51 Peg b atmosphere and characterisation

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

Quote :

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.

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

Quote :

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).

Merged.

Sirius_Alpha wrote:

Merged.

Oops.

Quote :

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

Anyway, interesting clues from transit non detection.

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.

Do we have any paper reference about radius of 51 pegasi b 1.03 j?

They got it from this paper, which lists a number of planets and assigns them radius estimates based on Fortney et al.

EPE is listing a forthcoming A&A paper about this, Martins et al. (2015) "Evidence for a spectroscopic direct detection of reflected light from 51 Pegasi b"

So far I haven't seen an arXiv version.

EPE's page on 51 Peg b says "Based on the detection of a planet to star reflected flux ratio of 6.0 ± 0.4 x 10^-5 and assumed radius 1.9 RJup, Martins et al. 2015 find a planet albedo of 0.5."

1.9 R_J seems a little extreme. As does an albedo of 0.5, though that does sound like a sensible value for a reflected light signal of 60 ppm. If that's what "reflected flux ratio" is equivalent to, anyway.

I imagine we'll be seeing this on arxiv soon.

That would put it right at the upper end of the range of observed hot Jupiter sizes, there are only a couple of known transiting planets with radii larger than that. According to the NASA list, only the companions to GQ Lupi and CT Chamæleontis have radii that are substantially larger, and they are both young (of the order 1 Myr) objects above the deuterium-burning threshold.

http://www.eso.org/public/usa/news/eso1517/

http://www.eso.org/public/archives/releases/sciencepapers/eso1517/eso1517a.pdf

Evidence for a spectroscopic direct detection of reflected light from 51 Peg b

http://arxiv.org/abs/1509.00723

Detecting ring systems around exoplanets using high resolution spectroscopy: the case of 51Pegb

In this paper we explore the possibility that the recently detected reflected light signal of 51\,Peg\,b could be caused by a ring system around the planet. We use a simple model to compare the observed signal with the expected signal from a short-period giant planet with rings. We also use simple dynamical arguments to understand the possible geometry of such a system. We provide evidence that, to a good approximation, the observations are compatible with the signal expected from a ringed planet, assuming that the rings are non-coplanar with the orbital plane. However, based on dynamical arguments, we also show that this configuration is unlikely. In the case of coplanar rings we then demonstrate that the incident flux on the ring surface is about 2\% the value received by the planet, a value that renders the ring explanation unlikely. The results suggest that the signal observed cannot in principle be explained by a planet+ring system. We discuss, however, the possibility of using reflected light spectra to detect and characterize the presence of rings around short-period planets. Finally, we show that ring systems could have already been detected by photometric transit campaigns, but their signal could have been easily misinterpreted by the expected light curve of an eclipsing binary.

Water on 51 Pegasi b, somewhat wider inclination constraint (70°<i<82°).

Birkby et al. "Discovery of water at high spectral resolution in the atmosphere of 51 Peg b"
https://arxiv.org/abs/1701.07257

Or maybe not!

The GAPS Programme at TNG. XXX. No detection of reflected light from 51~Peg~b using optical high-resolution spectroscopy
https://arxiv.org/abs/2012.10435