Star’s Cosmic Cloud Flickers

Infrared nebula around young star dims and brightens.

A giant cloud of gas and dust surrounding a baby star named IRAS 18148-0440 has been observed to change its brightness and shape. This phenomenon, visible only in infrared light, marks a significant discovery, as previously only nebulae visible in regular light were known to exhibit such flickering.

Research Methodology

Scientists meticulously studied the nebula for 17 years, utilizing telescopes equipped with special infrared cameras. They captured images on 11 different occasions, carefully measuring the cloud's light and comparing it to nearby stars.

Dramatic Changes Observed

The nebula's glow exhibited dramatic changes:

• Brightness Variation: Its brightness varied significantly, ranging from 9.8 to 12.0 over the 17-year period.
• Rapid Shifts: Surprisingly, the cloud's brightness could shift by a noticeable amount in as little as two months.

The scientists noted:

"The illumination of the nebula must be significantly and rapidly changing to show significant brightness changes on a time scale of, at most, four times longer than the light crossing time."

In addition to brightness changes, parts of the cloud were observed to vanish and then reappear in the same spots. This suggests that a large, opaque object is moving in front of the star, casting shadows that sweep across the nebula. The team hypothesizes that these changes are caused by opaque clouds orbiting very close to the star, effectively blocking its light like a cosmic dimmer switch.

Challenges and Future Prospects

The study faced several challenges due to the observations not being planned from the outset and the use of different instruments over many years. Despite these difficulties, this discovery reveals a new type of variable nebula, an infrared twin to the well-known blinking clouds seen in visible light. Future research will further explore similar flickering clouds to enhance our understanding of how young stars develop.

Reference:

Connelley, M. S., Hodapp, K. W., & Fuller, G. A. (2008). A Photometrically and Morphologically Variable Infrared Nebula in L483. arXiv preprint arXiv:0811.1232.