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Science & TechnologyHard

Which structure was identified as the cause of the varying secondary emission lines in Centaurus X-3?

  1. A.The stellar wind of the companion star
  2. B.The surface of the neutron star
  3. C.The accretion stream
  4. D.A ring of dust around the binary

Correct answer

C. The accretion stream

Explanation

The correct answer is the accretion stream, the channel that carries matter from the disk towards the magnetic poles of the pulsar. The team worked out that the structure responsible had to be rotating together with the pulsar, and the stream fits that description: as it swings between the pulsar and the observing satellite, the direct radiation from the pulsar weakens while the light re-emitted by the stream strengthens, producing the variation seen in the emission lines. Option A names the companion's wind, which is one of the structures that scatters radiation in such systems but does not co-rotate with the pulsar in the manner required. Option B names the neutron star's own surface, again a source of secondary radiation but not the changing structure traced here. Option D introduces a dust ring, which does not figure in this study at all. The chain to remember is simple: a stream can only exist if a disk feeds it, so identifying the stream is what established the presence of the disk.

Read the full article: RRI Study Finds Accretion Disk Around Pulsar Centaurus X-3

Practice Questions

Q1.Science & TechnologyMedium

Scientists of which institute found that the X-ray pulsar Centaurus X-3 accretes matter through an accretion disk?

  1. A.Indian Institute of Astrophysics
  2. B.Raman Research Institute
  3. C.Physical Research Laboratory
  4. D.Inter-University Centre for Astronomy and Astrophysics
Show answer
Correct answer: B. Raman Research Institute

The group examined four secondary emission lines from the system and concluded that the structure causing those lines to vary must be turning along with the pulsar, which pointed them to the accretion stream and therefore to a disk feeding it.

Q2.Science & TechnologyHard

Why is the finding about Centaurus X-3 considered unusual?

  1. A.A high-mass X-ray binary usually captures stellar wind directly instead of forming a disk
  2. B.The pulsar was found to have no magnetic field at all
  3. C.The companion star was found to be smaller than the Sun
  4. D.The system was found to lie outside our galaxy
Show answer
Correct answer: A. A high-mass X-ray binary usually captures stellar wind directly instead of forming a disk

In such pairs the companion is a massive star that sheds a strong wind, and the pulsar ordinarily feeds on that wind as it passes, so an orderly disk of matter is not expected.

Q3.Science & TechnologyMedium

At APAC 23, which platform has been created specifically for mobility start-ups?

  1. A.Technology Theatre
  2. B.Exposition
  3. C.TechHive
  4. D.Digital Twin Pavilion
Show answer
Correct answer: C. TechHive

The correct answer is TechHive, described as a dedicated platform created to connect mobility start-ups with the wider automotive ecosystem, where emerging companies can show their innovations and meet industry leaders, technology experts, investors, possible customers and collaborators.

Q5.Science & TechnologyMedium

Where and when will APAC 23 be held?

  1. A.Bharat Mandapam, New Delhi, 13-14 November 2026
  2. B.Yashobhoomi Convention Centre, New Delhi, 13-14 November 2026
  3. C.Pragati Maidan, New Delhi, 3-4 December 2026
  4. D.Chennai Trade Centre, 13-14 November 2026
Show answer
Correct answer: B. Yashobhoomi Convention Centre, New Delhi, 13-14 November 2026

The two-day conference will bring the Asia-Pacific mobility engineering community together at that venue.