The James Webb Telescope has come across the most distant and oldest galaxy known to humankind. It has been named HD1 and is sitting at a redshift of 13.3, currently located 33.3 billion light years from the earth, and viewed at a time when the universe was only about 300 million years old. This on its own is fascinating, but there is more to this discovery than meets the eye. HD1 is challenging scientifically accepted theories about the formation of galaxies and the nature of the early universe. You see, HD1 according to older models is too bright and too massive to exist that soon after the Big Bang.
Original models predicted that galaxies of such size and brightness would take around a billion years to form. The Hubble Space Telescope and previous models supported this assumption, yet Hubble still found unusually bright galaxies. This new data is blowing old assumptions out of the water. However, scientists have been tweaking their models to account for this situation and find that the models might indeed hold up. The highly bright galaxies could be explained by active black holes attracting gas before shooting it back out at a much higher brightness than stars alone could produce. Despite this, galaxies are much bigger much earlier than expected, and this new observation is inspiring a race for new data and study into the earliest stages of the universe. JWST HD1
Posted inUniverse|Taggedastro2110, blog4|Comments Off on JWST: The Newest Oldest Galaxy?
Circling a red dwarf star 40 light years away is a system of seven, Earth-like planets. All seven planets are similar enough in size to Earth to hold atmosphere and potentially have volcanic activity. However, only one of those is located within the Goldilocks zone. In other words, TRAPPIST-1e has the potential to have liquid water on its surface. TRAPPIST 1 Planet Could Host Life
The star around which the planets orbit is a red dwarf, nine percent of the size of the Sun. That means this star will exist for 12 trillion years, and is right at the edge of being a brown dwarf, or failed star, and true star. This means that all seven planets have a semi-major axis smaller than that of Mercury. TRAPPIST-1e orbits its star in roughly six days, which means that all planets are extremely close. Computer models show that the three inner planets to 1e are likely Venusian with run-away greenhouse effect evaporating all liquid water. The outer three planets are probably similar to Mars with frozen water. TRAPPIST-1e
These models are very similar to the ones used by scientists to compare Venus, Earth, and Mars and their atmospheric compositions. TRAPPIST-1e is likely to receive enough energy that it would allow oxygen to be split from hydrogen and small enough in mass for the hydrogen to float away. It is 90 percent the Earth’s size and nearly has a nearly identical density. This leads to the likelihood of a high oxygen atmosphere. Indeed, it has no hydrogen in its atmosphere, raising the possibility of an oxygen-rich atmosphere. The James Webb Space Telescope is scheduled to observe the planet, seeking signs of an atmosphere and signatures of life. It is the most promising exoplanet currently under observation for Earth-like conditions. It also importantly allows for further study of planetary formation conditions both in their geological composition and atmospheric composition. Hydrogen Free Atmosphere
Scientists often try to determine the age of various bodies in the solar system. The Earth and moon are around 4.5 billion years old, and the sun is around 4.6 billion years old. But how do scientists know this? And how confident are scientists in these ages? Scientists use radiometric dating to accurately date different bodies in the solar system. Radiometric dating relies on the fact that some atomic elements decay—that is, they split into other elements, they lose a neutron, or a neutron turns into a proton. The half-life of each element is the time is takes for half of the nuclei to decay. Because we know the half-life of such elements, we can measure the amount of decayed material in a given sample to get a reliable idea of the sample’s age.
As a simple example, consider element A which has a half-life of 10 years before it decays into element B. A sample of element A contained 10 grams of the element when it originally formed. Now, however, the sample contains 5 grams of A and 5 grams of B. Using the element’s half-life, we see that the sample is roughly 10 years old because half of its element A decayed to element B. This is a very basic example and in practice, the equation to predict age is more complex with different half-lives and compositions; however, the premise is still the same.
Seen here is a diagram from Geology In which shows the half-of atomic elements commonly used for radiometric dating.
In the vast expanse of space, two brave pioneers are still journeying to the unknown depths of our solar system and beyond: Voyager 1 and Voyager 2. These twin spacecraft, launched by NASA in 1977, have been exploring the outer reaches of our solar system for over four decades, providing scientists with invaluable information about our planetary neighbors.
Diagram of the Voyager spacecraft. Source: Wikipedia
Voyager 1 and Voyager 2 were designed to study the outer planets of our solar system: Jupiter, Saturn, Uranus, and Neptune. But after completing their primary mission in the 1980s, the spacecraft continued their journey into interstellar space, making them the farthest man-made objects in history. They are still traveling to the nearest star from our solar system, Proxima Centauri, and will arrive there in around 100,000 years.
The Voyager spacecraft are equipped with a variety of instruments to collect data about their surroundings, including cameras, spectrometers, and plasma detectors. Among the most famous images captured by the Voyager cameras are the “Pale Blue Dot” image of Earth and the “Family Portrait” of our solar system, which shows the planets as they would appear from the vantage point of the Voyager spacecraft.
Seen from about 6 billion kilometers, Earth appears as a tiny dot within deep space: the blueish-white speck almost halfway up the rightmost band of light. Source: Wikipedia
One of the most remarkable achievements of the Voyager mission is the discovery of several new moons and planetary rings around the outer planets. Voyager 1, for example, discovered the first evidence of volcanic activity on another planet when it observed plumes of gas and dust erupting from the surface of Io, one of Jupiter’s moons. Voyager 2, on the other hand, discovered ten new moons around Uranus and two new rings around Neptune.
The Voyager spacecraft have also provided us with new insights into the magnetic fields and radiation belts of the outer planets. For example, Voyager 1 detected an unexpected “magnetic highway” at the edge of our solar system where charged particles from inside and outside of our solar system interact. Voyager 2 also detected a mysterious “magnetic bubble” around Uranus that has yet to be fully explained.
“Voyager did things no one predicted, found scenes no one expected, and promises to outlive its inventors. Like a great painting or an abiding institution, it has acquired an existence of its own, a destiny beyond the grasp of its handlers.”
– Stephen J. Pyne
Despite their age, the Voyager spacecraft are still sending back data to Earth, providing us with new information about the region of space surrounding our solar system. The data from Voyager 1 and Voyager 2 have also helped scientists to better understand the dynamics of our solar system and its evolution over time.
Geological activity encompasses the ongoing changes on the surface of terrestrial worlds. This activity is derived from a planet’s internal heat, which is largely attributed to three different processes: accretion, differentiation, and radioactive decay. Accretion occurred when planets were merely planetesimals and still gaining mass to become full planets. When other planetesimals collided with the forming planets, the gravitational potential energy that existed was converted into kinetic energy which turned into thermal energy when the collision occurred. After Earth finally formed, differentiation occurred where densest rock sinks and below less dense rock, forming convection patterns in the mantle and core that creates thermal energy. These convection patterns drive tectonic plate movements that are the cause of earthquakes, volcanic eruptions, and mountain formation. Finally, radioactive decay within terrestrial planets occurs due to the isotopes within the planet. During this decay, thermal energy is created from the mass lost.
The sun produces energy via nuclear fusion—that is, it fuses two atoms into one, releasing a tremendous amount of energy in the process. The most common form of fusion in the sun is when hydrogen atoms are fused into helium—giving off energy in the process due to the lost mass. This is the most efficient form of energy production that we know of, as it follows Einstein’s equation of E=MC^2. No chemical reaction, like the burning of coal or natural gas, can produce such energy.
That begs the question: why don’t we utilize nuclear fusion on Earth? The simple answer is that while we have had success replicating nuclear fusion, the requirements for efficient fusion are still unobtainable on Earth. For fusion to take place, we need tremendous pressure and temperature. While such conditions are feasible on Earth and have obtained, the input energy required to start the fusion is still more than we obtain from the fusion itself.
Recently, a supposed breakthrough occurred in fusion generation at Lawrence Livermore Laboratory in California. The scientists claimed to have used 2.05 megajoules of laser energy to start a fusion reaction which generated around 3 megajoules of energy. This made headlines because, for the first time, a lab fusion reaction generated a net energy gain. However, this is misleading. To power the 2.05 megajoules of energy for the laser, the laboratory needed around 300 megajoules of energy from the power grid. This is because lasers are not perfectly efficient. While the news may lead us to believe that this reaction demonstrates fusion in the near future, the reality is that the total energy input was around 100x the output, and therefore the reaction as a whole was inefficient—proving that we are still many years and breakthroughs away from generating efficient fusion reactions on Earth.
Seen here is an image of the fusion generation bay at Lawrence Livermore Laboratory, obtained from The New York Times.
Tycho Brahe, quite a prominent astronomer in the 16th century, is one of the most well known individuals to have sighted a new light filling the night sky. This strange appearance is now known as SN-1572 or more colloquially Tycho’s Supernova, and is revolutionary towards how we view the night sky.
Historically speaking, this change in the night sky was more evidence against the Aristotelian view of the heavens, acting as another stepping stone towards the Scientific revolution. Beyond that however supernovae, ones from white dwarf binaries (Type Ia), are quintessential tools for analyzing the night sky, due to their luminosity. But scientist still sought to improve the precision and accuracy of these measurements.
SN-1572 serves to ensure this by providing a close and still relatively new observed specimen. Through images from Chandra as seen above, a strange amount of clumping occurred within the remnant of the supernova. To find out exactly why this occurred, simulations were made modeling different possible circumstances for this event; the most accurate being that this was a direct byproduct of the explosion.
The above are models made of the nova, and research showed that only in the presence of asymmetrical explosions could the peculiar shape be possible; lining up well with theories of the supernova coming from multiple concurrent explosions.
These theories and models can be the gateway to further understanding supernovae, and by extension many facets of our universe. Type Ia supernovae in particular are used as metrics for measuring distance, using something known as the distance modulus. Having such a powerful reference allows us to see the far off universe and better understand concepts such as universal expansion, and the spreading of heavy elements. All of this potential comes from studying Tycho’s supernova. So it definitely can be said that this spontaneous blip in the night sky has made its mark on human history and knowledge.
Above is an image of the sun given by SOHO, which is an extraordinarily massive object, which due to that possesses a very large gravitational pull, not just on others but also on itself. Everything that has mass possesses this trait, however these bodies are either two light, or are rigidity enough to counteract this force. However the sun and stars as whole are different, on top of being massive, they are composed of plasma, which is susceptible to deformation when interacted with. So how exactly does these stellar objects not fall into themselves? The reason why is because these bodies are in a constant state of hydrostatic equilibrium.
In the prior paragraph the fluidity of stars was a key issue when involving gravitational force, however this property actually allows the formation of pressure gradient. Imagining the sun as shells of plasma, when gravity forces these shells pushed onto each other, the layers exert a force onto each other as well, one upwards and one downward. As the star contracts these layers are further pushed against one another increasing this inertial force until the upward force is equal to gravity. Repeat this process for as many layers the sun has and a stable sphere is made.
A byproduct of this equilibrium is that since plasma is like a gas, pressure possesses a direct relationship to temperature, which also has direct relationship to energy. So the deeper into the sun you go, the greater the temperature and thus the greater the energy, and at high energy the particles in the sun (Hydrogen and Helium), begin to collide with each other forming bonds. This process is known as nuclear fusion, and is the cause of a stars brightness. The proton-proton chain is a fairly common example of fusion, but what if a star were to be really heavy, or low in hydrogen? This leads to two alternative types of fusion, otherwise known as the CNO cycle and Triple Alpha process.
During the proton proton chain, a star slowly depletes its entire supply of hydrogen. With nothing left to burn and keep up the pressure the core collapses onto itself, heating up the upper layers causing them to expand. Overtime this upper layer starts cooling, so only the now helium predominate (By mass) core is able to undergo fusion. The name of this type of fusion is the Triple Alpha process. In this reaction He-4’s collide with each other forming Be-8 and some gamma rays, this intermediate very quickly decays into C-12 and some He-4. This reaction is far less efficient than the p-p chain producing 1/4 of the amount of energy per cycle, which further cools the star to a red color. This is the type of fusion a red giant undergoes.
Now if a star still has an abundance of heated hydrogen ions a new pathway emerges. First, the more massive the star, the greater the total pressure gradient must be; thus the core temperature and energy must be greater. When a particular star is at least 50% heavier than the sun it is now able to fuse C-12 with H-1, which initiates a chain which starts at N-13, and through fusion and decaying goes through Carbon, Nitrogen and Oxygen. As seen below, initially the CNO cycle may not be as efficient as the p-p chain, however the former possesses a 17th power temperature dependence enabling enormous energy production at high temperatures.
Eventually all of these processes end, and without any energy to keep up the gradient, the star collapses onto itself leading to a wide variety of outcomes. Though that will not happen any time soon, and for now our sun and by extension all stars will keep themselves in equilibrium.
Throughout the 1900s, planetary rotation speeds was generally measured in one of two ways: observing the frequency of which fixed features on planets’ surfaces appear, or observing the patterns of the magnetic field, which change periodically when the magnetic field isn’t aligned with the planet’s axis of rotation. For example, both Earth and Jupiter have magnetic fields tilted about 10 degrees from their axes of rotation.
However, neither of these methods work for Saturn. Its atmosphere is constantly moving and no stationary feature can be pinpointed, and interestingly its magnetic field is perfectly aligned with its axis of rotation. Even a slight change in magnetic signal between the Voyager mission in the 1980s and the Cassini mission in 2004 did not given rotational speed information. The rotational speed was eventually able to be estimated through an alternate method. Saturn’s gravity field and its slight flattening due to its rotational speed can be used to estimate that speed. Information from this blog is sourced from this article.
There have been many recent discoveries that suggest life exists beyond Earth. Some of these include new findings on Enceladus (a small moon of Saturn), exoplanets, and even Mars.
An artist’s concept of Trappist-1 f, 1 of 7 known rocky planets that orbits a red dwarf star. Source: NASA
Enceladus
NASA’s Cassini spacecraft collected data that allowed us to simulate the geochemistry of phosphorus in the ocean. This study helped us reach some interesting conclusions regarding Saturn’s moon Enceladus.
Saturn’s moon Enceladus and its composition. Source: Phys.org
As a result of the study, it found that the presence of dissolved phosphorus is inevitable and may reach levels equal to or more than that of Earth’s oceans. This is significant because the presence of phosphorus is essential for DNA, cell membranes, bones, teeth, and other necessary factors to support life.
Exoplanets
Of all known exoplanets, researchers have estimated that about 1/3 of them resemble Super-Earths.
As such, these Super-Earth’s have attributes similar to that of Earth – habitable qualities like geological activity, shallow oceans, thick atmospheres, etc.
In fact, Astronomers have discovered roughly two dozen exoplanets that could actually be more habitable than Earth. Scientists are hoping that the JWST will be able to observe them more closely in order to analyze their atmospheres for possible signs of life.
Mars
Finally, a new model from the SETI Institute states that Mars used to be wet and had a dense atmosphere that could support warm oceans.
Mars today vs Mars in the past. Source: UniverseToday
The study simulated the evolution of Mars’ atmosphere and found that water vapor concentrated in the lower atmosphere condensed as clouds just like on Earth. This, of course, contradicts previous theories that Mars was cold and mostly dry. These findings suggest that Mars may have once supported life.
What does this mean?
As discussed above, recent studies have found that Enceladus’ ocean is more habitable than previously thought, super-Earth exoplanets more habitable than Earth exist in the dozens, and new evidence suggests that Mars used to be wet with warm oceans.
As our understanding of the universe expands, we may be one step closer to answering the age-old question: is there life beyond Earth?
