Deep Space Nebula Mysteriously Flashes and Morphs
Astronomers observe a stellar nursery changing dramatically over time.
A deep space nebula surrounding a young star dramatically changes brightness and shape, according to new research.
Astronomers peered into the L483 dark cloud to study IRAS 18148-0440, a young stellar object (YSO), which is a star still in its early formation stages. They focused on the infrared nebula, a cloud of gas and dust glowing brightly in infrared light, that surrounds this cosmic infant. The question was: Does this infrared nebula, like some visible-light ones, change over time?
The Long-Term Study
The long-term study spanned 17 years, collecting data across 11 different observation times. Researchers used various telescopes and instruments, including QUIRC, SpeX, and 2MASS, essentially different "cameras" that can see in infrared. They measured the nebula's brightness by comparing it to steady background stars.
Striking Findings
The findings were striking:
- The nebula's brightness, measured as K-band magnitude, swung widely from 9.8 to 12.0 over 17 years.
- Even more surprising, its brightness changed by about 1 magnitude in just two months. Imagine a light dimmer knob turning itself up and down!
- The nebula also morphed its shape, with glowing features appearing and disappearing in the same spot.
"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," the study authors explain.
The "light crossing time" is like how long it takes light to travel from one end of the nebula to the other, about 17 days.
This variability likely comes from changes in how the central young star lights up the surrounding cloud, perhaps due to shadowy clouds moving close to the star. This makes IRAS 18148-0440 a cosmic twin to famous variable nebulae seen in visible light, like Hubble’s Variable Nebula.
Considerations and Future Research
- The study used different instruments over time, which could slightly affect precise brightness comparisons.
- The observations were not initially planned as a continuous monitoring effort.
Future research will surely hunt for more of these surprising, flickering infrared nebulae around other young stars. The universe, it turns out, is a much more dynamic place than we often imagine.
Reference:
Connelly et al. (2008), A Photometrically and Morphologically Variable Infrared Nebula in L483, arXiv:0811.1232v1 [astro-ph]