Spin and Orbit

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As part of maintaining the Exoplanet Orbit Database, I update the orbital parameters of a planet when new results are published. Often, certain parameters are the focus of new papers, and one example is the spin-orbit misalignment of a system, recorded as "lambda" on exoplanets.org.

Professor Josh Winn of MIT has published many papers on spin-orbit misalignment. Naturally, his name is what I often put as the reference of the "lambda" field. When I found out that I could meet him while visiting my sister in Boston over spring break, there were some questions I just had to ask him.

Once he knew that I could meet Josh Winn, Dr. Wright gave me an explanation on what spin-orbit misalignment is and shared some fascinating stories about the research. Spin-orbit misalignment, "lambda," describes the angle between the rotational axis of the star and the orbital axis of the planet. Studying "lambda" can provide insight into planetary formation.

post 18 - spin-orbit 1.gif

Source - NAOJ

To measure "lambda," astronomers use the Rossiter-McLaughlin effect. Illustrated in the figure below, the planet's path across the star's disk influences the changes in the radial velocity curve of the star, which tells us whether the star appears to be approaching us or receding from us. The spin-orbit misalignment (or alignment) influences that trajectory.

post 18 - spin-orbit 2.gif

Source - NAOJ

Dr. Wright included some details of the progress Josh Winn and his team initially made and suggested that I ask Dr. Winn to share his anecdotes. As my sister is in one of his graduate courses, I joined her on a Friday lecture during my spring break. It turned out that, while my sister introduced me to him, I did not get to ask my questions, which were overshadowed by the excitement of the moment.

After break, I emailed him with the questions, and ended up exchanging a phone conversation - more convenient and less time consuming. Here is part of the research narrative of an astronomer:

Starting in 2005, Dr. Winn and his team began examining exoplanetary systems for spin-orbit alignment for exploratory purposes, wondering if there would be a surprise. The initial five or six systems observed were well-aligned, just like the case of our solar system. At that point, the telescope allocation committee argued that these observations took up quite an amount of time, and it was an expensive effort.

Is that it then?

Things fell into place when, around that time, the first case of misalignment was published by a European team on the planet XO-3 b. Josh Winn's team confirmed the findings, and they soon found more cases, including the first retrograde orbit system, HAT-P-7.

Despite the pressures from a committee, the results of that research continue to be fruitful. Such anecdotes are why research is far from mundane.

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My head is spinning so I won't even attempt to understand. @_@

Wow, your sister goes to MIT?

Networking! You lucky girl, you, getting all up close and personal with successful people in your field.

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