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A protostar is a very young star that is still gathering mass from its parent molecular cloud. It is the earliest phase in the process of stellar evolution . [ 1 ] For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years. [ 2 ]
The source star is a class I protostar with a total luminosity of 45 L ☉. Two bow shocks separated by 0.44 parsecs make the primary HH 34 system. Several larger and fainter bow shocks were later discovered on either side, making the extent of the system around 3 parsecs.
A star forms by accumulation of material that falls in to a protostar from a circumstellar disk or envelope. Material in the disk is cooler than the surface of the protostar, so it radiates at longer wavelengths of light producing excess infrared emission. As material in the disk is depleted, the infrared excess decreases.
The protostar at first only has about 1% of its final mass. But the envelope of the star continues to grow as infalling material is accreted. After 10,000–100,000 years, [1] thermonuclear fusion begins in its core, then a strong stellar wind is produced which stops the infall of new mass. The protostar is now considered a young star since its ...
NGC 7538, near the more famous Bubble Nebula, is located in the constellation Cepheus.It is located about 9,100 light-years from Earth. It is home to the biggest yet discovered protostar which is about 300 times the size of the Solar System. [4]
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence.Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope of interstellar dust and gas.
HL Tauri (abbreviated HL Tau) is a young T Tauri star [5] in the constellation Taurus, approximately 450 light-years (140 pc) from Earth [1] in the Taurus Molecular Cloud. [6]
The abbreviation is not always a short form of the word used in the clue. For example: "Knight" for N (the symbol used in chess notation) Taking this one stage further, the clue word can hint at the word or words to be abbreviated rather than giving the word itself. For example: "About" for C or CA (for "circa"), or RE.