In News:

Recent astronomical observations have produced the largest and most detailed image of the central region of the Milky Way, revealing a complex network of filaments of cosmic gas and previously hidden chemical structures. The discovery was made using the Atacama Large Millimeter/submillimeter Array (ALMA), one of the world’s most advanced radio telescope facilities. These observations provide new insights into the chemical composition, gas dynamics, and star-formation processes occurring near the centre of our galaxy.

Atacama Large Millimeter/submillimeter Array (ALMA)

• ALMA is a state-of-the-art radio telescope array designed to study the universe in millimetre and submillimetre wavelengths, which are particularly useful for observing cold gas, dust, and molecular clouds that are often invisible to optical telescopes.

Location and Development

• ALMA is located in the Atacama Desert of northern Chile, one of the driest places on Earth, offering ideal conditions for radio astronomy due to minimal atmospheric moisture.
• The observatory became fully operational in 2013.
• It is a major international collaboration involving:
  • National Radio Astronomy Observatory (NRAO), USA
  • National Astronomical Observatory of Japan (NAOJ)
  • European Southern Observatory (ESO).

Key Features

• 66 high-precision antennas arranged across distances of up to 16 km on the Chajnantor Plateau.
• The antennas can be repositioned, allowing astronomers to adjust resolution similar to a camera’s zoom lens.
• ALMA possesses extremely high sensitivity, enabling detection of very faint radio emissions from distant cosmic objects.
• It functions as an interferometer, combining signals from multiple antennas to produce extremely detailed astronomical images.

Recent Discovery: Mapping the Milky Way’s Central Region

Using ALMA, astronomers recently produced the largest high-resolution image of the Milky Way’s galactic centre at millimetre wavelengths. This region, located about 26,000 light-years from Earth, is dense with gas clouds, dust, and extreme astrophysical activity.

Key Findings

• Network of Gas Filaments
  • The observations revealed a vast network of thin filaments of molecular gas distributed across the central region.
  • These filaments likely play a crucial role in transporting matter and energy across the galaxy’s core.
• Hidden Chemical Structures
  • Scientists identified previously undetected molecules and complex chemical interactions within dense gas clouds.
  • These findings help researchers understand the chemical evolution of galaxies and the origins of complex organic molecules in space.
• Star Formation and Galactic Activity
  • The galactic centre hosts intense star formation and energetic processes, influenced by strong gravitational forces and radiation.
  • Mapping these structures provides clues about how stars form in extreme environments.
• Improved Understanding of Galactic Dynamics
  • Detailed imaging allows astronomers to track gas movements, turbulence, and interactions near the Milky Way’s centre.
  • This may help explain how matter accumulates around the supermassive black hole Sagittarius A* at the core of the galaxy.

Major Contributions of ALMA to Astronomy

Since becoming operational, ALMA has produced several landmark discoveries:

• Early Starburst Galaxies: ALMA detected starburst galaxies that existed earlier in the universe than previously believed, altering our understanding of galaxy formation.
• Protoplanetary Disc Around HL Tauri: It captured high-resolution images of the protoplanetary disc around HL Tauri, a young star about 450 light-years from Earth, revealing rings where planets are likely forming.
• Observation of Einstein Rings: ALMA has helped scientists study Einstein rings, a phenomenon predicted by Einstein’s theory of general relativity where light from a distant galaxy bends around a massive object, forming a ring-like structure due to gravitational lensing.

Scientific Significance

The recent mapping of the Milky Way’s centre highlights the importance of millimetre and submillimetre astronomy in uncovering cosmic phenomena hidden behind dust clouds. Observations from ALMA help scientists:

• Understand the chemical composition of interstellar space.
• Study the processes of star and planet formation.
• Investigate the dynamics of galactic centres and supermassive black holes.
• Explore the evolution of galaxies across cosmic time.

In News:

An international team of astronomers has recently used South Africa’s MeerKAT Radio Telescope to identify a new giant radio galaxy (GRG) within the COSMOS field, as part of the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. The discovery, published on November 11, offers valuable insights into the formation and evolution of radio galaxies and the large-scale structure of the universe.

About the MeerKAT Radio Telescope

• Location: Situated in the Northern Cape province of South Africa, MeerKAT is a world-class radio interferometer operated by the South African Radio Astronomy Observatory (SARAO).
• Origin: Initially conceptualized as the Karoo Array Telescope (KAT) with 20 dishes, its scope was later expanded to 64 dishes, leading to its renaming as “MeerKAT” (meaning “more of KAT”).
• Specifications: Each dish measures 13.5 meters in diameter, spread across a maximum distance of 8 km.
• Technology: Signals received by individual dishes are transmitted to a central processor, allowing them to function collectively as a single, high-resolution telescope.
• Purpose:MeerKAT is a precursor instrument for the Square Kilometre Array (SKA) — the world’s largest and most sensitive radio telescope project, aimed at exploring the origin and evolution of the universe.
• Significance: Currently, MeerKAT is among the most powerful radio interferometers operating at centimetre wavelengths, enabling detailed observations of distant cosmic structures.

About Radio Galaxies

A radio galaxy is a type of galaxy that emits intense radio waves extending far beyond its visible boundaries. These emissions typically arise from jets and lobes of plasma produced by the galaxy’s active galactic nucleus (AGN), which is powered by a supermassive black hole.

The interaction of these jets with surrounding matter generates synchrotron radiation, making such galaxies prominent sources of radio emissions in the cosmos.

The Discovery: MGTC J100022.85+031520.4

Using MeerKAT’s advanced capabilities, astronomers identified a new giant radio galaxy (designated MGTC J100022.85+031520.4) within the COSMOS field.

Key Characteristics:

• Host Galaxy: Elliptical galaxy SDSS J100022.85+031520
• Redshift: Approximately 0.1034
• Size: About 4.2 million light years in projected length — qualifying it as a Giant Radio Galaxy (GRG)
• Mass: Nearly 93 trillion solar masses
• Radio Power:597 ZW/Hz at 1,284 MHz
• Age: Estimated 1 billion years
• Jet Power: Around 1 million QW
• Location: Identified as the Brightest Cluster Galaxy (BCG) within the galaxy cluster WHL J100022.9+031521

This makes it one of the few (around 4%) known GRGs that exist within a cluster environment rather than in isolated regions.

Why is it in the News?

New research has found a "missing piece of the puzzle" of West Antarctic Ice Sheet melt, revealing that the collapse of the ice sheet in the Ross Sea region can be prevented—if we keep to a low-emissions pathway.

About Ross Ice Shelf:

• The Ross Ice Shelf is a floating mass of land-ice, with a front between 15 and 50 meters high. ?
• It is the largest ice shelf in Antarctica.
• Situated in the Ross Sea, it extends off the coast into the ocean, covering an impressive 487,000 square kilometers, roughly the size of France.
• Despite its vast surface area, only 10% of the ice shelf is visible above the water, mostly concealed beneath hundreds of meters of ice.
• The thickness of the Ross Ice Shelf varies significantly, ranging from about 100 meters to several hundred meters at its thickest points near the areas where the shelf connects to the Antarctic continent.
• The formation of the Ross Ice Shelf is the result of snow accumulation and compaction over time, which ultimately transforms into ice.
• It is continuously fed by glaciers draining from both the East and West Antarctic Ice Sheets, creating a balance as new ice is added while existing ice is removed through melting at the base and calving at the front.
• This massive ice shelf plays a critical role in stabilizing the Antarctic ice sheet.

About the Ross Sea:

• Location and Size: The Ross Sea is a vast, remote bay located just 320 km from the South Pole, positioned south and slightly east of New Zealand.
• It covers an area of approximately 370,000 square miles (960,000 square km), making it the largest polar marine ecosystem in the world.
• The sea's dynamics are significantly shaped by the coastal East-Wind Drift, which establishes a vast clockwise gyre, complemented by deepwater upwelling phenomena.
• Notably, it holds the distinction of being Antarctica's first protected area, serving as a habitat for a plethora of penguin species and numerous whale species.
• Depth: Despite its vast size, the Ross Sea is relatively shallow, with an average depth of approximately 530 meters.
• Historical Exploration: The sea is named after British explorer Sir James Clark Ross, who first visited the area in 1841 during his expedition to Antarctica.
• The Ross Sea's importance to both the scientific community and global conservation efforts cannot be overstated, as it provides valuable insights into the effects of climate change on polar ecosystems.