Press Releases - Astronomers Discover First Step Toward Planet Formation - ALMA
The universe described by the Bronze Age story in the Bible is almost laughable in its naivety, yet there are still ignorant people who think it was accurately described by the creator of it.
It has a flat Earth at the centre, with a dome over it to keep the water above the sky out, and the sun and moon are lamps hung from the dome to tell us when it’s day or night. All the stars, which we now know are vast galaxies or even superclusters of galaxies, millions of lightyears away, are described as small lights fixed to the inside of the dome, which can shake lose and fall to Earth during earthquakes.
Apart from a magic man speaking some magic words, there is no explanation of how the planet Earth formed, nor any appreciation of planetary systems orbiting a central sun, and of course, no hint that there could be trillions of such planetary systems or the vastness of the Universe.
Of course, you can't really blame the authors who wrote that stuff in the fearful infancy of our species. They were only doing their best with what little knowledge they had. What you can blame though are the ignorant fools who have failed to keep up with scientific discoveries and who still believe those laughably naïve myths are real science and history.
To add to their embarrassment, astronomers have now confirmed what we have suspected for many years now - that planetary systems and planets like Earth form in the accretion discs of second or third generation stars which were formed from condensing clouds of gas and debris produced by exploding earlier stars at the end of their life. These clouds contained not only hydrogen, helium, lithium and lighter elements but also heavier elements produced in the last stages of the earlier sun's demise as it collapsed inwards, forcing the lighter elements in its core to form heavier elements such as iron, calcium, carbon, silicon, oxygen, etc.
As the new sun's gravity pulls these larger elements towards it, angular momentum forces them into a flattened disc orbiting the sun. It was in these discs that the planets condensed around orbitally-stable centres of gravity.
How do accretion discs form around young suns and how do planets coalesce within them? Accretion discs around young stars and the formation of planets within them are fascinating processes that occur during the early stages of stellar and planetary formation. Here's a step-by-step overview of how these processes generally occur:Japanese astronomers have just discovered an example of the early stages of this accretion process. Their discovery is explained in A news release by the Atacama Large Millimeter/submillimeter Array (ALMA):It's important to note that the details of these processes can vary depending on factors like the mass of the protostar, the composition of the protoplanetary disc, and the presence of other nearby stars. Additionally, ongoing research in the field of astrophysics continues to refine our understanding of these complex processes.
- Protostellar Cloud: It all begins in a region of a molecular cloud where there is a concentration of gas and dust. Gravitational forces cause this region to collapse in on itself. Within this collapsing cloud, there may be multiple clumps or cores that will eventually become individual stars.
- Protostar Formation: As the core collapses, it forms a dense, hot center called a protostar. The protostar continues to accrete material from the surrounding cloud through gravitational attraction.
- Accretion Disc Formation: As material falls onto the protostar, it does not fall directly onto the surface but instead forms an accretion disc around the protostar. This disc is a flat, rotating structure consisting of gas and dust particles orbiting the young star. The conservation of angular momentum causes this material to form a disc rather than falling directly onto the star.
- Planetesimal Formation: Within the accretion disc, small particles of dust and ice collide and stick together due to mutual gravitational attraction and electrostatic forces. These aggregates of dust and ice are called planetesimals. Over time, these planetesimals grow larger through further collisions and accretion.
- Planet Formation: As planetesimals continue to collide and grow, they eventually become large enough to exert a significant gravitational pull. At this point, they are called protoplanets. Protostellar material from the surrounding disc may also be accreted onto these protoplanets. The protoplanets continue to grow and eventually become planets.
- Clearing the Disc: As planets form and grow, they clear out their orbits within the accretion disc. Their gravitational influence causes material to be swept up or pushed away from their orbital paths. This process eventually leads to a cleared gap or a relatively empty region in the disc around the young star.
- Final Planet Arrangement: The final arrangement of planets within a planetary system depends on factors such as the availability of material, the location within the disc, and gravitational interactions between planets. The innermost planets are typically rocky, while the outer planets may consist of gas and ice.
In summary, accretion discs around young stars provide the raw material from which planets form through a gradual process of dust and gas accumulation, collision, and coalescence. The formation and evolution of planetary systems are complex and can result in a diverse range of planetary configurations.
The first steps in planet formation can be capturedThe author's paper in The Astrophysical Journal is published open access:
An international research team led by Specially Appointed Assistant Professor Satoshi Ohashi of the National Astronomical Observatory of Japan conducted high-resolution observations and multi-wavelength observations with ALMA of the protoplanetary disk around the relatively young protostar DG Taurus, and discovered the disk's size. We investigated in detail the structure and the size and amount of dust that is the material of planets. As a result, the disk was flat and there were no traces of planets, indicating that it appeared on the eve of planet formation. Furthermore, it was found that the dust was growing larger on the outside, and that the concentration of dust was higher than usual on the inside. We have clarified the first step in how planet formation begins.
Unraveling the mystery of how planets like Earth were created is an important issue in understanding the origin of life. It is believed that planets are formed by gathering interstellar dust and interstellar gas in a protoplanetary disk surrounding a protostar, but it is unclear when, where, and how planet formation begins. The first step is unknown. On the other hand, it is known that when a planet is formed inside a disk, its gravity creates a ring-like pattern on the disk. In fact, ALMA observations have found ring structures in many protoplanetary disks, suggesting the existence of planets. However, in order to investigate the process by which planets are formed, it is important to closely examine disks that are certain to contain no planets yet. However, due to the difficulty of discovering disks without traces of planets and the difficulty of examining such disks in detail, it is still unclear how planet formation begins.
Therefore, an international research group focused on DG Taurus, a relatively young object among protostars, and used ALMA to examine the disk surrounding the protostar in detail. We observed the distribution of radio wave intensity at a wavelength of 1.3 mm emitted by dust within the disk at an extremely high spatial resolution of 0.04 arcsec, and revealed the detailed structure of the disk. The results revealed that the disk around DG Tauri star is flat and lacks the ring-like pattern seen in disks around relatively old protostars. This is because there are no planets yet in the disk of DG Taurus, and it is thought that this image was captured on the eve of planet formation. Furthermore, we observed the disk at different wavelengths (0.87 mm, 1.3 mm, 3.1 mm), and investigated the radio wave intensity and polarization intensity (the extent to which the vibration directions of the radio waves are aligned). Depending on the size and distribution pattern of dust, the ratio of radio wave intensities at different wavelengths and the polarization intensity of radio waves scattered by dust change. Therefore, by comparing observation results with observation simulations with various patterns of dust size and amount distribution and looking for patterns that closely match, we can determine how much interstellar dust, which is the material for planets, is growing. It is possible to estimate the distribution of its size and amount. Therefore, the size of the dust is relatively larger on the outer side of the disk (approximately 40 astronomical units or more; slightly farther than the distance equivalent to Neptune in the solar system) than on the inner side, which means that the process of planet formation is progressing. I understand that. Previous theories of planet formation have believed that planet formation begins from the inside, but this result contradicts that prediction and suggests that planet formation may actually start from the outside. On the other hand, although the size of the dust is small in the inner space, the content of dust relative to gas is about 10 times higher than in normal interstellar space. Furthermore, these dust particles are often deposited on the disk surface, suggesting that this is the stage in which the planet-forming materials are stored. In the future, it is possible that this accumulation of dust will trigger planet formation.
This observation was made possible by ALMA's extremely high spatial resolution of 0.04 arc seconds, as well as the observation of radio waves emitted by the dust that contain polarized light at three wavelengths. This research is the first in the world to reveal the size and amount of dust in a flat disk with no traces of planets. As a result, new aspects of planet formation sites have been revealed that could not be expected from previous theoretical research or observations of disks where traces of planet formation can be seen. Commenting on the significance of this research.Up until now, ALMA has succeeded in capturing a variety of disk structures and revealed the existence of planets. To answer the question "How does planet formation begin?", it is important to observe flat disks with no traces of planet formation. This research has clarified the initial conditions for planet formation. I think this is a very important achievement.
Specially Appointed Assistant Professor Satoshi Ohashi, first author
National Astronomical Observatory of Japan.
This research result was published in the American academic journal The Astrophysical Journal in August 2023 as “Dust Enrichment and Grain Growth in a Smooth Disk around the DG Tau Protostar Revealed by ALMA Triple Bands Frequency Observations” by Satoshi Ohashi et al. Published on the 28th (DOI: 10.3847/1538-4357/ace9b9.)
Characterizing the physical properties of dust grains in a protoplanetary disk is critical to comprehending the planet formation process. Our study presents Atacama Large Millimeter/submillimeter Array (ALMA) high-resolution observations of the young protoplanetary disk around DG Tau at a 1.3 mm dust continuum. The observations, with a spatial resolution of ≈0.″04, or ≈5 au, revealed a geometrically thin and smooth disk without substantial substructures, suggesting that the disk retains the initial conditions of the planet formation. To further analyze the distributions of dust surface density, temperature, and grain size, we conducted a multiband analysis with several dust models, incorporating ALMA archival data of the 0.87 and 3.1 mm dust polarization. The results showed that the Toomre Q parameter is ≲2 at a 20 au radius, assuming a dust-to-gas mass ratio of 0.01. This implies that a higher dust-to-gas mass ratio is necessary to stabilize the disk. The grain sizes depend on the dust models, and for the DSHARP compact dust, they were found to be smaller than ∼400 μm in the inner region (r ≲ 20 au) while exceeding larger than 3 mm in the outer part. Radiative transfer calculations show that the dust scale height is lower than at least one-third of the gas scale height. These distributions of dust enrichment, grain sizes, and weak turbulence strength may have significant implications for the formation of planetesimals through mechanisms such as streaming instability. We also discuss the CO snowline effect and collisional fragmentation in dust coagulation for the origin of the dust size distribution.With our solar system, the inner 4 planets, Mercury, Venus, Earth and Mars are the rocky planets containing most of the heavier elements, while the outer 4 planets, Saturn, Jupiter, Uranus and Neptune are the gas giants, comprised of the lighter elements. In the accretion disc that is the subject of this article, the larger accretions are found in the outer edge of the disc, not, as would be expected of the heavier elements, the inner sections, so there are other factors, so far not understood, that make either this accretion disc, or the one our solar system formed from, atypical. The explanation for that is still outstanding.
Ohashi, Satoshi; Momose, Munetake; Kataoka, Akimasa; Higuchi, Aya E; Tsukagoshi, Takashi; Ueda, Takahiro; Codella, Claudio; Podio, Linda; Hanawa, Tomoyuki; Sakai, Nami; Kobayashi, Hiroshi; Okuzumi, Satoshi; Tanaka, Hidekazu
Dust Enrichment and Grain Growth in a Smooth Disk around the DG Tau Protostar Revealed by ALMA Triple Bands Frequency
The Astrophysical Journal; 945 110. DOI: 10.3847/1538-4357/ace9b9
Copyright: © 2023 The authors.
Published by The American Astronomical Society. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
However, what we have is a description, supported by observation and measurement, which confirms the formation of planets within an accretion disc orbiting a star. The fact that the authors of the Bible were entirely ignorant of this process, is evidence, if any evidence were needed for people outside the creationist cult, that the Bible could not have been written or inspired by the supposed creator god described in it, who would surely have known better. The fact is though that the Bible contains nothing of science that was not believed by primitive Middle Eastern pastoralists of the demon-haunted Bronze and Early Iron Ages.
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