Month: February 2021

Binary star systems are everywhere. They make up a large percentage of all known solar systems: as far as we know, about half of all sun-like stars have a binary partner. But we haven’t had the opportunity to study them in detail yet. That’s going to change. Using data from the European Space Agency’s spaceship Gaia, a team of researchers has just compiled a gigantic new catalog of nearby binary star systems, showing that at least 1.3 million of them exist within 3000 light years of the earth.

This detailed overview of our local galactic neighborhood gives researchers a tremendous choice of binary stars to delve into. Previous studies of binary stars such as the Tycho and Hipparcos catalogs (made between 1997 and 2002) only found around 13,000 paired stars. The sample size of the new Gaia survey is 100 times larger, which allows astronomers to create far more accurate models of star system formation.

The bright spherical swarm to the left of the galactic center in this artist’s depiction shows the 3000 light years around the earth that were examined in the new catalog of binary stars. Photo credit: Kareem El-Badry / UC Berkeley and Jackie Faherty / AMNH

Confirming the existence of a binary system is not an easy task. Two stars that appear close to each other in the sky from our point of view can actually be very far apart. They are simply on a similar line of sight.

To find out if the stars are actually close together, astronomers rely on the parallax effect: the apparent movement of a distant object when the viewer’s perspective changes. In other words, astronomers have to observe the distant stars twice from two different positions in Earth’s orbit around the Sun. The positions of the stars in the sky seem to change from one perspective to the second. If the observed stars seem to move together, they are close to each other; If they don’t, they are far apart.

This GIF shows parallax by comparing two images of Proxima Centauri (the star closest to our Sun). The first image was taken from Earth, the second from New Horizons outside Pluto. The comparison shows that Proxima Centauri is much closer to us than the background stars, which do not seem to move with them. Photo credit: NASA / Johns Hopkins Applied Physics Laboratory / Southwest Research Institute / Las Cumbres Observatory / Siding Spring Observatory / Edward Gomez

Parallax is most useful for measuring nearby stars. Beyond about 3000 light years from Earth, the apparent motion is just too small to be measured accurately. Because of this, this new catalog focuses on nearby binary systems rather than distant ones.

The researchers – Kareem El-Badry, Hans-Walter Rix and Tyler M. Heintz – hope that the new data set will offer astronomers a wealth of new research opportunities. The team is particularly interested in studying binary pairs that include white dwarfs (old stars in their final stages of development). White dwarfs no longer produce fusion reactions in their core, which means that they cool slowly and measurably over time. This makes it possible to estimate the age of the white dwarfs, while main sequence stars (middle-aged stars like our sun) have so far been much more difficult.

This is where studying binary systems becomes useful. As the researchers explain, stars in binary pairs usually form simultaneously with their partners. Both stars were “born from the same gas cloud and have orbited each other ever since. So they are essentially the same age, original composition and distance, but generally different masses and occasionally different stages of evolution. “So if you can date one star in the pair (because it is a white dwarf, for example), you will also know the age of the other star by association, even if it is a main (usually non-datable) star.

The new catalog includes 15,982 of these white dwarf and main sequence binaries – a huge sample size, beyond anything previously available, and allowing astronomers to better understand the history, ages, and evolution of nearby Sun-like stars.

The data also holds some surprises. One of the strangest discoveries is that double stars usually have the same mass as their partners.

“This is really strange,” said El-Badry, “because most of them are separated by hundreds or thousands of AU, so they are so far apart that conventional star formation theories should have their masses random.” But the dates tell a different story: they know something about the masses of their companions. “

El-Badry believes that the best explanation for this phenomenon is that the stars formed close to each other and were later tossed apart by the gravitational pull of other stars and objects passing through the system.

More surprises will emerge as astronomers dive into the new catalog. We have only just begun to determine the makeup of our local galactic neighborhood. Binary systems offer new tools for characterizing our environment. Combined with our growing knowledge of star types, gas clouds and exoplanets, binary star systems help us understand our place in the galaxy better than ever.

Learn more:

Artistic rendering of millions of binary stars observed in the vicinity of Earth. Photo credit: UC Berkeley video by Roxanne Makasdjian, based on animation by Jackie Faherty, AMNH, and data from Kareem El-Badry.

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From the NoTrickZone

By P. Gosselin on February 24, 2021

If you look at NASA’s vegetation index data, the news is good: the globe has made 10% greener so far this century.

This is good news because we know that ultimately this means more acreage and more forest. Ironically, what many experts consider to be a major problem (CO2) is one of the main reasons for greening.

Zoe Phin has a post on the subject on their website that really deserves attention.

The global vegetation index will increase by 10% in 20 years

Zoe downloaded all available vegetation data from NASA in 16-day increments from 2000 to 2021. Here is their result:

NASA’s vegetation index has increased from 0.0936 to 0.1029, which is an increase of 9.94%. Diagram by Zoe Phin

“10% global greening in 20 years! We are incredibly lucky! “Zoe comments on the results. “I just wish everyone would feel that way. But you know that not everyone does. To the extent that humans improve global greening, social parasites want to precisely tax and regulate. No good deed goes unpunished. “

Green for 30 years!

This is not unexpected news for cool climate realists. In August 2019, we reported on a German study that shows how the globe has been greening for three decades. On the basis of satellite images, German science reported: “The vegetation on earth has been growing for decades, as satellite data shows.”

Sahara is shrinking and getting greener

Also not so long ago, a study by Venter et al. (2018) that the Sahara had shrunk by 8% over the past three decades. This is profound as the Sahara covers an area of ​​around 9.2 million square kilometers. Eight percent means more than 700,000 square kilometers more area that has turned green – an area that is almost as large as Germany and France combined.

In terms of vegetation, the planet has probably not had such a beautiful life in about 1000 years.

70% CO2-driven

And there’s more good news if you think CO2 as a greenhouse gas is (it isn’t) a problem.

In August last year, NTZ weekly agent Kenneth Richard cited a study by Haverd et al., 2020) and wrote that “about 70% of the earth’s vegetative greening trend after the 1980s was driven by CO2 fertilization” and that this greening will offset 17 years (equivalent) of the earth’s anthropogenic CO2 emissions by 2100.

There are many more studies to support the good news of the green planet – thanks in large part to humanity. It’s not as bad as the crybaby activists and media portray it. Not nearly.

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Beyond Earth, the general scientific consensus is that Mars is the best place to look for evidence of extraterrestrial life. However, it is by no means the only place. Aside from the many extrasolar planets that have been classified as “potentially habitable”, there are many other candidates here in our solar system. This includes the many icy satellites believed to have internal oceans that could harbor life.

Among them is Titan, Saturn’s largest moon, in whose atmosphere and surface all kinds of organic chemistry take place. For some time now, scientists have suspected that studying Titan’s atmosphere could provide important clues about the early stages of the evolution of life on Earth. Thanks to new research by the technology giant IBM, a team of researchers has succeeded in restoring the atmospheric conditions on Titan in a laboratory.

Her research is described in an article entitled “Imaging Titans Organic Haze at the Atomic Scale,” which recently appeared in the February 12 issue of The Astrophysical Journal Letters. The research team was led by Dr. Fabian Schulz and Dr. Julien Maillard and included many colleagues from IBM Research-Zurich, the University of Paris-Saclay, the University of Rouen in Mont-Saint-Aignan and the Fritz Haber Institute of the Max Planck Society.

This artist’s concept of a lake at the north pole of Saturn’s moon Titan shows raised edges and wall-like features as seen by NASA’s Cassini spacecraft around the Winnipeg Lacus of the moon. Photo credit: NASA / JPL-Caltech

Much of what we know about Titan today is thanks to the Cassini spacecraft, which orbited Saturn from 2004 to 2017 and completed its mission by immersing itself in Saturn’s atmosphere. During this time, Cassini took many direct measurements of Titan’s atmosphere and revealed a surprisingly Earth-like environment. Basically, titanium is the only other body in the solar system in which a dense nitrogen atmosphere and organic processes take place.

Particularly interesting is the fact that scientists believe that the Earth’s atmosphere may have been similar about 2.8 billion years ago. This coincides with the Mesoarchic Era, a time when photosynthetic cyanobacteria created the first reef systems and slowly converted Earth’s atmospheric carbon dioxide into oxygen gas (which eventually led to its current balance of nitrogen and oxygen).

While the surface of Titan is believed to contain clues that might improve our understanding of how life came about in our solar system, getting a clear view of this surface has been a problem. The reason for this lies in the titanium atmosphere, which is permeated by a dense photochemical haze that scatters light. As Leo Gross and Nathalie Carrasco (study co-authors) stated in a recent article published on the IBM Research Blog:

“Titan’s haze consists of nanoparticles made up of a large number of large and complex organic molecules that contain carbon, hydrogen and nitrogen. These molecules form in a cascade of chemical reactions when radiation (ultraviolet and cosmic) hits the mixture of methane, nitrogen, and other gases in atmospheres like titans. “

The PAMPRE experiment, which simulates the atmosphere of Titan. Photo credit: Nathalie Carrasco

As a result, there is still much that scientists do not know about the processes that power Titan’s atmosphere, including the exact chemical structure of the large molecules that make up this haze. For decades, astrochemists have conducted laboratory experiments on similar organic molecules known as tholines – a term derived from the Greek word for “muddy” (or “cloudy”).

Tholines refer to a wide variety of organic carbonaceous compounds that form when exposed to solar UV or cosmic rays. These molecules are common in the outer solar system and are typically found in icy bodies where the surface layer contains methane ice that is exposed to radiation. Their presence is indicated by a surface that is reddish in appearance or has sepia-colored spots.

For their study, the team led by Schulz and Maillard conducted an experiment in which they observed Tholine at different stages of education in a laboratory setting. As Gross and Carrasco explained:

“We flooded a stainless steel vessel with a mixture of methane and nitrogen and then triggered chemical reactions by means of an electrical discharge, which mimicked the conditions in the titanium atmosphere. We then analyzed over 100 resulting molecules that make up Titans Tholine in our laboratory in Zurich, and obtained images with a resolution of around a dozen with our self-made low-temperature atomic force microscope. “

NASA’s Cassini spaceship looks at the night side of Saturn’s largest moon and sees sunlight that is scattered through the periphery of Titan’s atmosphere and forms a colored ring. Photo credit: NASA / JPL-Caltech / Space Science Institute

By dissolving molecules of different sizes, the team gained insight into the various stages in which these vapor molecules grow, as well as their chemical composition. Essentially, they observed a key component in Titan’s atmosphere as it formed and accumulated to create Titan’s famous haze effect. Conor A. Nixon, a researcher at NASA’s Goddard Space Flight Center (who was not involved in the study) said:

“This paper shows groundbreaking new work on the use of atomic-scale microscopy to study the structures of complex organic molecules with multiple rings. A typical analysis of laboratory-generated compounds using techniques such as mass spectroscopy shows the relative proportions of the various elements, but not the chemical bond and structure.

“For the first time, we are seeing the molecular architecture of synthetic compounds that are similar to what is believed to be the cause of the orange haze of Titan’s atmosphere. This application now offers an exciting new tool for sample analysis of astrobiological materials, including meteorites and returned samples from planetary bodies. “

In addition, their results could shed light on the mysterious methane-based hydrological cycle of Titan. On earth, this cycle consists of water that changes between a gaseous state (water vapor) and a liquid state (rain and surface water). On Titan, the same cycle takes place with methane, which passes from the atmospheric methane gas and falls as methane rain into the famous hydrocarbon lakes of Titan.

A proposed eight-winged drone (also known as a “dragonfly”) could be ideally suited for exploring Saturn’s moon Titan in the decades to come. Photo credit: APL / Michael Carroll

If so, the research team’s results could reveal the role that chemical haze plays in Titan’s methane cycle, including whether or not these nanoparticles can float on its methane lakes. In addition, these results could reveal whether similar atmospheric aerosols contributed to the creation of life on Earth billions of years ago.

“The molecular structures that we have now shown are known to be good absorbers for ultraviolet light,” describe Gross and Carrasco. “That in turn means that the haze may have acted as a shield protecting DNA molecules on the earth’s early surface from harmful radiation.”

If this theory is correct, the team’s results would not only help scientists understand the conditions under which life arose here on Earth, but they could also point to the possible existence of life on Titan. The mysterious nature of this satellite first became apparent to scientists in the early 1980s when the spacecraft Voyager 1 and 2 both flew through the Saturn system. Since then, scientists have put together

By 2030, NASA plans to send a robotic rotary wing aircraft named Dragonfly to Titan to explore its surface and atmosphere and look for possible signs of life. As always, the theoretical work and laboratory experiments that have been conducted in the meantime will allow scientists to narrow the focus and increase the likelihood that the mission (once it arrives) will find what it is looking for.

Further reading: IBM, The Astrophysical Journal Letters

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