Upsilon Andromedae b polarimetry

View previous topic View next topic Go down

Upsilon Andromedae b polarimetry

Post by Sirius_Alpha on 14th September 2011, 10:49 pm

Upsilon Andromedae b in polarized light: New constraints on the planet size, density and albedo
http://arxiv.org/abs/1109.3116

Polarimetry is a novel tool to detect and characterize exoplanets and their atmospheres. Polarized scattered light from the non-transiting hot Jupiter $\upsilon$~And~b is measured to further constrain its orbit, mass, density, and geometrical albedo. We obtained polarimetric measurements in the $UBV$ bands over the orbital period and deduce an average peak-to-peak amplitude of $(49 \pm 5)\times10^{-6}$ in both Stokes $q$ and $u$. From our data we evaluate the orbit inclination $i=111\degr\pm11\degr$, longitude of the ascending node $\Omega=236\degr\pm12\degr$ (or equivalently 56\degr), the effective size of the scattering atmosphere in the optical blue of $1.36\pm0.20$\,$R_{\rm J}$. These combined with spectroscopic measurements result in the planet mass $0.74\pm0.07$\,$M_{\rm J}$, mean density $0.36\pm0.08$\,g\,cm$^{-3}$, and surface gravity $\sim10^3$\,cm\,s$^{-2}$, which favor a close similarity of $\upsilon$~And~b to other inflated hot Jupiters. We also significantly improved the periastron epoch $T_{\rm p}={\rm JD}2,450,032.451$, interior conjunction epoch $T_{\rm t}={\rm JD}2,450,034.668$, and periastron longitude $\omega=279\degr\pm14\degr$. The latter indicates that the apsidal resonance known for planets c and d includes also planet b.
Obtained limits on the wavelength dependent geometrical albedo (average 0.35) indicate its similarity to Neptune with peak reflectivity in the blue. Combining all available measurements at various passbands, we construct a unified wavelength dependent albedo of an average hot Jupiter. It appears to be largely shaped by Rayleigh scattering in the blue and atomic and molecular absorption in the optical and near infrared. Our findings demonstrate the power of polarimetry for studying non-transiting exoplanets.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3494
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Upsilon Andromedae b polarimetry

Post by tommi59 on 15th September 2011, 3:23 am

Great tool. I did not expect to know density of ups and b due to lack of transit.I hope next systems will be gj 581,876 please.I have a question to you sirius is it possible to use polarimetry to longer period 20-100 days planet whether only close in non transiting?


Last edited by tommi59 on 15th September 2011, 4:00 am; edited 1 time in total
avatar
tommi59
Jovian
Jovian

Number of posts : 548
Age : 39
Location : Baile Atha Cliath
Registration date : 2010-07-31

View user profile

Back to top Go down

Re: Upsilon Andromedae b polarimetry

Post by Lazarus on 15th September 2011, 3:59 am

Excellent, going to have to try modelling this in Celestia with the astrometric orbits for c and d.
avatar
Lazarus
dG star
dG star

Number of posts : 2845
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Upsilon Andromedae b polarimetry

Post by Sirius_Alpha on 15th September 2011, 7:23 am

tommi59 wrote:I have a question to you sirius is it possible to use polarimetry to longer period 20-100 days planet whether only close in non transiting?

I don't know why it wouldn't be possible in principle. Of course the longer the period of the planet, the dimmer it will be and the harder it will be to pull off.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3494
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: Upsilon Andromedae b polarimetry

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum