PHE-15 IGNOU Solved Assignment 2026-27

PHE-15 Solved Assignment: Astronomy and Astrophysics (TMA-01 & TMA-02)

The following is a structured breakdown of the IGNOU PHE-15 solved assignment solutions, strictly adhering to the official B.Sc. curriculum (School of Sciences). Each block includes verified answers for short-answer, long-answer, and numerical problems with precise referencing to the Study Material and eGyanKosh resources.

1. Block-1: Basics of Astronomy

• Key Topics Covered:
  • Fundamental principles of astronomy (celestial mechanics, coordinate systems)
  • Historical development: Ptolemaic vs. Copernican models
  • Optical telescopes and their resolving power (Rayleigh criterion)
  • Electromagnetic spectrum and astronomical observations
• Solved Assignment Focus:
  • Explain the differences between apparent and absolute magnitudes (500-word limit).
  • Calculate the angular diameter of Jupiter given its actual diameter (100 words).
  • Compare the working principles of refracting and reflecting telescopes (250 words).

2. Block-2: The Solar System and the Stars

• Key Topics Covered:
  • Planetary motion: Kepler’s laws and Newtonian mechanics
  • Classification of stars (Hertzsprung-Russell diagram)
  • Stellar structure: Hydrostatic equilibrium and energy generation (PP chain)
  • Blackbody radiation and Wien’s displacement law
• Solved Assignment Focus:
  • Derive the relationship between luminosity, temperature, and radius using Stefan-Boltzmann law (100 words).
  • Discuss the lifecycle of a star like the Sun (500 words).
  • Explain the significance of the Oort Cloud in the solar system (250 words).

3. Block-3: From Stars to Our Galaxy

• Key Topics Covered:
  • Galactic structure: Milky Way morphology and spiral arms
  • Galactic dynamics: Rotation curves and dark matter evidence
  • Star clusters (open vs. globular) and their observational properties
  • Galactic nucleosynthesis and chemical evolution
• Solved Assignment Focus:
  • Analyze the evidence supporting dark matter in the Milky Way (500 words).
  • Compare the characteristics of open and globular clusters (250 words).
  • Describe the role of supernovae in enriching the interstellar medium (100 words).

4. Block-4: Astronomy and Astrophysics

• Key Topics Covered:
  • Cosmology: Big Bang theory and observational proofs (CMB, Hubble’s law)
  • Active galactic nuclei (AGN) and quasars
  • Gravitational lensing and its applications
  • Exoplanet detection methods (transit photometry, radial velocity)
• Solved Assignment Focus:
  • Explain the role of the Cosmic Microwave Background (CMB) in supporting the Big Bang theory (500 words).
  • Describe the transit method for detecting exoplanets (250 words).
  • Calculate the redshift of a galaxy at a distance of 1 Gpc using Hubble’s law (100 words).

5. Submission Guidelines

• Word limits strictly enforced (500/250/100 words per question).
• Answers include references to IGNOU Study Material (e.g., Chapter 3, Section 3.2).
• Digital PDF includes TMA-01 and TMA-02 solutions with deadline-compliant formatting.

FAQs

• Q: Are the solutions plagiarism-free?

  Yes. All answers are generated using IGNOU-verified references and adhere to academic integrity policies. Cross-referenced with eGyanKosh and Study Material.

• Q: How are numerical problems solved?

  Step-by-step derivations are provided with SI unit consistency and clear assumptions (e.g., Hubble constant = 70 km/s/Mpc).