Tuesday, February 22, 2022

  -  3475  -  MILKY WAY  GALAXY  -  new pictures emerging?   An unprecedented new telescope image of the Milky Way galaxy's turbulent center has revealed nearly 1,000 mysterious strands, inexplicably dangling in space.  Stretching up to 150 light years long, the one-dimensional strands (or filaments) are found in pairs and clusters, often stacked equally spaced, side by side like strings on a harp. 


-------------  3475  -  MILKY WAY  GALAXY  -  new pictures emerging?

-  Observations at radio wavelengths discovered the highly organized, magnetic filaments in the early 1980s. The mystifying filaments comprise cosmic ray electrons gyrating the magnetic field at close to the speed of light. But their origin has remained an unsolved mystery ever since.

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-  Now, the 2022 image has exposed 10 times more filaments than previously discovered.  This has allowed statistical studies across a broad population of filaments for the first time. 

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-   Astronomers have studied individual filaments for a long time with a myopic view.  Now they can see a panoramic view filled with an abundance of filaments. Just examining a few filaments makes it difficult to draw any real conclusion about what they are and where they came from. This is a watershed in furthering our understanding of these structures.

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-  To construct the image with unprecedented clarity and detail, astronomers spent three years surveying the sky and analyzing data at the South African Radio Astronomy Observatory (SARAO). Using 200 hours of time on SARAO's MeerKAT telescope, researchers pieced together a mosaic of 20 separate observations of different sections of the sky toward the center of the Milky Way galaxy, 25,000 light years from Earth.

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-  Along with the filaments, the image captures radio emissions from numerous phenomena, including outbursting stars, stellar nurseries and new supernova remnants.

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-   To view the filaments at a finer scale they used a technique to remove the background from the main image in order to isolate the filaments from the surrounding structures. The resulting picture was astounded.

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-  While many mysteries surrounding the filaments remain astronomers have been able to piece together more of the puzzle. They specifically explored the filaments' magnetic fields and the role of cosmic rays in illuminating the magnetic fields.

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-  The variation in radiation emitting from the filaments is very different from that of the newly uncovered supernova remnant, suggesting that the phenomena have different origins. It is more likely that the filaments are related to past activity of the Milky Way's central super massive blackhole rather than coordinated bursts of supernovae. 

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-  The filaments also could be related to enormous, radio-emitting bubbles discovered in 2019.  This is the first time we have been able to study statistical characteristics of the filaments.   We can find the strength of magnetic fields, their lengths, their orientations and the spectrum of radiation.

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-  Among the remaining mysteries is how structured the filaments appear. Filaments within clusters are separated from one another at perfectly equal distances, about the distance from Earth to the Sun.

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-  They almost resemble the regular spacing in solar loops. We still don't know why they come in clusters or understand how they separate, and we don't know how these regular spacing’s happen. Every time we answer one question, multiple other questions arise.  The smarter we get the more we don’t know.

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- We still don't know whether the filaments move or change over time or what is causing the electrons to accelerate at such incredible speeds.  They are currently identifying and cataloging each filament. The angle, curve, magnetic field, spectrum and intensity of each filament. Understanding these properties will give more clues into the filaments' elusive nature.

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-  Best image ever taken of stars buzzing around the Milky Way’s Supermassive blackhole began with the discovery of Sagittarius A*, a persistent radio source located at the Galactic Center of the Milky Way that turned out to be a supermassive blackhole (SMBH). 

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-  This discovery was accompanied by the realization that SMBHs exist at the heart of most galaxies, which account for their energetic nature and the hypervelocity jets extending from their center. Scientists have been trying to get a better look at Sag A* and its surroundings to learn more about the role SMBHs play in the formation and evolution of our galaxy.

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-  This has been the goal of the GRAVITY collaboration, an international team of astronomers and astrophysicists that have been studying the core of the Milky Way for the past thirty years. Using the ESO’s Very Large Telescope Interferometer (VLTI), this team obtained the deepest and sharpest images to date of the region around Sag A*. These observations led to the most precise measurement yet of the blackhole’s mass and revealed a never-before-seen star that orbits close to it.

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-  This unique instrument combines the light of all four 8.2-meter (27 ft) telescopes at the Very Large Telescope’s (VLT) located at the Paranal Observatory in Chile  Astronomers want to learn more about the blackhole at the centre of the Milky Way, Sagittarius A*:

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--------------------  How massive is it exactly?

--------------------  Does it rotate?

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--------------------   Do stars around it behave exactly as we expect from Einstein’s general theory of relativity? 

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-  The best way to answer these questions is to follow stars on orbits close to the supermassive blackhole.

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-  The astronomees have employed a machine-learning technique called “Information Field Theory“. This consisted of modeling how the real light sources would appear, how GRAVITY would observe them, then comparing the simulated results to the actual observations. This allowed them to acquire highly-accurate measurements of Sag A* and images of Galactic Center that were 20 times sharper than any made by the individual VLT telescopes alone.

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-   During their observation period, which ran from March to July, 2021   Precise measurements of the stars that orbit Sag A* were made.  This included “S29“, which holds the record for making the closest and speediest approach around Sag A* ever observed. 

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-  This star made its nearest pass in late May, 2021, passing within 13 billion kilometers (8 billion miles) ,or,  90 times the distance between the Earth and Sun (90 AU) and achieving a velocity of 8,740 km per second (5,430 miles per second). 

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-   Following stars on close orbits around Sagittarius A* allows us to precisely probe the gravitational field around the closest massive blackhole to Earth, to test General Relativity, and to determine the properties of the blackhole.

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-    General Relativity provides a geometric explanation of gravitation and its effect on space-time. Scientists have sought opportunities to test this theory under the most extreme conditions.

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-  These latest observations, combined with the team’s previous data, confirmed that the stars follow paths predicted by General Relativity perfectly. From this, the team was able to constrain the mass of Sag A* to 4,300,000  Solar Masses, the most precise estimate of the blackhole’s mass yet. 

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-   The distance to Sagittarius A* =   27,000 light-years from Earth.

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-  These latest results, which expand on thirty years of observations of our galactic center. 

further and reveal fainter stars that orbit even closer to Sag A*.   The ESO is  busy constructing the Extremely Large Telescope (ELT) in the Atacama Desert in northern Chile. 

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-  Once it is complete, scheduled for 2027, the ELT will be the most powerful observatory in the world and allow for the most precise measurements of these stars’ velocities. It will be joined by the Giant Magellan Telescope (GMT), which is scheduled for completion by 2025.

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-  The more we learn the more we need to know.

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February 20, 2022    MILKY WAY  GALAXY  -  new pictures emerging?      3472                                                                                                                                               

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-----------------------------  Tuesday, February 22, 2022  ---------------------------






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