Normal Stars & Star Clusters

We are pleased to welcome Nick Wright as our guest blogger. Nick is the lead author on a paper featured in our latest press release, about how magnetic fields are generated in stars. He is an astrophysicist working at Keele University in the UK. He completed his PhD at University College London before moving to the Smithsonian Astrophysical Observatory to study X-ray emission from both young and old stars. After almost 5 years working in the US he returned to England as a Royal Astronomical Society research fellow at the University of Hertfordshire and is now an Ernest Rutherford Fellow at Keele University. When not studying the stars or writing about them on his blog, Nick enjoys cooking, gardening and travelling.

Nick Wright Credit: Nick Wright

Magnetic fields in the Sun and Sun-like stars are generated by a dynamo, a process involving the rotation of the star as well as convection, the rising and falling of hot gas in the star's interior. Understanding the magnetic dynamo of our Sun is important because it is responsible for a lot of interesting and energetic solar phenomena, some of which can have a considerable impact on our Earth and the wider Solar System. The Sun's magnetic field is responsible for sunspots on its surface, the 22-year magnetic activity cycle (the "Solar cycle"), the Solar wind that pummels planets throughout our Solar System and the ejections of large quantities of plasma – a gas composed of free electrons and free atomic nuclei – known as coronal mass ejections. This ejected material can have a serious impact on Earth, resulting in geomagnetic storms that disrupt radio transmissions, damage satellites and electrical grids, as well as harm astronauts or even people flying in airplanes at high altitudes.

Young stars much less massive than the Sun can unleash a torrent of X-ray radiation that can significantly shorten the lifetime of planet-forming disks surrounding these stars. This result comes from a new study of a group of nearby stars using data from NASA's Chandra X-ray Observatory and other telescopes.

Researchers found evidence that intense X-ray radiation produced by some of the young stars in the TW Hya association (TWA), which on average is about 160 light years from Earth, has destroyed disks of dust and gas surrounding them. These disks are where planets form. The stars are only about 8 million years old, compared to the 4.5-billion-year age of the Sun. Astronomers want to learn more about systems this young because they are at a crucial age for the birth and early development of planets.

One of the most recognizable constellations in the sky is Orion, the Hunter. Among Orion's best-known features is the "belt," consisting of three bright stars in a line, each of which can be seen without a telescope.

The westernmost star in Orion's belt is known officially as Delta Orionis. (Since it has been observed for centuries by sky-watchers around the world, it also goes by many other names in various cultures, like "Mintaka".) Modern astronomers know that Delta Orionis is not simply one single star, but rather it is a complex multiple star system.

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young stars that are less than 2 million years old, a blink of an eye in astronomical terms for stars like the Sun expected to burn for billions of years.

The destruction of a planet may sound like the stuff of science fiction, but a team of astronomers has found evidence that this may have happened in an ancient cluster of stars at the edge of the Milky Way galaxy.

Using several telescopes, including NASA's Chandra X-ray Observatory, researchers have found evidence that a white dwarf star - the dense core of a star like the Sun that has run out of nuclear fuel - may have ripped apart a planet as it came too close.

Today we released six new images from Chandra’s vast data archive. Each one of these astronomical images combines X-rays from Chandra with data from telescopes that detect different types of light such as infrared, radio, and visible light.

Every year, NASA's Chandra X-ray Observatory looks at hundreds of objects throughout space to help expand our understanding of the Universe. Ultimately, these data are stored in the Chandra Data Archive, an electronic repository that provides access to these unique X-ray findings for anyone who would like to explore them. With the passing of Chandra's 15th anniversary in operation on August 26, 1999, the archive continues to grow as each successive year adds to the enormous and invaluable dataset.

Note: An earlier version of this article appeared on Peter Edmonds' blog.

Recently, beautiful photos of auroras have been in the news. These colorful light shows were generated by solar storms, and provide a vivid demonstration of activity on the Sun affecting the Earth. The pummeling experienced by our home planet is an example of our one-way relationship with the Sun: it can have a noticeable effect on the Earth, but the Earth has a negligible effect on the Sun. Further afield in the galaxy, this isn't always the case. In a few other systems planets can have a big effect on their star, changing their looks in surprising ways.

A spectacular picture of auroras by photographer Mike Taylor taken over Unity Pond in Waldo County, Maine on September 12, 2014. Credit: Mike Taylor photography.

A new study using data from NASA's Chandra X-ray Observatory has shown that a planet is making the star that it orbits act much older than it actually is, as explained in our latest press release. The artist's illustration featured in the main part of this graphic depicts the star, WASP-18, and its planet, WASP-18b.

The Eta Carinae star system does not lack for superlatives. Not only does it contain one of the biggest and brightest stars in our galaxy, weighing at least 90 times the mass of the Sun, it is also extremely volatile and is expected to have at least one supernova explosion in the future.