Stars like our solar finish their lives as white dwarfs. A few of them are surrounded by a planetary nebula consisting of fuel ejected by the dying star shortly earlier than its demise.
A global analysis crew led by Professor Klaus Werner of the Institute of Astronomy and Astrophysics on the College of Tübingen has for the primary time studied a central star of a planetary nebula situated in an open star cluster. The researchers have been in a position to exactly decide the mass that the central star misplaced throughout its lifetime. The outcomes have been revealed within the journal Astronomy & Astrophysics.
There are greater than a thousand open star clusters within the Milky Approach. Every of them includes a set of as much as a number of thousand stars which have fashioned concurrently from a dense cloud of fuel and mud. “The celebrities in a cluster are all the identical age; that has a particular significance for astrophysics,” Klaus Werner reviews. They differ solely in mass. “The extra huge a star is, the quicker it consumes its nuclear gas by fusing hydrogen into helium. So its life is shorter and it evolves right into a white dwarf quicker,” he explains.
Snapshot of celestial improvement
The remark of a star cluster reveals, like a snapshot, the event of stars of various lots on the identical age, Werner says. “In astronomy, star clusters can be utilized as a sort of laboratory the place we are able to measure how dependable our theories of stellar evolution are,” he says. One of many largest uncertainties within the idea of stellar evolution is how a lot matter a star loses throughout its lifetime, he says, including that such mass loss is substantial. “Stars like our solar lose just below half their mass by the point they’ve developed into white dwarfs. Stars with eight occasions the mass of the solar lose about 80 % of their mass,” says the astrophysicist. The connection between the celebrities’ delivery mass and the mass on the time of demise as a white dwarf is understood in astronomy because the initial-final mass relation.
The mass of white dwarfs in star clusters will be immediately associated to the mass that they had at delivery, Werner says. “The information from very younger white dwarfs are significantly precious, as these are the central stars of planetary nebulae,” he explains. Up to now, solely three star clusters are identified to comprise a planetary nebula. “None of their central stars had been studied earlier than as a result of they’re all very distant and faint,” Werner says.
Particular chemical composition
The analysis crew pointed one of many world’s largest telescopes, the ten-meter GRANTECAN telescope on the Canary Island of La Palma, on the central star within the Messier 37 star cluster and analyzed its spectrum. The mass was decided to be 0.85 photo voltaic lots, placing the unique mass at 2.8 photo voltaic lots. “So the star has misplaced 70 % of its matter throughout its lifetime,” Werner explains. One other peculiarity, he says, is its particular chemical composition. The star not had hydrogen on its floor; Werner says this means an uncommon occasion in its current previous – a quick flare-up of nuclear fusion.
Having the ability to make a exact dedication of the initial-final mass relation is of basic significance in astrophysics, says Werner. It determines whether or not a star evolves right into a white dwarf, turns into a neutron star in a supernova explosion, and even whether or not a black gap stays as the ultimate stage. And but, Werner factors out, “new generations of stars are fashioned from the ejected matter, enriched in heavy parts as merchandise of nuclear reactions. That is what the chemical evolution of galaxies – and finally the whole universe – relies upon upon.”