Transit timing variations at TrES-2?

View previous topic View next topic Go down

Transit timing variations at TrES-2?

Post by Sirius_Alpha on 18th December 2008, 9:10 pm

http://arxiv.org/abs/0812.3549

Quote from the discussion:

The deviations to both sides of zero could be a first indication of timing anomalies caused by additional planets or moons. We will continue observing TrES-2 to confirm these transit time variations. Therefore, we work on methods to improve the accuracy of our transit times.

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Sirius_Alpha on 26th May 2009, 8:15 am

Detection of orbital parameter changes in the TrES-2 exoplanet ?
http://arxiv.org/abs/0905.4030

Abstract wrote:We report a possible change in the orbit parameters of the TrES-2 exoplanet. With a period of 2.470621 days, the TrES-2 exoplanet exhibits almost "grazing" transits 110.4 minutes duration as measured in 2006 by Holman and collaborators. We observed two transits of TrES-2 in 2008 using the 1.2m Oskar-Luhning telescope (OLT) of Hamburg observatory employing CCD photometry in an i-band and a near to R-band filter. A careful light curve analysis including a re-analysis of the 2006 observations shows that the current transit duration has shortened since 2006 by ~ 3.16 minutes. Although the new observations were taken in a different filter we argue that the observed change in transit duration time cannot be attributed to the treatment of limb darkening. If we assume the stellar and planetary radii to be constant, a change in orbit inclination is the most likely cause of this change in transit duration.

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Sirius_Alpha on 12th July 2009, 8:25 pm

On the Apparent Orbital Inclination Change of the Extrasolar Transiting Planet TrES-2b
http://arxiv.org/abs/0907.1685

On June 15, 2009 UT the transit of TrES-2b was detected using the University of Arizona's 1.55 meter Kuiper Telescope with 2.0-2.5 millimag RMS accuracy in the I-band. We find a central transit time of T_c = 2454997.76286 +/- 0.00035 HJD, an orbital period of P = 2.4706127 +/- 0.0000009 days, and an inclination angle of i = 83.92 +/- 0.05 degrees, which is consistent with our re-fit of the original I-band light curve of O'Donovan et al. (2006) where we find i = 83.84 +/- 0.05 degrees. We calculate an inclination change of Delta i = -0.08 +/- 0.071 degrees over the last 3 years, and as such, our observations rule out, at the ~11 sigma level, the apparent change of orbital inclination to i_predicted = 83.35 +/- 0.1 degrees as predicted by Mislis & Schmitt (2009) for our epoch. Indeed, we detect no significant changes in any of the orbital parameters of TrES-2b when comparing the original I-band light curve to our recent I-band light curve.

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Sirius_Alpha on 22nd December 2009, 9:10 pm

Further evidence for changes in the inclination of the orbit of the planet.

Multi-band transit observations of the TrES-2b exoplanet

http://arxiv.org/abs/0912.4428
Abstract wrote:We present a new data set of transit observations of the TrES-2b exoplanet taken in spring 2009, using the 1.2m Oskar-Luhning telescope (OLT) of Hamburg Observatory and the 2.2m telescope at Calar Alto Observatory using BUSCA (Bonn University Simultaneous CAmera). Both the new OLT data, taken with the same instrumental setup as our data taken in 2008, as well as the simultaneously recorded multicolor BUSCA data confirm the low inclination values reported previously, and in fact suggest that the TrES-2b exoplanet has already passed the first inclination threshold (i_min,1 = 83.417) and is not eclipsing the full stellar surface any longer. Using the multi-band BUSCA data we demonstrate that the multicolor light curves can be consistently fitted with a given set of limb darkening coefficients without the need to adjust these coefficients, and further, we can demonstrate that wavelength dependent stellar radius changes must be small as expected from theory. Our new observations provide further evidence for a change of the orbit inclination of the transiting extrasolar planet TrES-2b reported previously. We examine in detail possible causes for this inclination change and argue that the observed change should be interpreted as nodal regression. While the assumption of an oblate host star requires an unreasonably large second harmonic coefficient, the existence of a third body in the form of an additional planet would provide a very natural explanation for the observed secular orbit change. Given the lack of clearly observed short-term variations of transit timing and our observed secular nodal regression rate, we predict a period between approximately 50 and 100 days for a putative perturbing planet of Jovian mass. Such an object should be detectable with present-day radial velocity (RV) techniques.

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Lazarus on 23rd December 2009, 7:07 am

Have to wonder how compatible such a proposed extra planet is with the current radial velocity measurements. As far as I can the available RVs do not have very good time coverage, but even so there should be some constraints there.
avatar
Lazarus
dG star
dG star

Number of posts : 2873
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Sirius_Alpha on 29th June 2010, 8:12 pm

Kepler rules out transit timing variations.

Analysis of Kepler's short-cadence photometry for TrES-2b
http://arxiv.org/abs/1006.5680

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

Post by Sirius_Alpha on 6th May 2012, 8:15 pm

A consistent analysis of three years of ground- and space-based photometry of TrES-2
http://arxiv.org/abs/1205.0969

The G0V dwarf TrES-2A, which is transited by a hot Jupiter, is one of the main short-cadence targets of the Kepler telescope and, therefore, among the photometrically best-studied planetary systems known today. Given the near-grazing geometry of the planetary orbit, TrES-2 offers an outstanding opportunity to search for changes in its orbital geometry. Our study focuses on the secular change in orbital inclination reported in previous studies. We present a joint analysis of the first four quarters of Kepler photometry together with the publicly available ground-based data obtained since the discovery of TrES-2b in 2006. We use a common approach based on the latest information regarding the visual companion of TrES-2A and stellar limb darkening to further refine the orbital parameters. We find that the Kepler observations rule out a secular inclination change of previously claimed order as well as variations of the transit timing, however, they also show slight indication for further variability in the inclination which remains marginally significant.

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

Number of posts : 3515
Location : Earth
Registration date : 2008-04-06

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

Back to top Go down

Re: Transit timing variations at TrES-2?

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