Astronomers Discover the First Known Green Star
Astronomers are excited about the news that the first green star has been identified. What does it mean, and why is the news so historic? Read on for all of the details of this celestial discovery.
Scientists Identify First Green Star
A new study published in the journal RAS Techniques and Instruments details that astronomers researching white dwarf stars have discovered the first green star. White dwarfs are what astronomers use to define the remnants of sun-like stars that have died. Up until now, there has never been a green star observed.
According to lead study author Mark Hollands, an astrophysicist at the University of Warwick, England, color is dependent on temperature for most stars. Hollands explains that, "The colors that normal stars can have are pretty much only orange, white or blue."
However, white dwarf stars can take on a wide variety of colors. According to Hollands, "there are some special cases where the physics in the outer layers of these stars are sufficiently strange that it causes actually quite big deviations in terms of their spectrum."
The changes in colors happen as a result of the interaction between the helium in the star's atmosphere and other elements. Each white dwarf star is unique in the material that it has interacted with throughout its lifetime, making the color combinations more vast.
For example, traces of iron, sodium, or magnesium on the surface of the star indicate that an asteroid may have come close to the white dwarf. The bits of the asteroid can land on the white dwarf, becoming parts of its debris field. Hollands explains, “And then that gets mixed into the outer layers, and then you can actually use that to measure what the rocky stuff was made of." As such, white dwarfs can be used as a tool to look at the chemistry of planetary material and how it interacts with different elements.
The newly identified green star is named WD J1330+6435. The star is located in the Milky Way galaxy in the constellation Draco.
About the Composition of This Green Star
Hollands and his team examined the 151 known white dwarf stars that are located within 65 light-years of Earth. The green star presented with primary elements of calcium, sodium, and lithium. A different star appeared a salmon pink color, attributed to its high density of carbon. This star is now thought to be the reddest star ever identified.
White dwarf stars are not visible from Earth. However, Hollands was able to determine their colors using star spectrum data, a set of metrics defined by the researchers as “the ‘fingerprint’ produced when starlight is split apart by wavelength, much like a prism splits sunlight into a rainbow.”
The discovery that temperatures and atmospheric properties can be used to determine star colors may prove useful moving forward. By organizing this data, scientists can conclude how to classify other objects based on their specific composition.
Hollands and his team are now planning to analyze white dwarf star spectra. The knowledge gleaned from this recent study will hopefully give astronomers the ability to look at stars that are even farther away from Earth.
As Hollands notes, “We know of white dwarfs that we don’t have spectra for, but that’s all about to change because there are quite a few spectroscopic surveys” that will start spitting out data that scientists can use for further analysis. “We’ll be getting a tenfold increase in the number of white dwarfs that have spectra. And so maybe if we’re lucky, we’ll go from one or maybe two green white dwarfs to 10 or 20," he said.
Hollands concluded by saying that the discovery of a green star like in the movies shows "that the universe is sometimes just as weird as anything science fiction can conjure up."
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