Sirius ($SIRS) is a token that lets you automatically participate in Liquidity Baking, a decentralized liquidity pool between tez and tzBTC that is incentivized at the protocol level on the Tezos blockchain. Before Sirius, users needed to conduct a multi-step transaction to deposit tez and tzBTC into the liquidity baking pool. Now, earning liquidity baking rewards is as simple as purchasing Sirius ($SIRS).