Cepheid Hypothesis By A.C. Banerjee’s (1942)

A.C. Banerjee’s Cepheid Hypothesis, proposed in 1942, is a theory suggesting that our solar system formed from a dramatic stellar encounter. It posits that the Sun was initially a special type of pulsating star known as a Cepheid variable.

Explanation of the Hypothesis

1. The Sun as a Cepheid: Initially, our Sun was not a stable star like it is today, but a Cepheid variable. These are giant, luminous stars that rhythmically expand and contract, causing their brightness to pulsate over a regular period.
2. The Intruder Star: At some point, another star (an “intruder” star) passed very close to our pulsating Sun.
3. Tidal Interaction and Ejection: The immense gravitational pull of this passing star created powerful tidal forces on the Sun. According to Banerjee, the intruder’s gravity synchronised with the Sun’s own pulsations, amplifying them to a critical point. This combined force became so strong that it caused a massive filament of gaseous material to be ripped or ejected from the Sun’s equator.
4. Planet Formation: This ejected filament of hot gas did not fall back into the Sun. Instead, it was captured by the gravitational field of the passing intruder star, which imparted angular momentum to it, setting it into revolution around the Sun. Over time, this filament cooled and condensed to form the planets, moons, and other bodies of the solar system.

Criticisms

Banerjee’s hypothesis is a type of “catastrophic” or “tidal” theory, which attributes the formation of planets to a sudden, violent event involving an external body. However, like other similar tidal theories (such as the Jeans-Jeffreys tidal theory), it has been largely superseded and is not accepted by the modern scientific community.

The main criticisms against this hypothesis include:

• Low Probability: The chance of such a perfectly timed, close encounter between two stars is astronomically low.
• Condensation Problem: It’s difficult to explain how the extremely hot gas ejected from the Sun could cool down and condense into solid planets rather than simply dispersing into space.
• Angular Momentum: While it attempts to explain the planets’ revolution, the model struggles to accurately account for the specific distribution of angular momentum observed in our solar system, where the planets hold over 99% of the total angular momentum.