Iron detected in the dayside atmosphere of ultra-hot Jupiter MASCARA-5 b confirms thermal inversion

Star system: HD 201033 | Distance from the Sun: 488 light years

MASCARA-5 b (also known as TOI-1431 b) is an ultra-hot Jupiter orbiting a bright Am star. Using the EXPRES spectrograph, scientists confirmed the presence of neutral iron (Fe I) in the planet's dayside atmosphere with high significance. The detection supports previous findings and indicates that the planet's atmosphere is thermally inverted, with temperatures rising from about 2000 K at lower altitudes to around 4500 K higher up.

No evidence was found for ionized iron (Fe II) or neutral chromium (Cr I). The Fe I signal also shows a blueshift, which may be caused by winds in the planet's atmosphere. These results demonstrate that MASCARA-5 b is an excellent target for atmospheric studies using emission spectroscopy, allowing researchers to probe its chemistry, temperature structure, and atmospheric dynamics.

The findings highlight the power of high-resolution spectroscopy for characterizing the atmospheres of ultra-hot Jupiters and provide new insights into the thermal and chemical properties of these extreme worlds.

Key findings
- Fe I detected in the dayside atmosphere of MASCARA-5 b
- The atmosphere is thermally inverted, with temperatures from 2000 K to 4500 K
- No detection of Fe II or Cr I
- Fe I signal shows a blueshift, possibly due to winds
- MASCARA-5 b is ideal for detailed atmospheric characterization

Scientific study

Confirmation of Fe I on MASCARA-5 b's Dayside Observed With EXPRES (external link)