SPACE/COSMOS
NASA celebrates Edwin Hubble’s discovery of a new universe
NASA/Goddard Space Flight Center
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
Hubble Views the Star That Changed the Universe
Follow Hubble on: Facebook @NASAHubble, X @NASAHubble, and Instagram @NASAHubble
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.
# # #
Journal
The Astrophysical Journal
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
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.’’
Journal
Astronomy and Astrophysics
Method of Research
News article
Subject of Research
Not applicable
Article Title
''Discovery of a cold giant planet and mass measurement of a hot super-Earth in the multi-planetary system WASP-132''
Article Publication Date
15-Jan-2025
Discovery of two planets sheds new light on the formation of planetary systems
University of Warwick
The discovery of two new planets beyond our solar system by a team of astronomers from The University of Warwick and the University of Geneva (UNIGE), is challenging scientific understanding of how planetary systems form.
The existence of these two exoplanets - an inner super-Earth and an outer icy giant planet - within the WASP-132 system is overturning accepted paradigms of how ‘hot Jupiter’ planetary systems form and evolve.
Hot Jupiters are planets with masses similar to those of Jupiter, but which orbit closer to their star than Mercury orbits the Sun. There is not enough gas and dust for these giant planets to form where they are observed, so the accepted theory is that they originate far from their star and migrate inward as the planetary system evolves.
Until now, hot Jupiters were thought to orbit their star alone, as migration towards the star would eject other planets in the system. The research team’s recent observations of two extra planets in the WASP-132 system now calls into question this theory.
David Armstrong, Associate Professor of Physics, The University of Warwick said, “The detection of the inner super-Earth was exciting as it’s particularly rare to find planets interior to hot Jupiters. We carried out an intensive campaign with state-of-the-art instruments to characterise its mass, density and composition, revealing a planet with a density similar to that of the Earth”.
This planetary discovery adds a layer of complexity to the WASP-132 system as migration of a hot Jupiter towards its star through dynamical perturbation would destabilise the orbits of the other two planets. This suggests a more stable ‘cool’ migration path for the hot Jupiter in a proto-planetary disc that surrounds a young star and is the site of planet formation.
“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 calls into question our understanding of the formation and evolution of these systems. This is the first time we have observed such a configuration”, says François Bouchy, Associate Professor, Department of Astronomy, UNIGE Faculty of Science.
The hot Jupiter orbits its star in seven days and three hours; the super-Earth (a rocky planet six times the mass of the Earth) orbits the star in just 24 hours and 17 minutes; and the icy giant (five times the mass of Jupiter) orbits the host star in five years. The precise measurements of radius and mass have also made it possible to determine the density and internal composition of the planets. The super-Earth composition is dominated by metals and silicates, similar to that of Earth.
Observations of WASP-132 continue, with the ESA's Gaia satellite measuring minute variations in the positions of stars since 2014, with a view to revealing their planetary companions and outer brown dwarfs.
The full paper is a collaboration between Warwick and the University of Geneva and can be read in Astronomy & Astrophysics: 2025, A&A, 693, A144
DOI: 10.1051/0004-6361/202348177
Notes to the editor
In 2006, research began on exoplanets as part of the Wide Angle Search for Planets (WASP) programme.
University of Warwick
The University of Warwick is one of the UK’s leading universities, marking its 60th anniversary in 2025. With over twenty-eight thousand students from 147 countries, it's currently ranked 9th in the UK by The Guardian University Guide. It has an acknowledged reputation for excellence in research and teaching, for innovation, and for links with business and industry. The recent Research Excellence Framework classed 92% of its research as ‘world leading’ or ‘internationally excellent’. The University of Warwick was awarded Midlands University of the Year by The Times and Sunday Times.
In this artist’s concept, matter is stripped from a white dwarf (sphere at lower right) orbiting within the innermost accretion disk surrounding 1ES 1927+654’s supermassive black hole. Astronomers developed this scenario to explain the evolution of rapid X-ray oscillations detected by ESA’s (European Space Agency) XMM-Newton satellite. ESA’s LISA (Laser Interferometer Space Antenna) mission, due to launch in the next decade, should be able to confirm the presence of an orbiting white dwarf by detecting the gravitational waves it produces.
Credit
NASA/Aurore Simonnet, Sonoma State University
Usage Restrictions
Journal
Astronomy and Astrophysics
Subject of Research
Not applicable
Article Publication Date
15-Jan-2025
Astronomers catch unprecedented features at brink of active black hole
NASA/Goddard Space Flight Center
International teams of astronomers monitoring a supermassive black hole in the heart of a distant galaxy have detected features never seen before using data from NASA missions and other facilities. The features include the launch of a plasma jet moving at nearly one-third the speed of light and unusual, rapid X-ray fluctuations likely arising from near the very edge of the black hole.
The source is 1ES 1927+654, a galaxy located about 270 million light-years away in the constellation Draco. It harbors a central black hole with a mass equivalent to about 1.4 million Suns.
“In 2018, the black hole began changing its properties right before our eyes, with a major optical, ultraviolet, and X-ray outburst,” said Eileen Meyer, an associate professor at UMBC (University of Maryland Baltimore County). “Many teams have been keeping a close eye on it ever since.”
She presented her team’s findings at the 245th meeting of the American Astronomical Society in National Harbor, Maryland. A paper led by Meyer describing the radio results was published Jan. 13 in The Astrophysical Journal Letters.
After the outburst, the black hole appeared to return to a quiet state, with a lull in activity for nearly a year. But by April 2023, a team led by Sibasish Laha at UMBC and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, had noted a steady, months-long increase in low-energy X-rays in measurements by NASA’s Neil Gehrels Swift Observatory and NICER (Neutron star Interior Composition Explorer) telescope on the International Space Station. This monitoring program, which also includes observations from NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) and ESA’s (European Space Agency) XMM-Newton mission, continues.
The increase in X-rays triggered the UMBC team to make new radio observations, which indicated a strong and highly unusual radio flare was underway. The scientists then began intensive observations using the NRAO’s (National Radio Astronomy Observatory) VLBA (Very Long Baseline Array) and other facilities. The VLBA, a network of radio telescopes spread across the U.S., combines signals from individual dishes to create what amounts to a powerful, high-resolution radio camera. This allows the VLBA to detect features less than a light-year across at 1ES 1927+654’s distance.
Radio data from February, April, and May 2024 reveals what appear to be jets of ionized gas, or plasma, extending from either side of the black hole, with a total size of about half a light-year. Astronomers have long puzzled over why only a fraction of monster black holes produce powerful plasma jets, and these observations may provide critical clues.
“The launch of a black hole jet has never been observed before in real time,” Meyer noted. “We think the outflow began earlier, when the X-rays increased prior to the radio flare, and the jet was screened from our view by hot gas until it broke out early last year.”
A paper exploring that possibility, led by Laha, is under review at The Astrophysical Journal. Both Meyer and Megan Masterson, a doctoral candidate at the Massachusetts Institute of Technology in Cambridge who also presented at the meeting, are co-authors.
Using XMM-Newton observations, Masterson found that the black hole exhibited extremely rapid X-ray variations between July 2022 and March 2024. During this period, the X-ray brightness repeatedly rose and fell by 10% every few minutes. Such changes, called millihertz quasiperiodic oscillations, are difficult to detect around supermassive black holes and have been observed in only a handful of systems to date.
“One way to produce these oscillations is with an object orbiting within the black hole’s accretion disk. In this scenario, each rise and fall of the X-rays represents one orbital cycle,” Masterson said.
If the fluctuations were caused by an orbiting mass, then the period would shorten as the object fell ever closer to the black hole’s event horizon, the point of no return. Orbiting masses generate ripples in space-time called gravitational waves. These waves drain away orbital energy, bringing the object closer to the black hole, increasing its speed, and shortening its orbital period.
Over two years, the fluctuation period dropped from 18 minutes to just 7 — the first-ever measurement of its kind around a supermassive black hole. If this represented an orbiting object, it was now moving at half the speed of light. Then something unexpected happened — the fluctuation period stabilized.
“We were shocked by this at first,” Masterson explained. “But we realized that as the object moved closer to the black hole, its strong gravitational pull could begin to strip matter from the companion. This mass loss could offset the energy removed by gravitational waves, halting the companion’s inward motion.”
So what could this companion be? A small black hole would plunge straight in, and a normal star would quickly be torn apart by the tidal forces near the monster black hole. But the team found that a low-mass white dwarf — a stellar remnant about as large as Earth — could remain intact close to the black hole’s event horizon while shedding some of its matter. A paper led by Masterson summarizing these results will appear in the Feb. 13 edition of the journal Nature.
This model makes a key prediction, Masterson notes. If the black hole does have a white dwarf companion, the gravitational waves it produces will be detectable by LISA (Laser Interferometer Space Antenna), an ESA mission in partnership with NASA that is expected to launch in the next decade.
Journal
The Astrophysical Journal Letters
Article Title
Late-time Radio Brightening and Emergence of a Radio Jet in the Changing-look AGN 1ES 1927+654
Article Publication Date
14-Jan-2025
DECam and Gemini South discover three tiny ‘stellar-ghost-town’ galaxies
Rare ultra-faint dwarf galaxies beyond the influence of other galaxies show evidence that star formation was stifled long ago
Ultra-faint dwarf galaxies are the faintest type of galaxy in the Universe. Typically containing just a few hundred to a thousand stars — compared with the hundreds of billions that make up the Milky Way — these small diffuse structures usually hide inconspicuously among the many brighter residents of the sky. For this reason, astronomers have previously had the most luck finding them nearby, in the vicinity of our own Milky Way Galaxy.
But this presents a problem for understanding them; the Milky Way’s gravitational forces and hot corona can strip away the dwarf galaxies’ gas and interfere with their natural evolution. Additionally, further out beyond the Milky Way, ultra-faint dwarf galaxies increasingly become too diffuse and unresolvable for astronomers and traditional computer algorithms to detect.
That’s why a manual, by-eye search by University of Arizona astronomer David Sand was needed to discover three faint and ultra-faint dwarf galaxies located in the direction of spiral galaxy NGC 300 and the Sculptor constellation. “It was during the pandemic,” recalls Sand. “I was watching TV and scrolling through the DESI Legacy Survey viewer, focusing on areas of sky that I knew hadn't been searched before. It took a few hours of casual searching, and then boom! They just popped out.”
The images uncovered by Sand were taken for the DECam Legacy Survey (DECaLS), one of three public surveys, known as the DESI Legacy Imaging Surveys [1], that jointly imaged 14,000 square degrees of sky to provide targets for the ongoing Dark Energy Spectroscopic Instrument (DESI) Survey. DECals was conducted using the 570-megapixel Department of Energy-fabricated Dark Energy Camera (DECam), mounted on the U.S. National Science Foundation (NSF) Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, a Program of NSF NOIRLab.
The Sculptor galaxies, as they are referred to in the paper, are among the first ultra-faint dwarf galaxies found in a pristine, isolated environment free from the influence of the Milky Way or other large structures. To investigate the galaxies further, Sand and his team used the Gemini South telescope, one half of the International Gemini Observatory, partly funded by the NSF and operated by NSF NOIRLab. The results from their study are presented in a paper appearing in The Astrophysical Journal Letters, as well as at a press conference at the AAS 245 meeting in National Harbor, Maryland.
Gemini South’s Gemini Multi-Object Spectrograph (GMOS) captured all three galaxies in exquisite detail. An analysis of the data showed that they appear to be empty of gas and contain only very old stars, suggesting that their star formation was stifled a long time ago. This bolsters existing theories that ultra-faint dwarf galaxies are stellar ‘ghost towns’ where star formation was cut off in the early Universe.
This is exactly what astronomers would expect for such tiny objects. Gas is the crucial raw material required to coalesce and ignite the fusion of a new star. But ultra-faint dwarf galaxies just have too little gravity to hold onto this all-important ingredient, and it is easily lost when they are buffeted by the dynamic Universe they are part of.
But the Sculptor galaxies are far from any larger galaxies, meaning their gas could not have been removed by giant neighbors. An alternative explanation is an event called the Epoch of Reionization — a period not long after the Big Bang when high-energy ultraviolet photons filled the cosmos, potentially boiling away the gas in the smallest galaxies. Another possibility is that some of the earliest stars in the dwarf galaxies underwent energetic supernova explosions, emitting ejecta at up to 35 million kilometers per hour (about 20 million miles per hour) and pushing the gas out of their own hosts from within.
If reionization is responsible, these galaxies would open a window into studying the very early Universe. “We don’t know how strong or uniform this reionization effect is,” explains Sand. “It could be that reionization is patchy, not occurring everywhere all at once. We’ve found three of these galaxies, but that isn’t enough. It would be nice if we had hundreds of them. If we knew what fraction was affected by reionization, that would tell us something about the early Universe that is very difficult to probe otherwise.”
“The Epoch of Reionization potentially connects the current day structure of all galaxies with the earliest formation of structure on a cosmological scale,” says Martin Still, NSF program director for the International Gemini Observatory. “The DESI Legacy Surveys and detailed follow-up observations by Gemini allow scientists to perform forensic archeology to understand the nature of the Universe and how it evolved to its current state.”
To speed up the search for more ultra-faint dwarf galaxies, Sand and his team are using the Sculptor galaxies to train an artificial intelligence system called a neural network to identify more. The hope is that this tool will be able to automate and accelerate discoveries, offering a much vaster dataset from which astronomers can draw stronger conclusions.
Notes
[1] The DESI Legacy Imaging Surveys data are served to the astronomical community via the Astro Data Lab at NSF NOIRLab’s Community Science and Data Center (CSDC).
More information
This research was presented in a paper entitled “Three Quenched, Faint Dwarf Galaxies in the Direction of NGC 300: New Probes of Reionization and Internal Feedback” to appear in The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/ad927c
The team is composed of David J. Sand (University of Arizona), Burçin Mutlu-Pakdil (Dartmouth College), Michael G. Jones (University of Arizona), Ananthan Karunakaran (University of Toronto), Jennifer E. Andrews (International Gemini Observatory/NSF NOIRLab), Paul Bennet (Space Telescope Science Institute), Denija Crnojević (University of Tampa), Giuseppe Donatiello (Unione Astrofili Italiani), Alex Drlica-Wagner (Fermi National Accelerator Laboratory, Kavli Institute for Cosmological Physics, University of Chicago), Catherine Fielder (University of Arizona), David Martínez-Delgado (Unidad Asociada al CSIC), Clara E. Martínez-Vázquez (International Gemini Observatory/NSF NOIRLab), Kristine Spekkens (Queen’s University), Amandine Doliva-Dolinsky (Dartmouth College, University of Tampa), Laura C. Hunter (Dartmouth College), Jeffrey L. Carlin (AURA/Rubin Observatory), William Cerny (Yale University), Tehreem N. Hai (Rutgers, the State University of New Jersey), Kristen B.W. McQuinn (Space Telescope Science Institute, Rutgers, the State University of New Jersey), Andrew B. Pace (University of Virginia), and Adam Smercina (Space Telescope Science Institute)
NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.
The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag (Kitt Peak) to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.
Cosmoview Episode 93: DECam and Gemini South Discover Three Tiny ‘Stellar-
Ghost-Town’ Galaxies (VIDEO)
Links
- Read the paper: Three Quenched, Faint Dwarf Galaxies in the Direction of NGC 300: New Probes of Reionization and Internal Feedback
- DESI Legacy Imaging Surveys
- Photos of the Gemini South telescope
- Videos of the Gemini South telescope
- Images taken with GMOS-S
- Images of GMOS-S
- Photos of the Víctor M. Blanco 4-meter Telescope
- Videos of the Víctor M. Blanco 4-meter Telescope
- Photos of DECam
- Images taken by DECam
- Check out other NOIRLab Science Releases
Journal
The Astrophysical Journal Letters
DOI
SwRI’s Lisa Upton awarded prestigious solar physics prize
AAS/SPD Karen Harvey Prize recognizes significant contributions by early career scientists
SAN ANTONIO — January 15, 2025 —Southwest Research Institute’s Dr. Lisa Upton has received the 2025 Karen Harvey Prize from the American Astronomical Society’s Solar Physics Division, which recognizes the outstanding contributions made by early career solar scientists. Upton was honored for advancing our understanding of the Sun and exceptional leadership in the solar science community.
“This honor is well deserved. Dr. Upton’s talent and enthusiasm have had a major impact on the field, both directly through her publications and indirectly through organizing and motivating other scientists,” said SwRI’s Dr. Craig DeForest, director of SwRI’s Solar and Heliophysics Department.
Upton’s contributions to a state-of-the-art solar surface flux transport model have advanced our understanding of the solar corona, or outer atmosphere, and improved solar cycle predictions about when the Sun will be the most active. In particular, she is interested in advancing Sun-Earth system research, bridging the solar interior with its atmosphere and using her model to improve space weather predictions and ultimately mitigate effects on space-based technology and astronauts. She is a leading advocate for a solar polar mission.
“I am honored and delighted to receive the AAS/SPD's 2025 Harvey prize! Heliophysics — the study of the Sun and all that it touches — is a truly fascinating area of research because there is so much to learn and discover,” said Upton, a lead scientist in SwRI’s Solar System Science and Exploration Division, located in Boulder, Colorado. “The Sun’s polar regions are among the last regions in our solar system to be fully explored. Just as images from above the poles of Jupiter and Saturn revealed stunning surprises, we expect that the Sun’s poles will have some beautiful secrets to unveil. Getting there is a challenge, but certainly achievable in the next decade.”
Upton received her Ph.D. in Physics from Vanderbilt University in 2014. She has published over 34 papers in peer-reviewed journals, is included on over 100 presentation abstracts and has served on numerous national and international committees. She also served as co-chair to the NASA/NOAA Solar Cycle 25 Prediction Panel.
Passionate about science education and outreach, Upton hosts a website, solarcyclescience.com, to share her knowledge about the Sun and its impact on our planet with the general public and scientists alike. She also mentors undergraduates, graduate students and postdocs, and serves as a role model for women in science, technology, engineering and mathematics, or STEM, fields.
The prize is named in honor of solar physicist Karen Harvey and awarded annually by the AAS Solar Physics Division, with emphasis on an individual’s research excellence and potential. The 2025 Harvey Prize will be presented at SPD’s 56th meeting, jointly with the AAS and the Laboratory Astrophysics Division, June 8-12, 2025, in Anchorage, Alaska.
For more information, visit https://www.swri.org/heliophysics.
No comments:
Post a Comment