Local Bubbles | 14 Jan 2023

Why in News?

Recently, new research on a giant cosmic cavity that surrounds the solar system could reveal the universe’s secrets, including questions about the origins of stars.

• Researchers from the Center for Astrophysics (CfA) | Harvard & Smithsonian have generated a 3D magnetic map of the cavity called Local Bubble.

What are Local Bubbles?

• The Local Bubble is a 1,000-light-year-wide cavity or a superbubble. Other superbubbles also exist in the Milky Way.
• The Local Bubble is a large, low-density region in the interstellar medium (ISM) of our galaxy, the Milky Way.
  • The interstellar medium is the material which fills the space between the stars.
• It's a cavity that is thought to have been created by a series of supernovae explosions that occurred about 30 to 50 million years ago.

What is a Supernova?

• A supernova is a powerful and luminous explosion that occurs at the end of the life of a massive star.
• It is caused by the collapse of the core of the star, which can trigger a massive release of energy.
• Supernovae are also important for the enrichment of the interstellar medium with heavy elements and for the propagation of cosmic rays.
• There are two main types of supernovae:
  • Type I:
    • It is a supernova caused by the thermonuclear explosion of a white dwarf star that is part of a binary system.
    • The white dwarf accretes material from its companion star, and when its mass exceeds a certain limit, it becomes unstable and detonates.
  • Type II:
    • It is caused by the gravitational collapse of the core of a massive star.
    • When a star has exhausted the nuclear fuel in its core, its outer layers collapse inward, and the core becomes incredibly hot and dense.
    • This causes a huge release of energy, which causes the star to explode.
    • The explosion is so powerful that it can outshine an entire galaxy for a brief period of time, and the explosion debris can cause the formation of nebulae, dust and heavy elements.

How 3D Map of a Gigantic Cavity of Local Bubbles Observed?

• They used Gaia and Planck space based observatories launched by the European Space Agency (ESA).
• Gaia was used to identify the location and local concentration of cosmic dust.
  • This helped them trace the boundaries of the Local Bubble.
• Planck provided information on the magnetic alignment of cosmic dust.
• This alignment can indicate the orientation of the magnetic field acting on the dust particles, allowing the researchers to generate a 3D magnetic field orientation on the surface of the Local Bubble.

Source: DTE