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The uniforms, revealed during a conference in Maryland this week, feature a dark navy coat, grey pants and six buttons, which symbolizes the Space Force being the sixth branch of the U.S. military, according to the Space Force’s Chief of Space Operations, Gen. John Raymond.
Lt. Col. Alison Gonzalez, the Space Force deputy chief of strategy, was one of the Guardians who modeled the new uniform. Gonzalez told Millitary.com she helped test the uniforms, ensuring they were designed with women in mind.
However, the fit of the pants might need a bit of work.
Several people on Twitter had some ideas:
If you’re not quite on board with the new uniform design, this video from BSG will help get you in the mood:
https://www.universetoday.com/152664/these-are-the-new-space-force-uniforms-so-say-we-all/feed/0152664A Proposed Clockwork Solar System Made out of LEGO
https://www.universetoday.com/152666/a-proposed-clockwork-solar-system-made-out-of-lego/#respondThu, 23 Sep 2021 13:28:15 +0000https://www.universetoday.com/?p=152666One of the best innovations Lego has had in the last decade is leveraging the power of the internet to help choose what kits to create.Â Innovative designers can buy piece parts, make their own masterpieces, carefully document how to recreate them, and then lobby Lego to release them at a kit.Â One of the …
]]>One of the best innovations Lego has had in the last decade is leveraging the power of the internet to help choose what kits to create.Â Innovative designers can buy piece parts, make their own masterpieces, carefully document how to recreate them, and then lobby Lego to release them at a kit.Â One of the more creative recent projects is a Clockwork Solar System designed by Chris Orchard and Brent Waller, and it is absolutely stunning.
At around 3000 pieces and measuring 52cm x 44 cm x 56 cm, their creation is on the larger side of Lego projects.Â But, it is surprisingly precise, with the project creators claiming that the orbital timing of the planets is 99.8% accurate to how they are in real life.
That level of accuracy results from hours of design and a whole lot of testing, totaling 15 months of work.Â Technic, the Lego system that includes gears, axles, and motors, allows the system to move accurately but is almost some of the most challenging types of LEGO to build.Â In addition, each planet has a unique model to represent it, and the clockwork system is brilliantly displayed in an accompanying video the project creators released.
They will need more than a fancy video and a well-written proposal to bring this project to fruition, though. A project needs 10,000 votes on the Lego IDEAS platform to get on the companyâs radar for an âExpert Review.â If the reviewers give it the go-ahead, the company could adopt the idea into a kit of its own.
Luckily, the project started strong.Â Having only been released three weeks ago, it already has over 7000 supporters as of the time of writing, and almost two full years to collect the next 3000 supporters needed to get it to that review.Â With that level of support and the amount of time left, the Clockwork Solar System is a shoo-in to at least get reviewed by the company.Â If it passes inspection, space enthusiasts everywhere can look forward to having it in their hands soon.
]]>https://www.universetoday.com/152666/a-proposed-clockwork-solar-system-made-out-of-lego/feed/0152666Astronomers Discover an Intermediate-Mass Black Hole as it Destroys a Star
https://www.universetoday.com/152627/astronomers-discover-an-intermediate-mass-black-hole-as-it-destroys-a-star/#respondWed, 22 Sep 2021 23:06:44 +0000https://www.universetoday.com/?p=152627Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find. Astronomers have spotted an intermediate-mass black hole destroying a star …
]]>Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find.
Astronomers have spotted an intermediate-mass black hole destroying a star that got too close. They’ve learned a lot from their observations and hope to find even more of these black holes. Observing more of them may lead to understanding how SMBHs got so massive.
When a star gets too close to a powerful black hole, a tidal disruption event (TDE) occurs. The star is torn apart and its constituent matter is drawn to the black hole, where it gets caught in the hole’s accretion disk. The event releases an enormous amount of energy, outshining all the stars in the galaxy for months, even years.
That’s what happened with TDE 3XMM J215022.4-055108, which is more readily known as TDE J2150. Astronomers were only able to spot the elusive IMBH because of the burst of x-rays emitted by the hot gas from the star as it was torn apart. J2150 is about 740 million light-years from Earth in the direction of the Aquarius constellation. Now a team of researchers has used observations of the distant J2150 and existing scientific models to learn more about the IMBH.
IMBHs are elusive and difficult to study. Astronomers have found several of them in the Milky Way and in nearby galaxies. Mostly they’ve been spotted because of their low-luminosity active galactic nuclei. In 2019 the LIGO and Virgo gravitational wave observatories spotted a gravitational wave from the merger of two IMBHs. As it stands now, there’s a catalogue of only 305 IMBH candidates, even though scientists think they could be common in galactic centers.
One of the problems in seeing them is their low mass itself. While SMBHs can be found by observing how their mass affects the stellar dynamics of nearby stars, IMBHs are typically too small to do the same. Their gravity isn’t powerful enough to change the orbits of nearby stars.
“The fact that we were able to catch this black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible,” saidÂ Ann Zabludoff, UArizona professor of astronomy and co-author on the paper. “Not only that, by analyzing the flare we were able to better understand this elusive category of black holes, which may well account for the majority of black holes in the centers of galaxies.”
It was the eruption of x-rays that made the event visible. The team compared the observed x-rays with models and was able to confirm the presence of an IMBH. “The X-ray emissions from the inner disk formed by the debris of the dead star made it possible for us to infer the mass and spin of this black hole and classify it as an intermediate black hole,” lead author Wen said.
This is the first time that observations have been detailed enough to be able to use a TDE flare to confirm the presence of an IMBH. It’s a big deal, because though we know that SMBHs lie in the center of galaxies like the Milky Way and larger, our understanding of smaller galaxies and their IMBHs is much more limited. They’re just really hard to see.
“We still know very little about the existence of black holes in the centers of galaxies smaller than the Milky Way,” said co-author Peter Jonker of Radboud University and SRON Netherlands Institute for Space Research, both in the Netherlands. “Due to observational limitations, it is challenging to discover central black holes much smaller than 1 million solar masses.”
The mystery surrounding IMBHs feeds into the mystery surrounding SMBHs. We can see SMBHs at the heart of large galaxies, but we don’t know exactly how they got that massive. Did they go through mergers? Maybe. Through the accretion of matter? Maybe. Astrophysicists mostly agree that both mechanisms may play a role.
Another question surrounds SMBH “seeds.” The seeds could be IMBHs of tens or hundreds of solar masses. The IMBHs themselves could’ve grown from stellar-mass black holes that grew into IMBHs through the accretion of matter. Another possibility is that long before there were actual stars, there were large gas clouds that collapsed into quasi-stars, that then collapsed into black holes. These strange entities would collapse directly from quasi-star to black hole without ever becoming a star, and are known as direct collapse black holes. But these are all hypotheses and models. Astrophysicists need more actual observations, like in the case of TDE J2150, to confirm or rule anything out.
“Therefore, if we get a better handle of how many bona fide intermediate black holes are out there, it can help determine which theories of supermassive black hole formation are correct,” Jonker said.
The team of researchers was also able to measure the black hole’s spin, which has implications for black hole growth, and maybe for particle physics, too. The black hole is spinning quickly, but it’s not spinning as fast as possible. It begs the question, how did the IMBH attain a speed in this range? The spin opens up some possibilities and eliminates others.
“It’s possible that the black hole formed that way and hasn’t changed much since, or that two intermediate-mass black holes merged recently to form this one,” Zabludoff said. “We do know that the spin we measured excludes scenarios where the black hole grows over a long time from steadily eating gas or from many quick gas snacks that arrive from random directions.”
The spin rate may shed some light on potential particle candidates for dark matter, too. One of the hypotheses says that dark matter is made up of particles never seen in a laboratory, called ultralight bosons. These exotic particles, if they exist, would have less than one-billionth the mass of an electron. The IMBHs spin rate may preclude the existence of these candidate particles.
“If those particles exist and have masses in a certain range, they will prevent an intermediate-mass black hole from having a fast spin,” co-author Nicholas Stone said. “Yet J2150âs black hole is spinning fast. So, our spin measurement rules out a broad class of ultralight boson theories, showcasing the value of black holes as extraterrestrial laboratories for particle physics.”
This discovery will build toward a better understanding of dwarf galaxies and their black holes, too. But for that to happen, astrophysicists need to observe more of these IMBH tidal disruption events.
“If it turns out that most dwarf galaxies contain intermediate-mass black holes, then they will dominate the rate of stellar tidal disruption,” Stone said. “By fitting the X-ray emission from these flares to theoretical models, we can conduct a census of the intermediate-mass black hole population in the universe,” Wen added.
As is often the case in astronomy, astrophysics, and cosmology, future telescopes and observatories should advance our knowledge considerably. In this, the Vera C. Rubin Observatory could play a role. The Rubin could discover thousands of TDEs each year.
Then we may finally be able to piece together the story of not only IMBHs but also SMBHs.
]]>https://www.universetoday.com/152627/astronomers-discover-an-intermediate-mass-black-hole-as-it-destroys-a-star/feed/01526273,600 Years ago, a 50-Meter-Wide Meteor Exploded in the Sky and Destroyed a City Near the Dead Sea
https://www.universetoday.com/152645/3600-years-ago-a-50-meter-wide-meteor-exploded-in-the-sky-and-destroyed-a-city-near-the-dead-sea/#respondWed, 22 Sep 2021 20:17:20 +0000https://www.universetoday.com/?p=152645An archeological dig has uncovered evidence of a massive cosmic airburst event approximately 3,600 years ago that destroyed an entire city near the Dead Sea in the Middle East. The event was larger than the famous Tunguska airburst event in Russia in 1908, with a blast 1,000 times more powerful than the Hiroshima atomic bomb. …
]]>An archeological dig has uncovered evidence of a massive cosmic airburst event approximately 3,600 years ago that destroyed an entire city near the Dead Sea in the Middle East. The event was larger than the famous Tunguska airburst event in Russia in 1908, with a blast 1,000 times more powerful than the Hiroshima atomic bomb. The event flattened the thriving city of Tall el-Hammam, located in what is now Jordan.
Using evidence unearthed in the dig along with an online impact calculator, the researchers estimate a space rock approximately 50 meters wide exploded about 4 km (2.5 miles) above the Earth, sending a blinding flash and a wave of heat at 2,000 degrees (3,600 F). This would have immediately incinerated wood structures and bodies, and melted any metal objects like swords or spears, and even pottery and mudbrick structures.
But the destruction wasnât over. A few seconds later, a massive shockwave leveled everything, including a 4-to-5-story palace complex and a large 4-m-thick mudbrick fortification wall.
The authors of the paper, published in Nature Scientific Reports, say that although this doesnât fall into their area of expertise, âan eyewitness description of this 3600-year-old catastrophic event may have been passed down as an oral tradition that eventually became the written biblical account about the destruction of Sodom.â Sodom was the city, which, according to biblical texts, was destroyed for its lecherousness, with stones and fire falling from the sky. However, this story originates from a time when many natural disasters were blamed on the anger of the gods.
In many sites in the Middle East, archeological digs or studies reveal several layers of past habitation that have religious or nationalist significance for more than one ethnic group, where the victor of wars or conquests built upon the ruins of the city or buildings it just conquered â with the cycle repeating over the millenniums.
The region around Tall el-Hammam is different however, in that since the end of the Middle Bronze Age, this region in eastern Jordan suffered some sort of civilization-ending calamity, and remained unoccupied for the next five-to-seven hundred years. Additionally, this area was originally one of the most productive agricultural lands in the region, and which had supported flourishing civilizations continuously for at least 3,000 years. But suddenly the soil in the region was inundated with salts where nothing would grow.
This mystery is being investigated by researchers from multiple universities and organizations and archeologists have been working at the Tall el-Hammam site since 2005. Even the earliest archaeological excavations revealed the presence of unusual materials, including melted mudbrick fragments, melted pottery, ash, charcoal, charred seeds, and burned textiles, all intermixed with pulverized mudbrick. Additionally, further digs revealed incredible destruction.
The researchers eliminated the usual suspects, such as warfare, fires, volcanic eruption, or earthquakes because these events were unlikely to cause the kind of destruction they found at the site, and none of those events could have produced the intense heat required to cause the melting that they found. Â But then the excavators found spherules of shocked quartz, a tell-tale sign of an intense and sudden high-temperature event such as a cosmic impact.
âAfter eleven seasons of excavations, the site excavators independently concluded that evidence pointed to a possible cosmic impact,â the team wrote in their paper. âThey contacted our outside group of experts from multiple impact-related and other disciplines to investigate potential formation mechanisms for the unusual suite of high-temperature evidence.â
While an asteroid impact could have created all the evidence found by the archaeologists, that type of event was dismissed because there was no evidence of a crater in the area.
Using an impact calculator, a group of 21 researchers determined the most likely cause of the destruction was a cosmic air burst caused by a comet or meteor. Their calculations showed such an event would result in the unusal destruction found by archaeologists, such as pottery sherds with outer surfaces melted into glass, some bubbled as if they were boiled, mudbrick fragments and âextreme disarticulation and skeletal fragmentation in nearby humans.â
Also, an airburst-related influx of salt produced hypersalinity in the surrounding soil, making agriculture impossible, causing a 600-year-long abandonment of about 120 regional settlements within a 25-km radius.
âWe think the explosion may have vaporized or splashed toxic levels of Dead Sea salt water across the valley,â wrote a group of research collaborators in an article in The Conversation (archaeologist Phil Silvia, geophysicist Allen West, geologist Ted Bunch and space physicist Malcolm LeCompte). âWithout crops, no one could live in the valley for up to 600 years, until the minimal rainfall in this desert-like climate washed the salt out of the fields.â
]]>https://www.universetoday.com/152645/3600-years-ago-a-50-meter-wide-meteor-exploded-in-the-sky-and-destroyed-a-city-near-the-dead-sea/feed/0152645A Particle Physics Experiment Might Have Directly Observed Dark Energy
https://www.universetoday.com/152615/a-particle-physics-experiment-might-have-directly-observed-dark-energy/#commentsWed, 22 Sep 2021 18:10:54 +0000https://www.universetoday.com/?p=152615In a new study, a team of researchers proposed that Dark Matter detectors could also search for the elusive force that is causing our Universe to expand (Dark Energy)!
]]>About 25 years ago, astrophysicists noticed something very interesting about the Universe. The fact that it was in a state of expansion had been known since the 1920s, thanks to the observation of Edwin Hubble. But thanks to the observations astronomers were making with the space observatory that bore his name (the Hubble Space Telescope), they began to notice how the rate of cosmic expansion was getting faster!
This has led to the theory that the Universe is filled with an invisible and mysterious force, known as Dark Energy (DE). Decades after it was proposed, scientists are still trying to pin down this elusive force that makes up about 70% of the energy budget of the Universe. According to a recent study by an international team of researchers, the XENON1T experiment may have already detected this elusive force, opening new possibilities for future DE research.
Both DM and DE are part of the Lambda Cold Dark Matter (LCDM) model of cosmology, which posits that the Universe is filled with cold, slow-moving particles (DM) that interact with normal matter via the force of gravity alone. The Lambda represents DE, which is accelerating the expansion of the Universe. Since they are only discerned by observing their effect on the large-scale structure of the Universe, conventional thinking has it that neither force interacts with normal matter via electromagnetism or the weak or strong nuclear force.
However, some DM theories posit that there is some level of interaction with visible matter, which researchers are actively testing. However, in lieu of more test results, astrophysicists and cosmologists remain unclear about how DE fits in with the physical laws that govern the Universe. So far, candidates include a modification of Einstein’s General Relativity (GR), the presence of a new field, or a Cosmological Constant (CC). As Dr. Visinelli told Universe Today via email:
“For this reason, dark energy is possibly even more mysterious than dark matter. We see the effects of dark energy through a number of observations, starting from the seminal work on the supernovae 1A as standard candles.Assuming dark energy is indeed a field, the quanta associated with it would be extremely light and carry very little energy. This is the reason why very little work has been devoted to these types of searches.”
Their work is based on new research that looks beyond the standard LCDM model of cosmology to consider that DE interacts with light by affecting its properties (i.e., polarization, color, direction). However, these interactions could be subject to screening mechanisms that prevent local experiments from detecting them. In this model, it is predicted that dark energy quanta can be produced in the Sun.
As Dr. Vagnozzi explained, the possible connection between screening and dark energy first came to him as he was showering one day:
“I remember it was June 20 and I was having a shower and pondering about solar axions (not) explaining XENON, and I realized the obvious way out was screening, as it would shut down production in denser stars. Screening is usually associated to models of dark energy and/or modified gravity, and there was the ‘click.‘
“I immediately Whatsapped Luca and we started working on this straight away (and contacted our other co-authors who are experts on screened dark energy/modified gravity models).”
For the sake of their study, the team led by Dr. Vagnozzi and Dr. Visinelli considered the data released by the XENON collaboration, a DM research team made up of 135 investigators from 22 institutions around the world. At the heart of their experiment is a 3,500 kg (7,715 lbs) detector of ultra radio-pure liquid xenon housed within a 10 m (32.8 ft) water tank. Located at the INFN Laboratori Nazionali del Gran Sasso, XENON is also the most sensitive Dark Matter (DM) experiment ever performed.
In 2020, the Collaboration published the results of their experimental run (2016 to 2018), which showed an unexpected rate of electron recoil events. According to the collaboration, this did not constitute a DM detection but could be explained by a tiny residual amount of tritium in the experiment, the existence of a new particle (such as the solar axion), or an unexplained property in neutrinos.
For the sake of their study, however, the team led by Vagnozzi and Visinelli theorized that it may have been the first direct detection of DE. Said Vagnozzi:
“In our model, dark energy possesses peculiar properties: its mass term is related to the density of the environment, so that the denser materials would shield the effects of dark energy, while lighter environments such as the intergalactic space would allow a long-range of the dark energy.
“In this model called âchameleonâ, quanta of dark energy are produced in the region of the Sun in which the electromagnetic field is the strongest, the tachocline, which is the region in which the transport of the energy inside the Sun transitions from radiative to convective. The high energy density in electromagnetic radiation in the region allows for a strong coupling with the chameleon field and to its production.”
If true, this would mean that experiments worldwide that are currently geared towards Dark Matter research could also be dedicated to the hunt for Dark Energy. To this end, Dr. Vagnozzi and Dr. Visinelli hope that this study sparks interest in the particle models of DE and that the search for these elusive particles can be carried out in parallel with the ongoing search for DM.
Even if these experiments are ultimately unsuccessful, they would at least be able to test theories about DE that range beyond the LCDM model, helping scientists to narrow the list of candidates:
“Many other experiments designed for Dark Matter can also carry information about these chameleons, and we hope that designing future setups for these searches will be envisioned. An independent test using cosmological data crossed with the predictions from the chameleon model would also be needed. As for us, we plan to refine the computations in our paper by using a solar model, study the production of chameleons in massive stars, and get in contact with experimentalists for updates.”
In a recent paper, Dr. Vagnozzi and Dr. Visinelli conducted a study to examine whether pure elastic scattering between dark energy and baryonic (aka. normal) matter could leave a visible imprint in cosmological observations. They determined that this was not likely, at least when applied to observations that are sensitive to the linear evolution of the cosmic structure, such as the Cosmic Microwave Background (CMB) and the clustering of the large-scale structure at the linear level.
Dr. Visinelli is also working with a Ph.D. student in Munich now to develop the theory further. Specifically, they are hoping to predict the implications that interactions between DE and visible matter would have for the large-scale structure of the Universe. Coupled with DE and DM surveys, which will benefit from next-generation telescopes in the coming years, astronomers and cosmologists could be on the verge of shining light on the “Dark Universe”!
]]>https://www.universetoday.com/152615/a-particle-physics-experiment-might-have-directly-observed-dark-energy/feed/1152615NASA has a Ballistic air gun to Hurl Rocks at Space Suits to Test Their Micrometeorite Protection
https://www.universetoday.com/152651/nasa-has-a-ballistic-air-gun-to-hurl-rocks-at-space-suits-to-test-their-micrometeorite-protection/#respondWed, 22 Sep 2021 14:40:53 +0000https://www.universetoday.com/?p=152651Shock testing is commonly used throughout engineering to determine how a product will do when impacted by something.Â That something could be anything from the ground to a cruise missile.Â Like so much else in space exploration, engineers at NASA are performing the same type of test, just scaled up.Â Instead of simply dropping the …
]]>Shock testing is commonly used throughout engineering to determine how a product will do when impacted by something.Â That something could be anything from the ground to a cruise missile.Â Like so much else in space exploration, engineers at NASA are performing the same type of test, just scaled up.Â Instead of simply dropping the object under test, as is common in most settings, they shoot it with a steel ball going 3000 ft/second.
Researchers at the Ballistics Impact Lab use a 40-foot-long gun to simulate what it would be like to be hit by a micrometeorite in space.Â Recently, the team has focused on testing different types of fabric for use in space suits.Â A rapid decompression from a micrometeorite strike anywhere on a suit would be fatal to any astronaut unlucky enough to suffer one.Â Â
Understanding how a piece of fabric would fail in such a situation is critical to improving its design.Â Some forms of failure are worse than others. The lab has a series of high-speed cameras and sensors surrounding the material under test to ensure it can capture as much data about those failure modes as possible.Â Â
Those failure modes can be caused by more than just steel balls.Â A different test rig shoots a piece of simulated moon rock (primarily made of basalt) vertically down onto the fabric.Â Also, the fabric isnât the only material that has to undergo such testing – other material that could be used on the exterior of habitats, or even material specifically designed to capture space debris, must also undergo similar violent testing.
Such testing will continue, using a combination of resources from the Glenn Research Center, where the physical lab is located, and Johnson Space Center, where the data is analyzed.Â As maintaining a tight seal between the external void and the soft human inhabiting the suits and habitats of the Moon becomes more critical, violently testing the materials that make those seals out of does so as well.
]]>https://www.universetoday.com/152651/nasa-has-a-ballistic-air-gun-to-hurl-rocks-at-space-suits-to-test-their-micrometeorite-protection/feed/0152651Using Quasars as a New Standard Candle to Define Distance
https://www.universetoday.com/152621/using-quasars-as-a-new-standard-candle-to-define-distance/#commentsWed, 22 Sep 2021 13:36:21 +0000https://www.universetoday.com/?p=152621A new study shows a way to gauge distance in the early Universe.
]]>A new study shows a way to use quasars to gauge distance in the early Universe.
The simple question of âhow far?â gets at the heart of the history of modern astronomy. Looking out across our galactic backyard into the primordial Universe, different yardsticksâoften referred to as âstandard candlesâ âare used to gauge various distances, from near to far.
Now, astronomers may have another tool in their Universe-measuring arsenal. A recent study out of the Center for Astrophysics (CfA) looked at X-ray measurements of 2332 quasars in the Chandra Source Catalog compiled by NASAâs prolific Chandra X-ray telescope, versus their luminosity in the ultraviolet as seen in the Sloan Digital Sky Survey. The team found a tight correlation between the two factors… a correlation that extends back to quasars in the early Universe.
âWe see a relation between X-ray and UV luminosities. This relation is well known and has been used for many years,â Astrophysicist Francesca Civano (Center for Astrophysics, Harvard & Smithsonian) told Universe Today. âRecent studies by Risaliti, Lusso and collaborators find that the relation does not evolve with redshift and therefore we can use the same relation just using fluxes and use it to compute the distance of the objects.â
Whatever quasars are, theyâre an exotic feature of the early Universe that we donât see in the nearby cosmos today. The first quasar discovered was 3C 273 in 1963. With a high redshift (z=0.158) astronomers knew they were looking at something extremely distant and therefore intrinsically luminous. To give you some idea just how bright 3C 273 actually is, it has an absolute magnitude value of -27. That is, if you placed it at a distance of 10 parsecs away, it would compete with the Sun in the sky (and spell a bad day for the Earth if it were that close!)
The first ârungâ on the cosmic distance ladder is parallax, using observations from two different points in space and basic trigonometry to gauge distance. Using the Earthâs orbit as a baseline is also the basis for the parsec whichâdespite what Han Solo will tell you in a Mos Eisley Cantinaâis a measure of distance, 3.26 light-years long.
But parallax will only get you so far. The next yardstick out was discovered by astronomer Henrietta Swan Levitt while examining variable stars in the Small Magellanic cloud in 1912. She noticed that a particular type of star known as a Cepheid variable pulses in a fashion thatâs directly related to its luminosity. Find a Cepheid in a galaxy (as Hubble did in the Andromeda galaxy just over a decade later in 1923) and you can gauge its distance.
But for larger distances, brighter standard candles are needed. For these, astronomers use Type IA supernovae, as they flare and fade in a predictable fashion. Over the immense distances of hundreds of millions of light-years, cosmic expansion and spectroscopic redshift (noted as z) comes into play. This relation (known as Hubbleâs Law) correlates velocity as proportional to distance due to the expansion of the Universe: the higher the redshift, the more distant the object.
Type IA supernovae are good back to about three billion years after the Big Bang; quasars as standard candles proposed in the study would be good to just 700 million years after the Big Bang, a vast improvement.
Quasars have another advantage, as hundreds of thousands of them have been discovered in recent years. As a standard candle, they provide not only a good overlap with more distant Type 1A supernovae, but are also a good backup check for distance, as they are separately distinct cosmological processes.
Earthbound sky surveys to come, such as the Vera Rubin Observatory, and X-ray observatories already in space, such as NuSTAR and Chandra are bound to discover more quasars in the early Universe, putting their use as standard candles to the test.
âWe need to get better and better data, in particular in the x-rays to reduce the uncertainties on the X-ray flux measurement which is the one causing the most dispersion on the X-ray and UV relationship and therefore giving larger uncertainties on the distance measurement,â says Civano. âMoreover, it would be nice to have more quasars at low redshift so that the fitting to the cosmological parameters can become independent over the entire redshift range from supernovae.â
Catching a Quasar
You can, with a bit of skill and dark skies, observe quasar 3C 273 from your driveway with a good-sized telescope. At magnitude +12.9 it wonât look like much more than a nondescript faint starâ¦ but itâs amazing to think that youâre seeing photons that left their source 2.4 billion years ago (!) back in the Archean Eon on Earth, around the start of the Great Oxygenation Event.
The coordinates for 3C 273 are: Right Ascension (R.A.) 12H 29â 07,â Declination 02 degrees 03â 09â.
And to think, in just over half a century since discovery, quasars have gone from enigmatic objects to key standard candles for probing the early Universe.
Lead image: An artistâs impression showing the distant quasar P172+18 and its radio jets. Credit: The ESO.
]]>https://www.universetoday.com/152621/using-quasars-as-a-new-standard-candle-to-define-distance/feed/1152621By Using Dashcams and Security Cameras, Astronomers Were Able to Track Down the Location of a Meteorite
https://www.universetoday.com/152640/by-using-dashcams-and-security-cameras-astronomers-were-able-to-track-down-the-location-of-a-meteorite/#respondTue, 21 Sep 2021 20:17:54 +0000https://www.universetoday.com/?p=152640OK, all you meteorites that are falling to Earth â¦ You are being watched! The ever-expanding use of security cameras, doorbell cams and vehicle dashcams have increased the number of fireballs that have been spotted streaking across the skies. And sometimes, all that visual data provides the side benefit of allowing rocks from space to …
]]>OK, all you meteorites that are falling to Earth â¦ You are being watched!
The ever-expanding use of security cameras, doorbell cams and vehicle dashcams have increased the number of fireballs that have been spotted streaking across the skies. And sometimes, all that visual data provides the side benefit of allowing rocks from space to be tracked and found.
Back in February of 2020, hundreds of people across Slovenia, Croatia, Italy, Austria and Hungary reported seeing a bright ball of light hurtling across the morning sky, along with a loud explosion and a visible trail of dust in the sky. The event was captured by several cameras, including one that was on a cyclistâs helmet.
âBy combining observations from several cameras around 100 kilometers apart, a fireballâs position can be pinpointed to within 50 meters, and itâs usually fairly easy to compute its atmospheric trajectory and pre-atmospheric orbit this way,â said Dr. Denis Vida from the University of Western Ontario, who presented a paper on finding the meteorites at the Europlanet Science Congress (EPSC) 2021.
Vida and his colleagues estimate the initial stony object that streaked through the sky was about one meter across and weighed roughly four metric tons. But it broke apart into at least 17 pieces.
Three fragments amounting to 720 grams have been recovered and taken to laboratories for analysis. The largest fragment that was recorded falling in the videos has an estimated mass of about ten kilograms, but is yet to be found. Vida said it may have dropped into a muddy field and may have accidentally been plowed in before its fall area was known.
Vida said the pieces of the now-named Novo Mesto space rock — named after the Slovenian city near where the fragments were found — are ordinary chondrites, and the researchers are hoping to determine where in the Solar System it might have originated. Knowing where it came from could possibly reveal details of the asteroids from its original location, as well as about the early Solar System, the space rock was formed.
Vida said the fireballâs path is in an area where there are several all-sky cameras that specifically look for fireballs and meteors. However, this fireball occurred during the day when most of those cameras are turned off. Â Thatâs why footage recorded by the dashcams and security cameras were so important in locating the meteorites.
The researchers said this is one of only around 40 fallen space rocks that have been recovered within weeks of falling to Earth. Another famous fireball was the Chelyabinsk airburst in 2013, which was also recorded by dashcams and security cameras. A security camera caught the moment a chunk of that meteor hit a frozen lake, creating a 20-foot (6 meter) hole in the ice. Divers were able to fish out a 1/2 ton chunk of the Chelyabinsk meteorite that measured 5 feet long (1.5 meter). It broke into three pieces as scientists hoisted it into a scale to weigh it.
Lead image caption: A 48-gram piece of the Novo Mesto meteorite. Credit: Bojan AmbroÅ¾i? (Center of Excellence on Nanoscience and Nanotechnology, Slovenia and https://bojanambrozic.com/).