Analyzing datasets of the Palomar Gattini (PGIR) infrared survey and NASA’s NEOWISE spacecraft, astronomers have found a flaring young stellar object (YSO) in the star-forming region of NGC 281-W.
YSOs are stars in the early stages of evolution, in particular protostars and pre-main sequence stars.
Let us recall that a protostar is a star at the initial stage of its evolution and at the final stage of its formation before the onset of thermonuclear fusion. The exact boundaries of this concept are blurred, and the protostars themselves can have completely different characteristics. In turn, stars before the main sequence, unlike protostars, are already visible in the optical range. Thermonuclear reactions can already take place in them, but not enough energy is released in them to compensate for the energy losses due to the radiation of the star.
They are usually found trapped in dense molecular clumps, in a medium containing large amounts of molecular gas and interstellar dust.
Taking into account that episodic accretion processes take place in YSO, as a result, outbreaks are observed in stars in the early stages of evolution. They occur when the mass of a celestial body grows due to the gravitational attraction of matter on it from the surrounding space. Astronomers usually classify such events as EX Lup (also known as EXors) and FU Ori (or FUors). Exors have several amplitude values and last from several months to one or two years; Fuors are more extreme and rare, can have an amplitude of 5 to 6 magnitudes and last from decades to centuries.
However, so far very little is known about the properties of flares in YSO. The number of such events, which can hardly be attributed to one of the two known classes, is growing. Therefore, the detection of new flares and their detailed study is important for a better understanding of their nature.
Since its inception, the brightness of the PGIR 20dci has gradually increased. The near-infrared image also showed the existence of an extended, comet-type nebula of scattered light about 14,000 AU in size.
The study, published in the Preprint Library, confirms that PGIR 20dci is associated with the star-forming region NGC 281-W, located in the spiral arm of the Perseus galaxy about 9,130 light-years from Earth. Study of the line absorption spectrum of PGIR 20dci in the near infrared region provided important information about the nature of this YSO.
Recent near infrared spectroscopy confirms the similarity of PGIR 20dci to FU Ori-type sources. As a result, the object was identified as a real extreme and rare star in the early stages of evolution.
As the scientists noted in their article, further research is needed, especially at high spectral dispersion, to better understand the properties of PGIR 20dci.