A new study unveils NGC 604, the largest region of star formation in the nearby galaxy M33, in its first deep, high-resolution view in X-rays. This composite image from Chandra X-ray Observatory data (colored blue), combined with optical light data from the Hubble Space Telescope (red and green), shows a divided neighborhood where some 200 hot, young, massive stars reside.
Throughout the
cosmic metropolis, giant bubbles in the cool
dust and warm gas are filled with diffuse,
multi-million degree gas that emits X-rays.
Scientists think these bubbles are generated and
heated to X-ray temperatures when powerful
stellar winds from the young massive stars
collide and push aside the surrounding gas and
dust. So, the vacated areas are immediately
repopulated with the hotter material seen by
Chandra.
However, there is a difference between the two
sides of this bifurcated stellar city. On the
western (right) side, the amount of hot gas
found in the bubbles corresponds to about 4300
times the mass of the sun. This value and the
brightness of the gas in X-rays imply that the
western part of NGC 604 is entirely powered by
winds from the 200 hot massive stars.
This result is interesting because previous modeling of other bubbles usually predicted them to be fainter than observed, so that additional heating from supernova remnants is required. The implication is that in this area of NGC 604, none or very few of the massive stars must have exploded as supernovas.
The situation is different on the eastern (left) side of NGC 604. On this side, the X-ray gas contains 1750 times the mass of the sun and winds from young stars cannot explain the brightness of the X-ray emission. The bubbles on this side appear to be much older and were likely created and powered by young stars and supernovas in the past.
