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Constraining the properties of neutron star matter – Tech Explorist

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Sometimes neutron stars collide with each other, producing most of the heavy elements, such as silver and gold. Therefore, neutron stars and their collisions are considered unique laboratories to study the properties of matter at densities far beyond the densities inside atomic nuclei.

Heavy-ion collision experiments conducted with particle accelerators are a complementary way to produce and probe matter at high densities and under extreme conditions.

Recent progress in multi-messenger astronomy allowed the international research team, involving scientists from Germany, the Netherlands, the US, and Sweden, to gain new insights into the fundamental interactions in nuclear matter. By combining data from heavy-ion experiments, gravitational-wave measurements, and other astronomical observations, scientists constrain nuclear matter’s properties found in the interior of neutron stars.

Sabrina Huth, Institute for Nuclear Physics at Technical University Darmstadt, said“Combining knowledge from nuclear theory, nuclear experiment, and astrophysical observations is essential to shedding light on the properties of neutron-rich matter over the entire density range probed in neutron stars. We find that constraints from collisions of gold ions with particle accelerators show a remarkable consistency with astrophysical observations even though they are obtained with completely different methods.”

In this study, scientists included information obtained in heavy-ion collisions into a framework combining astronomical observations of electromagnetic signals, measurements of gravitational waves, and high-performance astrophysics computations with theoretical nuclear physics calculations.

The authors used data from gold-ion collision experiments at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, as well as Brookhaven National Laboratory and Lawrence Berkeley National Laboratory in the United States, in their multi-step procedure that analyses constraints from nuclear theory and astrophysical observations, such as neutron star mass measurements from radio observations and information from the Neutron Star Interior Composition.

Additional limitations in the density area where nuclear theory and astrophysical observations are less sensitive have been enabled by including data from heavy-ion collisions in the analysis. This has aided in developing a more comprehensive knowledge of the dense matter. Improved constraints from heavy-ion collisions should help bridge the gap between nuclear theory and astrophysical observations in the future by giving complementary data.

Experiments that investigate higher densities while lowering experimental uncertainties, in particular, offer a lot of promise for providing new constraints on neutron star features. In the next years, new knowledge from either side can be incorporated into the framework to increase our understanding of dense matter.

Journal Reference:

  1. Huth, S., Pang, P.T.H., Tews, I. et al. Constraining neutron-star matter with microscopic and macroscopic collisions. Nature 606, 276–280 (2022). DOI: 10.1038/s41586-022-04750-w

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NASA: Contact lost with spacecraft on way to test moon orbit – Hamilton Spectator

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WASHINGTON (AP) — NASA said Tuesday it has lost contact with a $32.7 million spacecraft headed to the moon to test out a lopsided lunar orbit, but agency engineers are hopeful they can fix the problem.

After one successful communication and a second partial one on Monday, the space agency said it could no longer communicate with the spacecraft called Capstone. Engineers are trying to find the cause of the communications drop-off and are optimistic they can fix it, NASA spokesperson Sarah Frazier said Tuesday.

The spacecraft, which launched from New Zealand on June 28, had spent nearly a week in Earth orbit and had been successfully kick-started on its way to the moon, when contact was lost, Frazier said.

The 55-pound satellite is the size of a microwave oven and will be the first spacecraft to try out this oval orbit, which is where NASA wants to stage its Gateway outpost. Gateway would serve as a staging point for astronauts before they descend to the lunar surface.

The orbit balances the gravities of Earth and the moon and so requires little maneuvering and therefore fuel and allows the satellite — or a space station — to stay in constant contact with Earth.

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My Thesis in 400 Words: Anne Boucher | Institute for Research on Exoplanets – News | Institute for Research on Exoplanets

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Anne Boucher, an iREx student at the Université de Montréal, submitted her doctoral thesis at the end of 2021. She summarises the research project she carried out as part of her Ph.D here.

During my Ph.D, I became interested in the atmosphere of gas giant exoplanets that orbit very close to their star. Thanks to a technique called transmission spectroscopy, I studied the chemical composition of their atmosphere, which gives a lot of information on their formation and evolution mechanisms. The detailed study of these exoplanets, which we sometimes call hot Jupiters or hot sub-Saturns, provides a better understanding of the physical, chemical, and dynamical processes that govern the atmosphere of these celestial objects.

I mainly used data from the SPIRou instrument, a high-resolution spectropolarimeter that operates in the near infrared and is installed at the Canada-France-Hawaii Telescope. We first observed HD 189733 b, one of the most studied exoplanets, to build the analysis codes. By exploiting transit spectroscopy, we were able to confirm the presence of water and determine its abundance. The results obtained, consistent with previous studies, indicate that the atmosphere of HD 189733 b is relatively clear (free of clouds) and that the planet likely formed far from its star, where it is cold enough to find water in the form of ice. A strong blueshift of water absorption was observed, which could be a consequence of the presence of strong winds in the atmosphere.

Artistic representation of the exoplanet HD 189733 b, credit :  NASA, ESA, and G. Bacon (STScI)

Next, we studied WASP-127 b, a less massive exoplanet, but much larger than Saturn. A recent study of data from the Hubble Space Telescope (HST) and the Spitzer Space Telescope could not differentiate between two atmospheric scenarios: a low carbon-to-oxygen (C/O) ratio with little carbon monoxide (CO), or a high ratio with a lot of CO. As this ratio helps to determine how a planet was formed, we decided to use SPIRou, which makes it possible to observe a band of CO not observable with HST and Spitzer. We were able to determine that there was very little CO and a very low C/O, which has rarely been observed, but which is supported by some more realistic training scenarios that vary over time. The SPIRou data also confirmed the presence of water and suggests that, if confirmed, there could even be hydroxyl (OH): an unexpected detection since the exoplanet is so cold.

This work has allowed to develop the expertise of the Université de Montréal in high resolution near-infrared transit spectroscopy, in particular with SPIRou, allowing to explore the atmospheric conditions of hot Jupiters and sub-Saturns. This first joint analysis made on high and low resolution transmission data allowed to obtain better constraints on the atmospheric parameters. This method is proving to be a very powerful tool for the study of atmospheres and will be even more so with the revolutionary capabilities of JWST.

More information

Anne worked on her Ph.D. at the Université de Montréal between 2016 and 2022, under the supervision of David Lafrenière. Her thesis will soon be available.

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Nicolas Cowan, Finalist for the 2021 Relève scientifique Prize – News | Institute for Research on Exoplanets

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Nicholas Cowan. Credit: McGill University.

Nicolas Cowan, Professor at McGill University and a member of both iREx and the McGill Space Institute, is one of the finalists for the Relève Scientifique du Québec 2021 Prize, an award which aims to highlight the commitment and excellence in research of a person 40 years of age or younger.

Nick has been a Professor in the Departments of Physics and Earth and Planetary Sciences at McGill University since 2015. He specialises in astrobiology and mainly studies the surface and atmosphere of exoplanets. He is particularly interested in the climate of these planets found outside of our Solar System.

The researcher mainly uses space- and ground-based telescopes to collect and analyse data which he uses to study the characteristics of various exoplanets. More specifically, the data seeks to measure the reflection of clouds, detect the presence of greenhouse gases via the infrared signature of the atmosphere, and heat transport, i.e. the winds. These data are used to create maps of the surface and the temperature of exoplanets, a method commonly referred to as exo-cartography. The study of the exoplanets’ climate also allows us to learn a lot about that of our planet, Earth.

Nick’s commitment to the research community is illustrated in particular by his participation in numerous NASA and Canadian Space Agency committees to promote the study of planetary climates and to contribute to the planning of future space missions to study exoplanets.

In addition to his work as a researcher, Nick is also involved in the Astronomy in Indigenous Communities program, which aims to attract Indigenous youth to pursue a career in STEM.

It is with pride that the iREx congratulates Nicolas Cowan for this distinction.

About the Relève scientifique du Québec Prize

The Relève scientifique du Québec prize is awarded to a person aged 40 or under who has distinguished themselves by the excellence of their research and who demonstrates the ability to establish and maintain constructive and lasting links with the research community. All disciplines are recognised for this award. Each year one recipient and two finalists are selected.

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