THEORY EXAMINATION (SEM–IV) 2016-17 SPACE SCIENCE

Course: B.Tech (All Branches – Common Elective)
Subject Code: EOE044
Subject Title: Space Science
Exam Type: Theory
Duration: 3 Hours
Maximum Marks: 100

SECTION – A (10 × 2 = 20 Marks)

Conceptual short-answer questions focusing on astronomy fundamentals

SECTION – B (5 × 10 = 50 Marks)

Descriptive and theoretical analysis questions

(a) Harvard Classification System

Based on spectral characteristics and surface temperature.

Spectral types: O, B, A, F, G, K, M (hottest to coolest).

Example:

(b) Supernova

Definition: Catastrophic explosion marking the end of a massive star’s life.

Types:

Type I: No hydrogen lines (white dwarf collapse).

Type II: Hydrogen present (massive star collapse).

Produces neutron stars, black holes, and heavy elements.

(c) Quasars vs Microquasars

(d) Big Bang Theory – Early Universe

Planck Era (10⁻⁴³ s) – All forces unified.

Inflationary Epoch – Rapid expansion.

Nucleosynthesis – Formation of light elements.

Recombination Era – Atoms formed; cosmic microwave background (CMB) released.

Galaxy Formation – Matter condensed into stars and galaxies.

(e) Nebular Theory of Solar System Formation

Proposed by Kant and Laplace.

A rotating cloud of gas and dust collapsed under gravity → flattened disk → Sun formed at center → planets formed from accretion.

(f) Hertzsprung–Russell (H–R) Diagram

Plots luminosity (Y-axis) vs temperature (X-axis).

Main Sequence: Stable hydrogen-burning stars.

Red Giants / Supergiants: High luminosity, low temperature.

White Dwarfs: Low luminosity, high temperature.

(g) Kepler’s Law – Analytical Proofs

F=GMmr2F = \frac{GMm}{r^2}F=r2GMm​ (gravitational force).

Using angular momentum conservation:

1. r2dθdt=h=constantr^2 \frac{dθ}{dt} = h = \text{constant}r2dtdθ​=h=constant

→ Derives equal-area law.

For third law:

1. T2=4π2GMr3T^2 = \frac{4π^2}{GM}r^3T2=GM4π2​r3

(h) Life Cycle of the Sun

Nebular Stage → Protostar → Main Sequence (Current)

Red Giant Phase → Planetary Nebula → White Dwarf

Solar Winds: Streams of charged particles (mainly protons & electrons) ejected from corona.

SECTION – C (2 × 15 = 30 Marks)

In-depth and analytical long-answer questions

Q3. Galaxy and Active Galaxy

Normal Galaxy: Collection of billions of stars, dust, and gas bound by gravity (e.g., Milky Way).

Active Galaxy: Core emits enormous energy beyond normal starlight due to accretion of matter into a supermassive black hole.

Types: Seyfert galaxies, Quasars, Radio galaxies, BL Lac objects.

Features: Jets, radio lobes, X-ray/gamma-ray emissions.

Q4. Bode’s Law

Empirical Formula:

• a=0.4+0.3×2na = 0.4 + 0.3 \times 2^na=0.4+0.3×2n

where aaa = planet’s distance (in AU), n=−∞,0,1,2,…n = -\infty, 0, 1, 2, …n=−∞,0,1,2,…

Predicts approximate spacing of planets in Solar System.

Valid for most planets except Neptune and Pluto.

Q5. Unification in Active Galaxies

Unification Theory explains different observed classes (Quasars, Seyferts, Radio galaxies) as same phenomenon viewed from different angles.

Key Patterns:

Orientation Model: Viewing angle affects visibility of jets or core.

Evolution Model: Active galaxies evolve from radio-loud quasars to radio-quiet Seyferts.

Energy Source: Accretion disk + relativistic jets around central black hole.

Summary

This Space Science (EOE044) paper comprehensively tests: