XO-3 b's near-UV transit reveals deeper absorption and timing offset

Star system: XO-3 | Distance from the Sun: 658 light years

Researchers observed the near-UV (NUV) transit of XO-3 b, a massive hot Jupiter with an eccentric orbit, using XMM-Newton and ground-based telescopes. The NUV transit was found to be 30-70% deeper than in the optical, suggesting a large NUV-absorbing atmosphere. Interestingly, the NUV transit occurred about 22 minutes later than expected from optical data, even though the optical transits showed no timing variations.

The team explored possible causes for these findings. X-ray data revealed a very low atmospheric mass-loss rate, making atmospheric escape an unlikely explanation for the deep NUV absorption. They also considered whether a magnetic bow-shock could cause the timing offset, but their calculations predicted an early, not late, transit. This suggests that more detailed simulations are needed to understand the NUV behavior of XO-3 b.

Key findings
- XO-3 b's NUV transit is significantly deeper than the optical transit
- The NUV transit occurs about 22 minutes later than expected
- Atmospheric escape is unlikely to explain the deep NUV absorption
- Magnetic bow-shock models predict an early, not late, transit
- Further simulations are needed to explain the observations

Scientific study

The NUV transit of XO-3 b (external link)