Astronomy

An experiment with a robot and gelatine determined that 65-micrometre-thick paper is the most prone to slicing our skin – but it can also make for a handy recyclable knife

New research suggests some stars at the very heart of the Milky Way may have found an alternative fuel in the form of annihilating dark matter that grants them immortality.

A group of high school astronomy students helped confirm and characterize a planet slightly smaller than Saturn that closely orbits its star.

The post High School Citizen Scientists Join the Hunt for Exoplanets appeared first on Sky & Telescope.

Mitochondria appear to ratchet up their activity when life is going well and tamp it down during hard times

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On 20 June 2024 the first Ariane 6 rocket to launch into space went through its last full ‘wet dress rehearsal’ at Europe’s Spaceport in French Guiana – it provided an exciting sneak peek of what’s to come, stopping just a few seconds before engine ignition and of course, liftoff.

One of the first steps was to roll back the colossal 90-m tall Ariane 6 mobile gantry building 120 m away from the launch pad – the first moment the complete rocket stood free.

The first parts of Ariane 6 began arriving in French Guiana from continental Europe in February 2024 via the Canopée ‘spaceship’. In March, the main stage and upper stage were assembled, followed by the transfer of the two powerful P120C boosters in April.

In May, Ariane 6’s first passengers also arrived in Kourou – a varied selection of experiments, satellites, payload deployers and reentry demonstrations that represent thousands across Europe, from students to industry and experienced space actors NASA and ArianeGroup.

The payloads were integrated onto the ‘ballast’ at the end of May, and just a few days ago the ballast was fitted onto the top of the rocket and the fairing closed around it – the last time Ariane 6’s cargo would see light.

From Earth observation to technology demonstrations testing wildlife tracking, 3D printing in open space, open-source software and hardware and science missions looking for the most energetic explosions in the universe, the passengers on Ariane 6’s first flight are a testament to the rocket’s adaptability, complexity, and its role for the future – launching any mission, anywhere.

An AI that can tell which chess moves are awe-inspiring is being used to make a chess computer that would play creatively, possibly making it more enjoyable to watch or compete against

An AI that can tell which chess moves are awe-inspiring is being used to make a chess computer that would play creatively, possibly making it more enjoyable to watch or compete against

A recent Supreme Court decision rules that the U.S. government can talk to scientists and social media companies to curb online falsehoods

The human brain loves seeing patterns, even when they aren’t really there

A neighbor galaxy of the Milky Way could offer fresh clues in the 90-year-long quest to determine the nature of dark matter.

Get a behind-the-scenes look at how researchers live and work on a U.S. icebreaker making its way through the waters of West Antarctica.

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Have you ever wondered what an impact crater looks like from space? Today, we’re counting down some of our favourite impact craters here on Earth – captured by Earth-observing satellites.

Craters are inevitably part of being a rocky planet. They occur on every planetary body in our solar system – no matter the size. By studying impact craters and the meteorites that cause them, we can learn more about the processes and geology that shape our entire solar system.

One proposal offers a unique method to directly image ExoEarths, or rocky worlds around nearby stars.

It’s the holy grail of modern exoplanet astronomy. As of writing this, the count of known worlds beyond the solar system stands at 6,520. Most of these are ‘hot Jupiters,’ large worlds in tight orbits around their host star. But what we’d really like to get a look at are ‘ExoEarths,’ rocky worlds (hopefully) like our own.

Now, a recent study out of the University of Paris, the European Southern Observatory (ESO) and the University of Cambridge entitled Exoplanets in Reflected Starlight with Dual-Field Interferometry: A Case For Shorter Wavelengths and a Fifth Unit Telescope at VLTI/Paranal suggests a method to do just that in the coming decade. This would involve one the most massive telescope complexes ever built: the Very Large Telescope. Based at Paranal Observatory in Chile, this array consists of four 8.2-metre telescopes working in concert via a method known as interferometry. The study advocates adding a fifth telescope, giving the VLT the capacity to see Jupiter-sized worlds shining directly in the host star’s light… and with a few key upgrades, the new and improved VLT could perhaps image ‘ExoEarths’ directly.

Pioneering Dual-Field Interferometry

Interferometry is the method of using superimposed waves collected from two telescopes to merge a signal into one image. This method allows for a resolution equivalent to the baseline between the two collecting instruments, bypassing the need for one enormous telescope. Long baseline radio interferometry can span continents, and there are plans to move the technique into space. Interferometry at visual wavelengths is a tougher proposition, one that’s just reaching its true potential.

Dual Field Interferometry uses the technique to simultaneously focus on two narrow fields in context within a larger field. One field is centered on the host star, and one on the target exoplanet. This can then minimize (subtract) photon shot noise from the primary, allowing for a clear view of the target world.

“With this technique, at the VLTI, we have a resolution equivalent to having a telescope of 130 meters,” lead author on the study Sylvestre Lacour (University of Paris) told Universe Today. “This allows us to distinguish the exoplanet’s light from the contamination by the stellar light, allowing to detect exoplanets very close to the star.”

ESO’s Very Large Telescope (VLT) timelapse of Beta Pictoris b around its parent star. This young massive exoplanet was initially discovered in 2008 using the NACO instrument at the VLT.  The sequence tracked the exoplanet from late 2014 until late 2016, using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) — another instrument on the VLT.

“The term ‘dual’ in dual interferometry comes from the fact the we are observing at the same time the exoplanet and the star with the optical interferometer,” says Lacour. “This is necessary to be able to probe at the same time the phase of the stellar light and the phase of the exoplanet light, to be able to distinguish the two. By ‘phase’ I mean the phase of the electric field entering the interferometer.”

The GRAVITY instrument at the VLTI in Paranal. Credit: ESO The Hunt for ExoEarths

The method is already being applied to reveal nearby worlds. “We typically observe exoplanets at a few tens of parsecs,” says Lacour. “They are massive exoplanets, more massive than Jupiter (between 4 and 10 Jupiter masses), and they are young, less than 50 million years (old). You can look for the results for the GRAVITY collaboration, operating the GRAVITY instrument at Paranal.”

One key technique used to overcome the effects of ‘shot noise’ is what’s termed as ‘apodization’. “Apodization is a way to decrease the contamination of the stellar light entering into our interferometer,” says Lacour. “It is similar to adding a coronagraph.”

Apodization makes ground-based systems such as the VLTI viable in terms of exoplanet science and direct detection. Other efforts such as the European Space Agency’s Proba-3 space telescope launching later in 2024 will use a free flying coronagraph to directly image exoplanets.

A pro to this method is it can characterize orbits within a few Astronomical Units from their host star. Other techniques observe planets very close in, or very far out. The downside of the method is that it’s a very difficult technique, right on the grim edge of what’s currently possible with existing telescopes.

An artist’s conception of the E-ELT telescope. Credit: Swinburne Astronomy Productions/ESO The Future of Exoplanet Astronomy

There’s already a good case for plans to extend the VLTI baseline to a fifth instrument. This includes direct imaging for worlds known orbiting around nearby stars to include Proxima Centauri B and Tau Ceti e. Lessons learned from the VLTI could also work for the Extremely Large Telescope, which may see first light in 2028.

An artist’s conception of Tau Ceti e, a possible ‘ExoEarth’ in the habitable zone. Ph03nix1986/Wikimedia Commons/CCA 4.0

It’ll be exciting to see more nearby worlds revealed by this technique in the coming decade.

The post Existing Telescopes Could Directly Observe ‘ExoEarths…’ with a Few Tweaks appeared first on Universe Today.

A survey of women who have had vaginal sex with men found that 4 in 5 said they had experienced pain during intercourse

A survey of women who have had vaginal sex with men found that 4 in 5 said they had experienced pain during intercourse

Image: Ahead of Asteroid Day, the Copernicus Sentinel-2 mission takes us over the Meteor Crater, also known as the Barringer Meteorite Crater.

Take off with ESA Impact! Ariane 6 and astronaut news await

Welcome to the 2024 second quarter edition of ESA Impact.

One of the most fundamental questions astronomers ask about an object is “What’s its distance?” For very faraway objects, they use classical Cepheid variable stars as “distance rulers”. Astronomers call these pulsating stars “standard candles”. Now there’s a whole team of them precisely clocking their speeds along our line of sight.

What makes a classical Cepheid a “standard candle” in the darkness of the Universe? It’s that pulsation. Not only does a Cepheid grow larger in a regular rhythm, but its brightness changes over predictable periods of time. In the early 1900s, astronomer Henrietta Leavitt studied thousands of these stars. She found something pretty interesting: there’s a strong relationship between a Cepheid’s luminosity and its pulsation period. And that’s a useful relationship.

When you compare a Cepheid’s luminosity to its pulsation period, you can derive the star’s distance. This relationship appears to be true for all known Cepheids. That’s why they’re considered an important part of the cosmic distance ladder. They’re the main benchmark for scaling the huge distances between galaxies and galaxy clusters.

Types of Cepheids

There are different “flavors” of Cepheids. The “classical” ones have pulsation periods ranging from a few days to a few months. They’re all more massive than the Sun and can be up to a hundred thousand times more luminous. Their radii can change pretty drastically during a cycle—some grow by millions of kilometers and then shrink. Type II Cepheids have pulsation periods between 1 and 50 days and are usually very old, low-mass stars. There are other types, including anomalous Cepheids with very short periods. Scientists also know about double-mode Cepheids with “heartbeats” that pulsate in two or more modes.

Some pretty well-known stars are Cepheid variables. For example, Polaris—the well-known “North Star” is one, as is RR Puppis, Delta Cephei, and Eta Aquilae—all visible from Earth. Why these stars pulsate is still being studied but here’s a very basic look at their process. The core of the star produces heat which heats the outer layers. They expand, and then cool. Radiation is escaping, which makes the star appear brighter. The cooler gas contracts under gravity and makes the star look smaller and cooler. Of course, the devil is in the details, which is why astronomers want to know more about the processes these stars undergo.

Polaris A (Pole Star) with its two stellar companions, Polaris Ab and Polaris B. Polaris itself is a Cepheid type variable star. Artists impression. Credit: NASA

However, it turns out Cepheids are not exactly easy to study. For one thing, it’s tough to measure their pulsations and radial velocities accurately. In addition, some have companion stars and the presence of a nearby star complicates any measurements. For another thing, different instruments and measuring methods give slightly different results, which doesn’t help astronomers understand those stars any better.

Precision Measurements of Cepheid Variables

Measuring the intricacies of Cepheid pulsations requires spectroscopic techniques that can measure light from stars and break it down into its component wavelengths. That reveals a lot of data about a star, including its chemical makeup, temperature, and motions in space.

Calibrated Period-luminosity Relationship for Cepheid variables. Courtesy Spitzer Space Telescope/IPAC.

A worldwide consortium of astronomers led by Richard I. Anderson at Switzerland’s École Polytechnique Fédérale de Lausanne (EPFL) is measuring specific properties of classical and other Cepheids using two high-resolution spectrographs. One is called HERMES on La Palma in the northern hemisphere and the other is CORALIE in Chile. They both detected tiny shifts in the light of target Cepheids. Those shifts gave valuable information about the motions of the stars.

“Tracing Cepheid pulsations with high-definition velocimetry gives us insights into the structure of these stars and how they evolve,” he said. “In particular, measurements of the speed at which the stars expand and contract along the line of sight—so-called radial velocities—provide a crucial counterpart to precise brightness measurements from space. However, there has been an urgent need for high-quality radial velocities because they are expensive to collect and because few instruments are capable of collecting them.”

VELOCE is on the Job

The team’s measurement project is called the VELOCE Project—short for VELOcities of CEpheids. It’s 12-year-long collaboration among astronomers and astrophysicists. Anderson began the VELOCE project during his Ph.D work at the University of Geneva, continued it as a postdoc in the US and Germany, and has now completed it at EPFL.

According to Ph.D student Giordano Viviani, the data from the project are already enabling new discoveries about Cepheids. “The wonderful precision and long-term stability of the measurements have enabled interesting new insights into how Cepheids pulsate,” Viviani said. “The pulsations lead to changes in the line-of-sight velocity of up to 70 km/s, or about 250,000 km/h. We have measured these variations with a typical precision of 130 km/h (37 m/s), and in some cases as good as 7 km/h (2 m/s), which is roughly the speed of a fast walking human.”

Uncovering New Details about these Pulsating Stars

The VELOCE project’s precision measurements also revealed some strange facts about these stars. For example, there’s an interesting phenomenon called the Hertzsprung Progression. It describes double-peaked bumps in a Cepheid’s pulsations. Astronomers aren’t quite sure yet why these bumps occur. But, they could give some insight into the structure of Cepheid variables, particularly the so-called “classical” ones.

Other Cepheids show very complex variability, and changes in their radial velocities are not always consistent with predicted periods, according to postdoctoral researcher Henryka Netzel. “This suggests that there are more intricate processes occurring within these stars, such as interactions between different layers of the star, or additional (non-radial) pulsation signals that may present an opportunity to determine the structure of Cepheid stars by asteroseismology,” Netzel said.

As part of their study, the team also measured 77 Cepheids that are part of binary systems. One in three Cepheids “lives” in a binary system, and often those unseen companions are detectable by velocity measurements. Characterizing the different “flavors” of Cepheids and the intricacies of their pulsations has larger implications than determining their radial velocities and bumps in their periods, according to Anderson. “Understanding the nature and physics of Cepheids is important because they tell us about how stars evolve in general, and because we rely on them for determining distances and the expansion rate of the Universe,” Anderson said, noting that VELOCE is also providing a valuable “cross-check” with Gaia measurements. It’s on track to conduct a large-scale survey of Cepheid radial velocity measurements.

Cross-checking with Gaia

Additionally, VELOCE provides the best available cross-checks for similar, but less precise, measurements from the ESA mission Gaia. That spacecraft is on track to conduct the largest survey of Cepheid radial velocity measurements. Data from that mission provides a growing three-dimensional map of millions of stars in the Milky Way and beyond. It not only charts their positions but also their motions (including radial velocity), as well as temperatures and compositions. Combined with high-precision data from VELOCE about Cepheids, astronomers should soon be able to get a handle on stellar and galactic evolutionary history.

For More Information

High-precision Measurements Challenge the Understanding of Cepheids
VELOcities of CEpheids (VELOCE)

The post Cepheid Variables are the Bedrock of the Cosmic Distance Ladder. Astronomers are Trying to Understand them Better appeared first on Universe Today.

Hubble's NGC 1546