OCS (Carbonyl Sulfide) can be used to measure how bright each individual protostar is in a binary system.


  • Quantum-mechanical (QM) calculations of the binding-energy (BE) distribution of OCS on ice grains are calculated to know at what temperature OCS sublimates. Binding Energy is the amount of energy needed to pull a molecule (like OCS) off the surface of a dust grain or ice grain.

K dec is(sublimation) rate — how fast OCS leaves the ice

This formula tells researchers at what temperature OCS evaporates off dust grains.


  • In cold protostellar envelopes (10–20 K), OCS molecules stick to icy dust grains. Molecular line observations are measured to map where OCS is in the gas phase around each protostar.


  • Radiative-transfer and dust–gas thermal modelling calculations of the protostellar envelope are done to compute a temperature profile T(r) at given luminosity, and OCS sublimation radius is calculated. The density profile is also calculated.

  • T(r) Dust temperature at distance r from the protostar is calculated as

  • Iv is observed intensity calculated from below equation,

  • Here, Bv is plank function, Tv optical depth of OCS line, it is calculated from density profile given below

  • Researchers found both young stars in binary have very similar luminosities, around 7 times the Sun’s brightness each.


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