Direct imaging discovery of a planet around a young A8 star

Image credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin
eso1324aA new, 4 – 5 Jupiter mass probable planet discovery has been reported today around the young (10 – 17 Myr) dusty A8 star HD 95086. The companion is detected in the L’ band at 3.8 microns (left, image courtesy ESO/J. Rameau) using the NACO adaptive optics instrument at the ESO VLT. The best detection has a signal-to-noise ratio of 9. The projected separation is 56 AU and the planet is still warm, with surface temperature is around 1000K. The model-dependent mass obtained means this companion is the lightest planet yet directly imaged. The star lies close to the galactic plane as can easily be seen in the main image of the field around HD 95086, but contamination of the detection by a background object is unlikely, and the planetary status of the companion is reinforced by a non-detection in the Ks band (2.18 microns). The astrometry confirms it is co-moving with the star. The paper is “Discovery of a probable 4-5 Jupiter-mass exoplanet to HD 95086 by direct-imaging”, J. Rameau et al., arXiv preprint [pdf], and is accepted to ApJ letters.

In another new development, NASA have shown that the closest red dwarf, Proxima Centauri, will pass close to two background stars in alignments in 2014 and again in 2016 (below) which will allow possible planets around Proxima to be detected by microlensing, as well as yielding an accurate mass measurement for the star itself:

Microlensing occurs when a foreground star passes close to our line of sight to a more distant background star. These images of the background star may be distorted, brightened and multiplied depending on the alignment between the foreground lens and the background source. These microlensing events, ranging from a few hours to a few days in duration, will enable astronomers to measure precisely the mass of this isolated red dwarf. Getting a precise determination of mass is critical to understanding a star’s temperature, diameter, intrinsic brightness, and longevity. Astronomers will measure the mass by examining images of each of the background stars to see how far the stars are offset from their real positions in the sky. The offsets are the result of Proxima Centauri’s gravitational field warping space. The degree of offset can be used to measure Proxima Centauri’s mass. The greater the offset, the greater the mass of Proxima Centauri. If the red dwarf has any planets, their gravitational fields will produce a second small position shift.

Image credit: NASA, ESA, K. Sahu and J. Anderson (STScI), H. Bond (STScI and Pennsylvania State University), M. Dominik (University of St. Andrews), and Digitized Sky Survey (STScI/AURA/UKSTU/AAO). The scalloped appearance of the path of the star is due to the Earth’s orbital motion.

There is more to read on highly accurate astrometry and microlensing, as well as direct imaging, in a new article from Space Review on the specifications and exoplanet detection capabilities of WFIRST-2.4, while for those who prefer more conceptual reading, there is another article about loop quantum gravity and the resolution of black hole singularities. The paper under discussion is Gambini & Pullin, “Loop quantisation of the Schwarzschild black hole”, in Phys. Rev. Lett., (arXiv), the essential idea being that LQG can provide a mathematical description applicable to both black holes and the early Universe which is able to remove (resolve) the problematic singularity introduced by general relativity in both cases.


One Response to “Direct imaging discovery of a planet around a young A8 star”

  1. […] data over 30,000 square degrees by Best et al., in arXiv today. Lastly, from the same source, the companion to HD 95086 appears ever more planet-like with its non-detection in the near-infrared H-band (1.6 microns) […]

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