Magnetic fields may be the hidden force bringing both newborn stars and giant black holes together. New computer simulations suggest that magnetic fields play a crucial role in helping pairs of young stars form. The findings could explain why binary star systems are so common throughout the Milky Way and may even offer clues about [...]A distant quasar has revealed one of the most extreme ultraviolet outflows ever observed, providing new clues about the powerful interactions between supermassive black holes and their host galaxies. A supermassive black hole more than a billion times the mass of the Sun is blasting gas through space at such extraordinary speeds that astronomers are [...]A dark void once dismissed as cosmic dust may be a far more fascinating dance of black holes.
A new Keck Observatory study indicates that giant planets can spin faster than more massive brown dwarfs, revealing important clues about how planetary systems form and evolve. Astronomers have long suspected that a planet’s mass may be linked to how quickly it spins. In our solar system, Jupiter and Saturn rotate especially fast, each completing [...]NASA’s Roman Telescope could reveal 100,000 hidden worlds and rewrite what we know about planets across the Milky Way. NASA’s Nancy Grace Roman Space Telescope is expected to dramatically expand humanity’s catalog of worlds beyond our solar system. Known as exoplanets, these distant planets number nearly 6,300 discoveries so far through NASA missions and other [...]A star caught feeding on its companion has finally revealed the source of some of the galaxy’s most mysterious repeating signals. An international research team led by scientists at the University of Sydney has uncovered the strongest evidence yet explaining the origin of a puzzling type of cosmic signal. Their work has also revealed a [...]
NASA’s Fermi telescope may have finally uncovered the magnetic powerhouse behind the universe’s brightest supernovae. An international team of astronomers analyzing observations from NASA’s Fermi Gamma-ray Space Telescope has found what appears to be the first convincing detection of gamma rays from a rare type of extraordinarily bright stellar explosion known as a superluminous supernova. [...]
Occasionally I see references in Astronomy to the speed of something as “supersonic.” I’m having trouble reconciling this term with velocities typically found among astronomical objects. Wouldn’t “relativistic” be closer to the truth? Anything close to sonic speeds in Earth’s atmosphere wouldn’t cover much distance in outer space. Peter IanchiouTucson, Arizona One would certainly thinkContinue reading "What does the term ‘supersonic’ mean in astronomy?"
The post What does the term ‘supersonic’ mean in astronomy? appeared first on Astronomy Magazine.
Researchers say the isolated white dwarfs Gandalf and Moon-Sized define a new class of stellar remnant because they share five traits, including X-ray emission. Across the immense scale of the Universe, a single unusual object can prompt astronomers to look for others like it, sometimes leading to the recognition of an entirely new class of [...]A new method could improve cosmology research by analyzing supernovae together with the galaxies that host them. An international collaboration led by scientists at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) has created a new approach that may sharpen what researchers can learn about how the Universe expands and what dark [...]The James Webb Space Telescope (JWST) was designed to give us the ability to look at one of the earliest periods in the evolution of the Universe, a time when some of the earliest stars were putting out enough light to ionize the hydrogen that accounted for almost all of the normal matter present at the time. There were lots of ideas about what we might see, but the Universe is full of surprises.
One of the first surprises was the existence of what picked up the moniker "little red dots," which are exactly what their name suggests. After some initial arguments, it became clear that these were early versions of the supermassive black holes that presently sit at the center of almost every galaxy. Now, gravitational lensing has allowed astronomers to confirm that a little red dot is little more than a supermassive black hole without much in the way of a galaxy around it.
The little red dot in question is called Abell 2744−QSO1, and gravitational lensing has both magnified it and caused it to appear three times in the vicinity of the galaxy cluster that did the lensing. Based on details in its spectrum, we're looking at the object as it appeared just 700 million years after the Big Bang.
© NASA, ESA, CSA, Lukas Furtak, Alyssa Pagan
There are more opportunities to access space than ever, thanks to a bevy of commercial rockets, some with reusable boosters, led by SpaceX's workhorse Falcon 9. So why is NASA launching fewer telescopes and planetary science missions than it did a quarter-century ago?
The answer is complex. It is not necessarily the money. The space agency's science budget this year is $7.25 billion, roughly the same as it was in 2000, adjusted for inflation. This is despite attempts by the Trump administration to drastically reduce NASA science funding.
In the early months of his tenure, NASA Administrator Jared Isaacman's focus has been on human spaceflight and the Moon. This isn't terribly surprising given NASA's wildly successful Artemis II mission carrying four astronauts around the Moon last month. Since taking office in December, Isaacman has announced an overhaul of the Artemis program, canceling a space station to be built in orbit around the Moon in favor of construction of a base on the lunar surface.
© NASA/JPL-Caltech/Space Science Institute
The universe is around 14 billion years old, but scientists theorize that no stars formed for the first several hundred million years, during an era known as the cosmic dark ages. They refer to the first billion years or so after this, when stars formed, as the cosmic dawn. At that time, the very oldest galaxies first assembled from collections of gas and plasma.
As these galaxies assembled and more material became available, the number of stars formed each year increased. Around 2 to 3 billion years after the Big Bang, galaxies grew faster than they ever would, producing stars at the highest rate in the universe’s history. This era is called cosmic noon.
Researchers from the Netherlands recently investigated 3 distant galaxies whose light began its journey to Earth during cosmic noon. They selected targets from a set of ancient star-forming galaxies identified in the ALMA – Archival Large Program to Advance Kinematic Analysis or ALMA-ALPAKA project. Of these, they chose to study 3 galaxies labeled ID1, ID3, and ID13.
They combined 2 different types of data to produce a detailed description of these galaxies. First, they collected data from an enormous telescope comprising 66 antennas in Chile, known as the Atacama Large Millimeter/submillimeter Array or ALMA. They used ALMA to detect radio-wave emissions from carbon monoxide and elemental carbon in these galaxies. The researchers stated that studying these chemicals in distant galaxies could reveal how their free-floating gas clouds move. They also used publicly available data from JWST’s Near Infrared Camera, or NIRCam, to determine how much light the galaxies’ stars emitted. By analyzing cosmic noon galaxies in multiple different ways, the team aimed to measure their masses and the relative contributions of regular matter and dark matter.
They used a computer program developed by other astronomers to interpret the JWST data as a series of maps showing the distribution of stars across each galaxy. They used this light-emission data to estimate the total mass of all the stars in these galaxies. Then they developed an original computer program to map the distribution of gas through each galaxy using the ALMA data. The team used these maps to create plots, known as rotation curves, which show how fast particles orbit each galaxy’s center as a function of their distance from it.
The astronomers used these rotation curves to estimate the amount of dark matter in each galaxy. They explained that this method works because dark matter is totally invisible, but it still exerts a gravitational pull. Its gravitational pull causes visible material like stars and gas closer to the edges of these galaxies to move faster than they would in galaxies without dark matter.
The team found that these galaxies had between 39 and 80 billion times the mass of our sun, or solar masses, in stars. They had between 4 billion and nearly 16 billion solar masses worth of free-floating gas. And they had from 1 trillion to 31 trillion solar masses of dark matter.
However, when the team compared the light-emission data with the rotation curves, they found a discrepancy. Typically, dark matter resides in a shell or halo surrounding a galaxy, meaning it should mostly affect material near the galaxy’s outer edge. Since astronomers don’t usually have to account for dark matter near a galaxy’s center, they can calculate the total mass of center material based on the amount of gas and stars they see there. But near the centers of these galaxies, the team found that the masses they derived from the light emissions were less than what they calculated from the rotation curves.
They proposed multiple potential explanations for this discrepancy. First, they suggested that the halo shape might not be a good model for the dark matter distribution in all galaxies, meaning that cosmic noon galaxies could contain dark matter near their centers. Second, they suggested that stars could be packed tightly in the center of these galaxies, blocking each other’s light emissions. Third, they suggested that galaxy ID1 could have a supermassive black hole as big as 1.5% its total stellar mass at its center.
The team concluded that they now have a detailed picture of the mass distribution in these cosmic noon galaxies, but the reason for their center mass discrepancies remains elusive. They suggested that a complex relationship exists between the dark matter halos and the rest of the material within these galaxies. They indicated that future astronomers could adapt their methods to study the distribution of material in other distant galaxies studied by ALMA-ALPAKA and forthcoming galactic surveys.
The post Characterizing galaxies at “cosmic noon” appeared first on Sciworthy.
The Star Wars series depicted alien heroes fighting against evildoers and their planet-destroying superweapons “a long time ago in a galaxy far, far away.” But what do scientists really know about alien planets in distant galaxies beyond our own? These worlds, known as extragalactic exoplanets, are expected to exist, assuming the Milky Way is no different from other galaxies. However, we have yet to find them since other galaxies are still too far, far away for modern exoplanet-observing techniques.
Recently, a team of astronomers analyzed a stream of over 700,000 stars that the Milky Way likely absorbed from the dissolving Sagittarius dwarf galaxy. These stars are very distant, so the team investigated whether any of them host large, close-orbiting exoplanets called hot Jupiters, which are relatively easy to find.
They established a set of 3 criteria to narrow down their list of stars. First, each star should appear bright enough when observed by the Transiting Exoplanet Survey Satellite, or TESS, to ensure high-precision results from the team’s data processing software. Second, each star must have more than a 50% likelihood that it originated from the Sagittarius dwarf galaxy, based on motion and position measurements from the Gaia mission. Finally, each star should have a radius of less than twice the Sun’s, as it’s easier to find planets around smaller stars. They used these criteria to limit their candidate list to around 20,000 stars.
After selecting their candidate stars, the team analyzed publicly available TESS catalog data using the software packages eleanor and TESS-Gaia Light Curve, or TGLC. These tools allowed them to plot each star’s brightness over time, in graphs called light curves. Then, the astronomers looked for periodic brightness dips in these light curves as evidence that an exoplanet passed in front of the star. From this, they excluded several thousand additional stars with too much light interference from their surroundings, reducing their final sample size to just over 15,000 stars.
To find hot Jupiters, the team looked for brightness dips at intervals of 14 hours to 10 days, which is the typical orbital period range for hot Jupiters. Then, they used geometry to derive each exoplanet’s radius from the fraction of the starlight it blocked. They excluded candidates with dips corresponding to objects with radii at least twice that of Jupiter’s, as these are likely caused by orbiting companion stars rather than exoplanets.
Among all the stars they surveyed, the team’s strongest candidate to host a hot Jupiter was a star labeled TIC 92223525. They calculated that this star could host an exoplanet with a radius 1.76 times the size of Jupiter’s and an orbital period of 7.2 days. However, when they reviewed this star’s light curve, they found that it was likely contaminated by its neighbor, TIC 92223526. The regular brightness dips from this system of orbiting stars mimicked that of an exoplanet, creating a false positive for TIC 92223525 that was difficult to detect during initial screening. As a result, the team ultimately excluded this candidate, leaving them with no confirmed exoplanets.
The researchers drew several conclusions from their inability to find hot Jupiters in their sample of stars from the Sagittarius dwarf stream. They estimated that if more than 1% of these stars hosted hot Jupiters, it would have been highly unlikely not to detect one in a sample of over 15,000 stars. This places an upper limit of about 1% on the occurrence rate of hot Jupiters. If this estimate is accurate, then even an ideal exoplanet search team would need to examine over 11,000 stars to find an extragalactic hot Jupiter. Accounting for more realistic levels of scientific uncertainty, a future team would likely need to study at least 80,000 stars to find one.
Although this survey of the Sagittarius dwarf stream yielded null results, the team suggested that future researchers continue searching it and other star streams from different galaxies. Scientists have identified over 20 such streams in the Milky Way. Researchers studying these streams could find the first extragalactic exoplanet or provide evidence that other galaxies produce fewer hot Jupiters than our own. But let’s hope none of them find the first extragalactic Death Star!
The post Searching for planets in a galaxy far away appeared first on Sciworthy.
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