51 Peg b atmosphere and characterisation

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51 Peg b atmosphere and characterisation

Post by Sirius_Alpha on 26th February 2013, 9:42 pm

Detection of molecular absorption in the dayside of exoplanet 51 Pegasi b?
http://arxiv.org/abs/1302.6242

In this paper we present ground-based high-resolution spectroscopy of 51 Pegasi using CRIRES at the Very Large Telescope. The system was observed for 3x5 hours at 2.3 {\mu}m at a spectral resolution of R = 100,000, targeting potential signatures from carbon monoxide, water vapour and methane in the planet's dayside spectrum. In the first 2x5 hours of data, we find a combined signal from carbon monoxide and water in absorption at a formal 5.9{\sigma} confidence level, indicating a non-inverted atmosphere. We derive a planet mass of M_P = (0.46 +- 0.02) M_Jup and an orbital inclination i between 79.6 and 82.2 degrees, with the upper limit set by the non-detection of the planet transit in previous photometric monitoring. However, there is no trace of the signal in the final 5 hours of data. A statistical analysis indicates that the signal from the first two nights is robust, but we find no compelling explanation for its absence in the final night. The latter suffers from stronger noise residuals and greater instrumental instability than the first two nights, but these cannot fully account for the missing signal. It is possible that the integrated dayside emission from 51 Peg b is instead strongly affected by weather. However, more data are required before we can claim any time variability in the planet's atmosphere.

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Detection of molecules in 51 Pegasi b?

Post by Edasich on 27th February 2013, 5:20 am

Detection of molecular absorption in the dayside of exoplanet 51 Pegasi b?

In this paper we present ground-based high-resolution spectroscopy of 51 Pegasi using CRIRES at the Very Large Telescope. The system was observed for 3x5 hours at 2.3 {\mu}m at a spectral resolution of R = 100,000, targeting potential signatures from carbon monoxide, water vapour and methane in the planet's dayside spectrum. In the first 2x5 hours of data, we find a combined signal from carbon monoxide and water in absorption at a formal 5.9{\sigma} confidence level, indicating a non-inverted atmosphere. We derive a planet mass of M_P = (0.46 +- 0.02) M_Jup and an orbital inclination i between 79.6 and 82.2 degrees, with the upper limit set by the non-detection of the planet transit in previous photometric monitoring. However, there is no trace of the signal in the final 5 hours of data. A statistical analysis indicates that the signal from the first two nights is robust, but we find no compelling explanation for its absence in the final night. The latter suffers from stronger noise residuals and greater instrumental instability than the first two nights, but these cannot fully account for the missing signal. It is possible that the integrated dayside emission from 51 Peg b is instead strongly affected by weather. However, more data are required before we can claim any time variability in the planet's atmosphere.

If confirmed, this could well bode for planetary nature of 51 Peg b (somehow already inferred by host star's chromospheric and X-ray activity analysis).

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Re: 51 Peg b atmosphere and characterisation

Post by Sirius_Alpha on 27th February 2013, 7:57 am

Merged.

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Re: 51 Peg b atmosphere and characterisation

Post by Edasich on 27th February 2013, 8:13 am

Sirius_Alpha wrote:Merged.

Oops. Shocked

Detection of molecular absorption in the dayside of exoplanet 51 Pegasi b?

Anyway, interesting clues from transit non detection.

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Re: 51 Peg b atmosphere and characterisation

Post by Lazarus on 27th February 2013, 12:37 pm

The inclination close to 90 degrees seems to fit with the polarimetry claims discussed in this thread.

Reading that thread, I also seem to remember something about claims of an evaporating atmosphere being detected for 51 Peg b, not sure where though.

Nice to see that 51 Peg is still getting some attention, the detection of transiting hot Jupiters seems to have caused it to be neglected a bit... maybe we will finally know the true mass of the first (candidate?) exoplanet discovered around a Sunlike star.

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