Tidal Tail

Context: A new ultra-diffuse galaxy forming at the end of a tidal tail associated with the galaxy NGC 3785 has been identified recently.

• Discovery: A team of researchers from the National Centre for Radio Astrophysics (NCRA) Pune and Indian Institute of Astrophysics (IIA) conducted a detailed photometric analysis of the Tidal Tail of the NGC 3785 Galaxy.
  • NGC 3785 Galaxy: The Galaxy is about 430 million light years from Earth situated in the Leo constellation.
• Published in: The study was published in the European journal, Astronomy & Astrophysics Letters
• The Formation of an Ultra-Diffuse Galaxy: At the end of the tidal tail of NGC 3785, astronomers have observed the formation of a nascent ultra-diffuse galaxy (UDG). 
  • Ultra -Diffuse Galaxy: These are characterized by their low luminosity and surface brightness, often eluding detection in traditional surveys.
  • Formation of these galaxies are driven by the gravitational interaction between NGC 3785 and a neighboring galaxy.
• Significance: 
  • Understanding Galaxy Evolution: It will open up new avenues for understanding how galaxies evolve and interact in the vast universe.
  • Finding new Cosmic Structures: This research highlights the processes involved in galaxy interactions and the creation of new structures in the cosmos.

About Tidal Tail

• A tidal tail is a long, thin stream of stars and interstellar gas that forms when two galaxies interact closely pulling material away from each galaxy.
• Formation: The gravitational interactions between galaxies can occur during close encounters or mergers, where the gas and stars are often stripped from the outer regions of the galaxies to form two tidal tails,
  • One  trailing and one preceding each galaxy.
• Longest Tidal Tail: The tidal tail of Galaxy NGC 3785 extends for an astonishing 1.27 million light-years, making it the longest ever discovered.

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Henley Passport Index 2025

Context: Singapore has reclaimed its place at the top of the world’s most powerful passports which enjoy visa-free access to 195 out of 227 destinations worldwide, according to the Henley Passport Index.

India’s Ranking

• 2025 Rank: 85th. 
  • Visa-free access to 57 nations.
• Recent Trends: Recovery from 90th (2021) to 80th (2024) but dropped to 85th (2025).

Henley Passport Index 2024

• Original, authoritative ranking of world passports based on destinations accessible without a prior visa.
• Initiated in 2006 as the Henley & Partners Visa Restrictions Index (HVRI).
• Utilizes data from the International Air Transport Association (IATA) and Henley & Partners’ research team.
• Data and Coverage: Index includes 199 passports and 227 travel destinations.
  • Passport’s visa-free ‘score’ is determined by the number of countries it provides access to without a visa.
• Index Authority: Considered the standard reference tool for global citizens and sovereign states in assessing passport rankings and global mobility.

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