’’ says François Bouchy, associate professor in the Department of Astronomy at the UNIGE Faculty of Science and co-author of the study. ‘‘This is the first time we have observed such a configuration!,’’ adds Solène Ulmer-Moll, a postdoctoral researcher at UNIGE and UNIBE at the time of the study and co-author of the paper.


Eighteen years of observation

For exoplanetologists, the story of the star WASP-132 began in 2006, as part of the Wide-Angle Search for Planets (WASP) program. In 2012, the accumulation of more than 23,000 photometric measurements made it possible to identify a planetary candidate, WASP-132b, with a radius of 0.87 times Jupiter’s and an orbital period of 7.1 days. In 2014, the CORALIE spectrograph, installed on the Swiss Euler telescope and led by the UNIGE, began a campaign to monitor this candidate. In 2016, WASP-132b was confirmed and its mass was measured to be equal to 0.41 Jupiter masses. Furthermore the CORALIE measurements indicate the presence of another giant planet with a very long period.


Around the same star, at the end of 2021, the TESS space telescope revealed the signal from a transiting Super-Earth with a diameter of 1.8 Earth radii and a period of only 1.01 days. In the first half of 2022, the HARPS spectrograph at the La Silla observatory measured the mass of this Super-Earth, which is six times the mass of Earth, as part of a program led by David Armstrong from the University of Warwick.


‘‘The detection of the inner Super-Earth was particularly exciting,’’ explains Nolan Grieves, a postdoctoral researcher in the Department of Astronomy at the UNIGE Faculty of Science at the time of the study, and first author of the paper. ‘‘We had to carry out an intensive campaign using HARPS and optimised signal processing to characterise its mass, density and composition, revealing a planet with a density similar to that of the Earth’’.


Observations of WASP-132 are not over yet, however, as ESA’s Gaia satellite has been measuring the minute variations in the positions of stars since 2014, with an aim to reveal their planetary companions and outer brown dwarfs.


A new understanding of planet formation

The discovery of an outer cold giant planet and an inner Super-Earth adds another layer of complexity to the WASP-132 system. The standard hypothesis of migration by dynamical perturbation of the Hot Jupiter towards the interior does not hold, as this would have destabilised the orbits of the other two planets. Instead, their presence suggests a more stable and dynamically ‘‘cool’’ migration path in a proto-planetary disc for the hot Jupiter, preserving its neighbours.


The combination of precise radius and mass measurements has also made it possible to determine the density and internal composition of the planets. The Hot Jupiter WASP-132b reveals a heavy element enrichment of around 17 Earth masses, in agreement with models of gas giant formation. The Super-Earth has a composition dominated by metals and silicates that is fairly similar to that of the Earth.


‘‘The combination of a Hot Jupiter, an inner Super-Earth and an outer giant planet in the same system provides important constraints on theories of planet formation and in particular their migration processes,’’ concludes Ravit Helled, professor at the UZH and co-author of the study. ‘‘WASP-132 demonstrates the diversity and complexity of multi-planetary systems, underlining the need for very long-term, high-precision observations.’’

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