Astronomers have excavated a galactic tomb –a stunning picture of our home galaxy’s successive mergers with neighboring galaxies. Recent discoveries by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) revealed the “archaeological” record embedded in hundreds of thousands of stars that unveiled the assembly history and evolution of our Milky Way Galaxy.
The first black hole to be discovered was Cygnus X-1 in 1964. It comprises a black hole and a blue supergiant star orbiting each other. The black hole is accreting from the wind of the blue supergiant, forming a hot disk around the black hole that emits powerful X-rays. The mass of the invisible companion is calculated to be 8-10 solar masses, much too large to be a neutron star.
“The planet in b Centauri is an alien world in an environment that is completely different from what we experience here on Earth and in our Solar System,” explains co-author Gayathri Viswanath, a researcher in exoplanet detection at Stockholm University. “It’s a harsh environment, dominated by extreme radiation, where everything is on a gigantic scale: the stars are bigger, the planet is bigger, the distances are bigger.”
The young star Eta Carinae –one of the most massive in the Milky Way – survived a titanic eruption 170 years ago. Although located relatively far away from Earth (about seven thousand light-years away, as compared with the average distance of naked-eye stars of about a thousand light-years), it can be seen easily by people in the southern hemisphere because it is extraordinarily bright—about five million times more luminous than our Sun.
“Seeing this star is really amazing as we know it must have formed in the galactic center, a place very different to our local environment. It is a visitor from a strange land,” said NASA Hubble Fellow Ting Li with the Carnegie Observatories and Princeton University, about the discovery of the ultrafast star, S5-HVS1 in 2019, traveling at a blistering 6 million km/h. The doomed star was slingshotted by the supermassive black hole at the heart of the Milky Way five million years ago at the dawn of the human species.
Stars are born in nurseries with a collection of siblings that range in mass but share chemical compositions and dynamic histories. As time passes, the tightly bound nursery that they were born inside dissipates with increased gravitational interactions from outside sources (passing giant molecular clouds or stars). One form of evolved stellar nurseries is called a “moving group”. In this article I will review four fast facts about these loosely bound collections of co-moving, co-evolving stars.
Jackie Faherty, astrophysicist at the American Museum of Natural History and Editor at The Daily Galaxy.
Editor, Jackie Faherty, astrophysicist, Senior Scientist with AMNH. Jackie was formerly a NASA Hubble Fellow at the Carnegie Institution for Science. Aside from a love of scientific research, she is a passionate educator and can often be found giving public lectures in the Hayden Planetarium. Her research team has won multiple grants from NASA, NSF, and the Heising Simons foundation to support projects focused on characterising planet-like objects. She has also co-founded the popular citizen science project entitled Backyard Worlds: Planet 9 which invites the general public to help scan the solar neighbourhood for previously missed cold worlds. A Google Scholar, Faherty has over 100 peer reviewed articles in astrophysical journals and has been an invited speaker at universities and conferences across the globe. Jackie received the 2020 Vera Rubin Early Career Prize from the American Astronomical Society, an award that recognises scientists who have made an impact in the field of dynamical astronomy and the 2021 Robert H Goddard Award for science accomplishments.