Variable Star HP Tau Revisited | Hubble Space Telescope

Variable Star HP Tau Revisited | Hubble Space Telescope

Looking like a glittering cosmic geode, a trio of dazzling stars blaze from the hollowed-out cavity of a reflection nebula. The triple-star system is made up of the variable star HP Tau, HP Tau G2, and HP Tau G3. HP Tau is known as a T Tauri star, a type of young variable star that has not begun nuclear fusion yet but is beginning to evolve into a hydrogen-fueled star similar to our Sun. T Tauri stars tend to be younger than 10 million years old―in comparison, our Sun is around 4.6 billion years old―and are often found still swaddled in the clouds of dust and gas they were formed from.

As with all variable stars, HP Tau’s brightness changes over time. T Tauri stars are known to have periodic and random fluctuations in brightness. The random variations may be due to the chaotic nature of a developing young star, such as instabilities in the accretion disk of dust and gas around the star, material from that disk falling onto the star and being consumed, and flares on the star’s surface. The periodic changes may be due to giant sunspots rotating in and out of view.

Curving around the stars, a cloud of gas and dust shines with their reflected light. Reflection nebulae do not emit visible light of their own, but shine as the light from nearby stars bounces off the gas and dust, like fog illuminated by the glow of a car’s headlights.

HP Tau is located approximately 550 light-years away in the constellation Taurus. Hubble studied HP Tau as part of an investigation into protoplanetary disks, the disks of material around stars that coalesce into planets over millions of years.

Image Processor Judy Schmidt: "I was looking at this image at the nasa.gov website and wondering why it turned out like it did. It's a low signal image firstly, but secondly, when trying to bring out that low signal, the fringe pattern (Figure 5.4) in the F814W data becomes a big problem. I did away with the fringe pattern by using the F606W data for luminance in all the low signal areas. If you're into graphic design you might be more familiar with fringe patterns by the name of Moiré."

"Other things of note: The chip gap is filled with cloned data. There are some old WFPC2 data in the archive that could have filled some of it, but it didn't seem worth it. I did use some rather heavy noise reduction, or at least I personally consider it heavy, but the image is still pretty noisy. That's just how it is. I don't think a better image results from trying to make it any smoother."

Image Credit: ESA/NASA/Space Telescope Science Institute (STScI)/Judy Schmidt
Release Date: Aug. 13, 2025

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