Tau Boo atmosphere detected directly from Earth

New Way of Probing Exoplanet Atmospheres

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For the first time a clever new technique has allowed astronomers to study the atmosphere of an exoplanet in detail — even though it does not pass in front of its parent star. An international team has used ESO’s Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b. They have studied the planet’s atmosphere and measured its orbit and mass precisely for the first time — in the process solving a 15-year old problem. Surprisingly, the team also finds that the planet’s atmosphere seems to be cooler higher up, the opposite of what was expected. The results will be published in the 28 June 2012 issue of the journal Nature.

Direct detection was claimed in '99, but nice they finally managed to do it for certain.

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Seeing the planet’s light directly has allowed the astronomers to measure the angle of the planet’s orbit and hence work out its mass precisely. By tracing the changes in the planet’s motion as it orbits its star, the team has determined reliably for the first time that Tau Boötis b orbits its host star at an angle of 44 degrees and has a mass six times that of the planet Jupiter in our own Solar System.

Seems that this was determined indirectly already.

Nice to see this, sometimes it seems that the first few exoplanets are a bit neglected in these days of transiting planets.

Perhaps it may not be too long before the true mass of 51 Pegasi b will also finally be known.

Weighing The Non-Transiting Hot Jupiter Tau BOO b
http://arxiv.org/abs/1206.6197

The signature of orbital motion from the dayside of the planet tau Bootis b
http://arxiv.org/abs/1206.6109

I guess that makes Tau Boötis A the second example of a double-lined spectroscopic binary where one object is a planet, the first being HD 209458.

Near-IR Direct Detection of Water Vapor in Tau Boo b
http://arxiv.org/abs/1402.0846

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We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity variations of the hot Jupiter in the tau Bootis planetary system. The detection of an exoplanet by the shift in the stellar spectrum alone provides a measure of the planet's minimum mass, with the true mass degenerate with the unknown orbital inclination. Treating the tau Boo system as a high flux ratio double-lined spectroscopic binary permits the direct measurement of the planet's true mass as well as its atmospheric properties. After removing telluric absorption and cross-correlating with a model planetary spectrum dominated by water opacity, we measure a 6-sigma detection of the planet at K_p = 111 +- 5 km/s, with a 1-sigma upper limit on the spectroscopic flux ratio of 10^-4. This radial velocity leads to a planetary orbital inclination of i = 45+3-4degrees and a mass of M_P = 5.90+0.35-0.20 M_ Jup. We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, tau Boo b.

Not quite the same subject, but there doesn't seem to be a more fitting Tau Boötis thread.

The GAPS Programme with HARPS-N at TNG. VII. Putting exoplanets in the stellar context: magnetic activity and asteroseismology of τ Bootis A

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Aims. We observed the τ Boo system with the HARPS-N spectrograph to test a new observational strategy aimed at jointly studying asteroseismology, the planetary orbit, and star-planet magnetic interaction. Methods. We collected high-cadence observations on 11 nearly consecutive nights and for each night averaged the raw FITS files using a dedicated software. In this way we obtained spectra with a high signal-to-noise ratio, used to study the variation of the CaII H&K lines and to have radial velocity values free from stellar oscillations, without losing the oscillations information. We developed a dedicated software to build a new custom mask that we used to refine the radial velocity determination with the HARPS-N pipeline and perform the spectroscopic analysis. Results. We updated the planetary ephemeris and showed the acceleration caused by the stellar binary companion. Our results on the stellar activity variation suggest the presence of a high-latitude plage during the time span of our observations. The correlation between the chromospheric activity and the planetary orbital phase remains unclear. Solar-like oscillations are detected in the radial velocity time series: we estimated asteroseismic quantities and found that they agree well with theoretical predictions. Our stellar model yields an age of 0.9 ± 0.5 Gyr for τ Boo and further constrains the value of the stellar mass to 1.38 ± 0.05 M_⊙.

Borrowing from what Lazarus said, Tau Boö is not a system that receives much study compared to the "big-name" Hot Jupiters, which is a bit of a shame. So, this paper is good to see.

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The model we built allowed us to further constrain the value of the stellar mass to 1.38 ± 0.05 M_⊙ and thus, using i = 44.5 ± 1.5^◦
(Brogi et al. 2012), the mass of the planet to 6.13 ± 0.17 M_Jup.

As spectroscopic resolution of atmospheric absorption lines in Hot Jupiters becomes more commonplace, we will hopefully see many more direct derivations of planetary inclinations and masses in the near future.

Attempting to detect Tau Boötis b in the optical:

Hoeijmakers, Snellen & Terwisga "Searching for reflected light from τ Bootis b with high-resolution ground-based spectroscopy: Approaching the 10−5 contrast barrier"
https://arxiv.org/abs/1711.05334

From the 3σ upper limit on the planet-to-star contrast, the upper limit on the geometric albedo is 0.12 between 400 and 700 nm.