A gas giant around Epsilon Indi !!

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A gas giant around Epsilon Indi !!

Post by Sirius_Alpha on 22nd March 2018, 8:35 pm

Detection of the closest Jovian exoplanet in the Epsilon Indi triple system
https://arxiv.org/abs/1803.08163

We confirm the trend in the radial velocity data for Epsilon Indi A suggesting a long-period planetary companion and find significant curvature is present, sufficient to quantify Epsilon Indi Ab as a cold Jupiter with a minimum mass of 2.71+2.19−0.44 MJup on a nearly circular orbit with a semi-major axis of 12.82+4.18−0.71 au and an orbital period of 52.62+27.70−4.12 yr. We also identify other significant signals in the radial velocity data. We investigate a variety of spectral diagnostics and interpret these signals as arising from activity-induced radial velocity variations. In particular, the 2500 and 278 d signals are caused by magnetic cycles. While a planetary signal might be present in the 17.8 d signal, the origin of 17.8 and 11 d signals are most easily interpreted as arising in the rotation of the star with a period of about 35 d. We find that traditional activity indicators have a variety of sensitivities. In particular, the sodium lines and CaHK index are sensitive to all activity-induced signals. The line bisector measurement is sensitive to stellar rotation signal while Hα is sensitive to the secondary magnetic cycle. In general, because of their different sensitivities these activity indicators introduce extra noise if included in the noise model whereas differential RVs provide a robust proxy to remove wavelength-dependent noise efficiently. Based on these analyses, we propose an activity diagnostics procedure for the detection of low amplitude signals in high precision radial velocity data. Thus the Epsilon Indi system comprises of at least Epsilon Indi A, Ab as well as a long period brown dwarf binary Ba and Bb; so it provides a benchmark case for our understanding of the formation of gas giants and brown dwarfs.

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Re: A gas giant around Epsilon Indi !!

Post by Edasich on 23rd March 2018, 4:52 am

The exclamation marks are more than justified. I share the joy! Very Happy cheers
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Re: A gas giant around Epsilon Indi !!

Post by Lazarus on 24th March 2018, 6:51 am

Interesting, this one's been kicking around for a long time.

I note the reference they give for the age of the star doesn't appear to mention Epsilon Indi. It does give a value for Epsilon Eridani which matches the 1.4 Gyr they put in the paper though.

From what I can tell, Epsilon Indi Bab should be close to having completed a full orbit since the binarity was discovered. Hopefully there will be some new orbital elements published soon, the preliminary orbit from 2010 doesn't give values for ω or Ω.

EPE appears to have made an error of a factor of 365-or-so in the orbital period...
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Re: A gas giant around Epsilon Indi !!

Post by Led_Zep on 4th April 2018, 2:28 pm

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Re: A gas giant around Epsilon Indi !!

Post by Lazarus on 27th July 2018, 10:36 am

Lazarus wrote:From what I can tell, Epsilon Indi Bab should be close to having completed a full orbit since the binarity was discovered. Hopefully there will be some new orbital elements published soon, the preliminary orbit from 2010 doesn't give values for ω or Ω.
So here's the update to the Epsilon Indi brown dwarfs (referred to here as B and C instead of Ba and Bb)

Dieterich et al. "Dynamical Masses of Eps Ind B and C: Two Massive Brown Dwarfs at the Edge of the Stellar-Substellar Boundary"
https://arxiv.org/abs/1807.09880

The masses are surprisingly high, an indication that our knowledge of the stellar/substellar boundary is incomplete.
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Re: A gas giant around Epsilon Indi !!

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