Credit: ESA/Hubble & NASA.
Acknowledgement: Alexey Romashin
Acknowledgement: Alexey Romashin
The Universe is rarely static, although the timescales involved can
be very long. Since modern astronomical observations began we have been
observing the birthplaces of new stars and planets, searching for and
studying the subtle changes that help us to figure out what is happening
within.
The bright spot located at the edge of the bluish fan-shaped
structure in this Hubble image is a young star called V* PV Cephei, or
PV Cep. It is a favourite target for amateur astronomers because the
fan-shaped nebulosity, known as GM 1-29 or Gyulbudaghian’s Nebula,
changes over a timescale of months. The brightness of the star has also
varied over time.
Images of PV Cep taken in 1952 showed a nebulous streak, similar to a
comet’s tail. However, these had vanished when new images of the star
were obtained some twenty-five years later. Instead, the blue fan-shaped
nebula had appeared. Twenty-five years is a very short period on cosmic
timescales, so astronomers think that the mysterious streak may have
been a temporary phenomenon, such as the remnants of a massive stellar
flare — similar to the solar flares we are used to seeing in the Solar
System.
At the same time as this was happening, the star itself was
brightening. This provided the light to illuminate the newly formed
fan-shaped nebula. This brightening might be related to the start of the
hydrogen-burning phase of the star, which would mean that it was
reaching maturity.
PV Cep is thought to be surrounded by a disc of gas and dust, which
would stop light from escaping in all directions. The fan-like
appearance is therefore probably a result of starlight escaping from the
dust disc and projecting onto the nebula.
PV Cep is located in the northern constellation of Cepheus at a distance of over 1600 light-years from Earth.
A version of this image was entered into the Hubble’s Hidden Treasures competition by contestant Alexey Romashin.
Source: ESA/Hubble - Space Telescope
