HD 148937 Binary Star and Nebulae NGC 6164 and NGC 6165: Latest Discoveries by ESO Astronomers

This is the binary star “HD 148937” about 3,800 light-years away towards the constellation “Polymera” in the southern sky, and the nebulae “NGC 6164” and “NGC 6165” which spreading around. The bright central star is HD 148937, the upper right (northwest side) is called NGC 6164, and the lower left (southeast side) is called NGC 6165.

[▲Rionnagbinary”HD148937″agusnebulae”NGC6164″agus”NGC6165″airathogaille”VLTSurveyTelescope(VST)”aigParanalObservatory(Creideas:sgiobaESO/VPHAS+.Aithneachadh:CASU)]

It is generally believed that several stars in a binary star are formed at the same time, so they must be of the same age. However, a research team led by astronomer Abigail Frost from the European Southern Observatory (ESO) discovered the two massive stars that make up HD 148937, the companion star is estimated to be around 2.7 million years old about 1.4 million years old, and in some cases about 3.9 million years old (depending on how the age of the companion star is estimated).

Another difference is that while the host star has a magnetic field, which is unusual for a massive star, the companion star does not. According to ESO, magnetic fields are a common feature of light stars like the Sun, but massive stars cannot maintain magnetic fields like lighter stars can. However, some massive stars have magnetic fields, which is one of the long-standing mysteries of astronomy.

In addition, NGC 6164 and NGC 6165, which surround HD 148937, are several hundreds of years younger than this binary star, forming only about 7,500 years ago. In addition, the nebula is said to be rich in elements such as nitrogen, carbon, and oxygen. Not surprisingly, they are found in objects associated with “stellar death,” such as planetary nebulae and supernova remnants, but these are usually found deep inside the star in a star like HD 148937. that it is supposed to be an element, perhaps it was released by a destructive event that happened in the past.

[▲EachdraidhHD148937marachaidhfhaicinnleisansgiobarannsachaidh.Clìguh-àrd:Dealbhmac-meanmnachdenuairabhaenarionnagtrì-fhillteledàrionnagfaisgairachèileagusaonrionnagfadabhochèile.Deasguh-àrd:Ìomhaighmac-meanmnachdedhàrionnagfaisgairlàimha’tighinncòmhlaagusa’deàrrsadhgudian.Guh-ìosalairantaobhchlì:Beachdneach-ealainairnuairathaansoilleireachdairlagachadhagusnareultanrimfaicinna-rithist.Guh-ìosalairanlàimhdheis:ÌomhaighfìordeHD148937(Creideas:ESO/L.CalçadasgiobaVPHAS+.Aithneachadh:CASU)]

Therefore, Frost and his colleagues analyzed HD 148937 using nine years of observational data obtained by the ESO-operated VLT Interferometer (VLTI) at the Paranal Observatory in Chile. The VLTI is an interferometer that combines the four telescopes with an aperture of 8.2 if that make up the Very Large Telescope (VLT) at the Paranal Observatory. As a result of the analysis, the research team came up with the following scenario.

HD 148937 was originally formed as a triple star consisting of three stars. It is believed that two of the three stars were close to each other and one was orbiting at a distance from each other. Eventually, the two stars that were close to each other merged into one star with a magnetic field, and the material ejected into the surrounding area formed a nebula. This scenario could successfully explain such mysteries as the different ages of the host and companion stars, the unusual magnetic fields of massive stars, and the elemental composition of the nebula.

According to ESO, it is thought that the magnetic field of a massive star could be created by the merger of two stars, and this result is the first direct evidence of this intriguing possibility. . “The magnetic field of a massive star is expected to last only for a short time compared to the age of the star, so we may have seen this rare phenomenon just after it happened,” said Frost. A paper summarizes An account of the research team’s findings is published in Science.

[▲EachdraidhHD148937marachaidhfhaicinnleisansgiobarannsachaidh(bhidio)]
（Credit: ESO/L. Pavement team, M. Kornmesser/VPHAS+. Credit: CASU）

In addition, ESO is progressing the construction of the next generation large telescope, the European Extremely Large Telescope (ELT), in Cerro Almazones, Chile. It is hoped that ELT will allow us to investigate in more detail what happened to HD 148937, which may reveal even more surprises.

Source

• THERE ARE – A beautiful nebula, a violent history: star conflicts solve stellar mysteries
• Frost et al. – A massive magnetic star has experienced a stellar merger (Science, arXiv)

Text Editing/Editorial/sorae Department