Eyes On A Distant World

In Exoplanets by Brian Koberlein6 Comments

A new planet has been discovered orbiting a star 1,200 light years away. While exoplanets are discovered all the time these days, this one was discovered by direct observation. You can see it in the image as the small brown dot to the upper left of the bluish central star. It’s kind of amazing that we can see it directly, but it’s also kind of amazing that it exists at all. 

The new planet orbits a star known as CVSO 30. It has a mass of about 5 Jupiters, and orbits the star at a distance of about 660 AU, with an orbital period of about 27,000 years. It’s large size and distance is the reason we can observe it directly. CVSO 30 is known to have at least one other planet, which orbits the star about every 10 hours.

What’s interesting is that CVSO 30 is a T-Tauri star, and still in the process of forming. It’s unlikely that such a large planet could have formed in its current location, so it is probably the product of a close interaction with another planetary body. It likely formed much closer to the star, and then was thrown into it’s current wide orbit. It’s a good example of just how dynamic early solar systems can be.

Paper: T. O. B. Schmidt, et al. Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30arXiv:1605.05315 [astro-ph.EP] (2016)


  1. Probably also worth noting that while both the star and planet appear to be resolved as round objects in this image, both are point sources and neither one is actually larger than a fraction of a pixel.

  2. Nice result, but despite the efforts the authors made to rule out possibilities other than an orbiting planet, I think the case is still somewhat open.

    Sure, it’s unfortunate that the object was in a diffraction spike, and yes, they made heroic efforts to get good data anyway, but I think it’s far from convincing. Also, as the ‘common proper motion’ test is not possible (neither object seems to have detectable proper motion), ruling out an unrelated object, with no detectable proper motion, is indirect. Finally, if both star and putative orbiting planet are young, the ‘standard object type’ tests can’t be all that definitive … young objects evolve rapidly.

    1. Author

      Yeah, it’s good to be skeptical about this one. For anything that is 660 AU out, determining whether it is gravitationally bound is tricky.

  3. My first thought was, how do they know they planet is not being ejected from the system. Any estimate on how long it would take to conclusively show that it is gravitationally bound?

  4. While some indirect tests may be possible within a year or so, and something can always come out of the blue, direct tests to show it’s gravitationally bound may take decades … you need proper motion, and preferably also radial velocity, both of which are really challenging for this object.

  5. With such a long orbital period and radius, a large mass, and considering that the ‘parent’ star is still in the process of formation, is it possible that this object was captured from another system or is a ‘rogue planet’ that happened to stray too close to the star’s gravitational influence? If it is indeed gravitationally bound, as discussed in the above comments.

Leave a Reply