Disturbance in star formation due to a storm
In the lenticular galaxy NGC 1266, astronomers have revealed the existence of a “perfect storm” that is disturbing the star formation in a region that otherwise would be a perfect incubator.
The jets of matter powered by supermassive black holes can consume the fuel needed to give rise to the birth of new stars making galaxies “red and inactive”, i.e. rich and poor old red stars and hydrogen. Today, however, thanks to a series of observations made with ALMA on the distribution of gas and dust in the nucleus of NGC 1266, astronomers have revealed the existence of a “perfect storm” that is disturbing their star formation in a region would otherwise be a perfect incubator.
Credit: NASA/ESA Hubble
NGC 1266 is a lenticular galaxy nearby, located about 100 million light years away in the southern constellation of Eridano containing a black hole relatively modest. Those shaped lenticular galaxies are intermediate between ellipticals and spirals, but they have enough interstellar gas to generate the stars. The turbulence phenomena are caused by the jets emerging from the central black hole in the galaxy and are disturbed by an envelope of gas incredibly dense. This region of high density, which can be the result of a recent merger with another smaller galaxy, blocks almost 98% of the material that is ejected along the jets. “As a kind of strength in continuous action that acts against an immovable object, when the particles that move along the jets interact with the surrounding dense gas, they encounter a resistance that are almost completely blocked,” says Katherine Alatalo the California Institute of Technology and author of the paper published in the Astrophysical Journal. This kind of high energy collision produces a strong turbulence in the gas surrounding disturbing the first critical phase of the process of star formation. “What we are seeing is the most significant reduction of the processes of star formation ever recorded,” says Alatalo.
Past observations of NGC 1266 have allowed revealing a huge flow of gas from the galactic center that is spreading with speeds up to 400 km / sec. The authors estimate that the flow of gas is so powerful that can be compared to the explosion of contemporary 10,000 stars. The jets, despite enough energy to act on the gas, however, are not so powerful as to transmit the speed necessary for him to leave the system. “Put another way, we could say that the jets cause turbulence in the gas to the point that it is no longer able to collapse and then to form new stars,” says Mark Lacy of the National Radio Astronomy Observatory and co-author of the study.
Credit: NASA/ESA Hubble
The gas distributed in the region observed by ALMA (Atacama Large Millimeter / submillimeter Array) has a mass of about 400 million solar masses, an amount 100 times greater than that found in giant molecular clouds in the Milky Way. Usually, such a gas concentration should produce a number of stars at a rate at least 50 times higher than that observed. So far, astronomers have considered that only quasars and radio galaxies may contain supermassive black holes active and powerful enough to act as a sort of “cosmic switch” of the processes of star formation. “Usually it is assumed that the jets are so powerful to expel gas from the galaxy entirely and block accordingly star formation,” says Lacy.
To make this discovery, astronomers have identified initially the position associated emission of radiation in the far infrared, usually correlated with those regions where new stars are forming. In the case of NGC 1266, this radiation comes from a compact region in the center of the galaxy. “The area where it comes from the infrared radiation is very, very small to be attributed to the processes of star formation,” says Alatalo. With high sensitivity and power exploratory ALMA observations, which were supported by CARMA (Combined Array for Research in Millimeter-wave Astronomy), have identified the location of the super dense molecular gas in the galactic center and verify the fact that the gas actually surrounds the compact region where it comes from infrared radiation.