Barnard's Star : RV monitoring

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Barnard's Star : RV monitoring

Post by Edasich on 9th June 2009, 8:21 am

Wish it may be confirmed soon.

The UVES M Dwarf Planet Search

In the case of Barnard’s star we find a significant signal with a period of 44.9 d and an RV amplitude of ± 2.9 ms–1 (Zechmeister et al., 2009; Kürster et al. 2003). If this signal could be attributed to an orbiting companion, this object would be a Super-Earth with a minimum mass of 4.7 Me. It would orbit somewhat outside of the habitable zone of Barnard’s star.
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Re: Barnard's Star : RV monitoring

Post by Sirius_Alpha on 9th June 2009, 10:44 am

However, there are reasons to believe that the signal is produced by the star itself, i.e. by its surface activity and its influence on the convective motions that carry the heat transport from the interior to the outer regions of a low-mass star. When examining the line strength of the Hα line one finds the same 44.9 d periodicity. The Hα line originates in the stellar photosphere as an absorption line, but it has superimposed emission components generated in localised, so called “plage”, regions in the chromosphere, a higher and hotter layer of the stellar atmosphere.

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Re: Barnard's Star : RV monitoring

Post by Edasich on 10th June 2009, 4:42 am

*sigh* Sad

Maybe it's timelt to shift this in "Unconfirmed planets" thread, isn't it?
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Re: Barnard's Star : RV monitoring

Post by Sirius_Alpha on 10th June 2009, 8:06 am

I think Van de Kamp cursed the star somehow. It's probably the only one within 10 parsecs without any planetary companions. Laughing

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Re: Barnard's Star : RV monitoring

Post by ciceron on 10th June 2009, 8:30 am

No super-earths may be good news. It leaves room for a normal sized Earth Smile

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Re: Barnard's Star : RV monitoring

Post by Lazarus on 13th June 2009, 6:10 pm

I think the unconfirmed planets thread would be assigning far too much likelihood to this one Razz
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Re: Barnard's Star : RV monitoring

Post by Sirius_Alpha on 13th August 2012, 8:13 pm

Precise Doppler Monitoring of Barnard's Star
http://arxiv.org/abs/1208.2273

We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during 25 years between 1987 and 2012. The early precision was 20 \ms{} but was 2 \ms{} during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above $\sim$2 \ms{}, setting firm upper limits on the minimum mass (\msini) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 \mearth{} and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 \mearth{} (0.03 \mjup) are also ruled out. A similar analysis allowing for eccentric orbits yields comparable mass limits. The habitable zone of Barnard's Star appears to be devoid of roughly Earth-mass planets or larger, save for face-on orbits. Previous claims of planets around the star by van de Kamp are strongly refuted. The radial velocity of Barnard's Star increases with time at $4.515\pm0.002$ \msy{}, consistent with the predicted geometrical effect, secular acceleration, that exchanges transverse for radial components of velocity.


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Re: Barnard's Star : RV monitoring

Post by Lazarus on 14th August 2012, 1:24 pm

That's starting to get down to the range where the Kepler-42 planets (which orbit a very similar star to Barnard's Star) would possibly be detectable, nice.

Wonder whether the claims for planets around Lalande 21185 will hold up.
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25 years of doppler analysis of Barnard's star: results and HZ.

Post by Giangore on 7th January 2013, 1:33 pm

Here an interesting paper showing the results of 25 years of spectroscopic observation of Barnard's star.
Interesting results on the HZ also:

http://arxiv.org/abs/1208.2273


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Re: Barnard's Star : RV monitoring

Post by Sirius_Alpha on 7th January 2013, 1:44 pm

Giangore wrote:Here an interesting paper showing the results of 25 years of spectroscopic observation of Barnard's star.
Interesting results on the HZ also:

http://arxiv.org/abs/1208.2273
Merged.

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