Numerical predictions for planets in the debris discs of ...
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Resolved debris disc images can exhibit a range of radial and azimuthal structures (gaps, Resolved debris disc images can exhibit a range of radial and azimuthal structures (gaps, rings and warps) resulting from planetary companions shaping the disc*. rings and warps) resulting from planetary companions shaping the disc*. Recent work by Rodigas et al. (2014) present a framework by which one can estimate the Recent work by Rodigas et al. (2014) present a framework by which one can estimate the maximum mass and minimum semi major axis of a planet from the debris disc wi maximum mass and minimum semi major axis of a planet from the debris disc width in scattered light. We use the predictions of Rodigas et al. applied to HD 202628 and HD 207129 and numerically search for a better estimate of the potential companion parameters. *: We note that asymmetries in the disc can also result from non planet interaction (Lyra & Kuchner, 2013). Both discs surround solar type stars between 1-3 Gyr old at 24 and 16 parsecs, and were observed by Krist et al. (2010, 2012) – see Figure 1. No planets detection have been yet detected around either sources. The main stellar and disc parameters of HD 202628 and HD 207129 are summarized in Table 1. Table 1: Properties for HD 202628 from Krist et al. (2012) and for HD 207129 from Krist et al. (2010). Figure 1: Scattered light observations of HD 202628 (bottom), and HD 207129 (top) by Krist et al. (2010, 2012) We started with planetary initial conditions predicted by Rodigas et al. (2014) and disc initial conditions taken directly from scattered light observations. We perform simulations using our own modified version of the N-body code SWIFT (Levison & Duncan, 1994) which includes radiation forces (radiation pressure, stellar wind and Poynting-Robertson drag) for a duration t=10 t coll . We then create synthetics scattered-light images from our simulations and compare it to the observations. If no satisfactory match is found, we repeat the process and cover a broader range of planetary input parameters. See Figure 2 for a schematic description. A total of 12 simulations were run and all the best-fit matching features are the disc location and width, eccentricity and offset. Figure 2: Description of the numerical method. The best fit images are presented in Figure 3. The best fit parameters are given in Table 2. HD 202628 : The initial planetary orbit predictions led to a disc structure more weakly perturbed compared to observations. However, an excellent match was found for a planetary semi-major axis located at a distance of about 30 AU from the minimal value derived by Rodigas et al. HD207129: The initial planetary orbit predictions led to a disc structure more strongly perturbed compared to observations. We found a satisfactory match using half of the maximal eccentricity estimated by Rodigas et al. We conclude that the predictions of Rodigas et al. (2014) are a serious baseline for estimating the orbit of a potential planetary companion, but should be completed by numerical checkings. (a) : HD 207129 (b) : HD202628 Figure 3 : Comparison between scattered light observations (left) and our best matching numerical simulation (right) for HD 207129 and HD202628. Table 2: Best fit for the planet and disc parameters and comparison with the observations and predictions for HD 207129 and HD 202628. In our simulations, the resulting structure of the discs was found to be independent of the planetary mass suggesting that secular perturbations are at work in HD 202628 and HD 207129 (Wyatt et al. , 1999) As the collisional lifetime of grains in those discs are a factor 140 shorter then the PR drag time scale, destructive collisions can prevent planet induced structures in the disc from forming (Stark & Kuchner, 2009). We ran test simulations for HD 207129 using 3 different integration time (t = t coll , 10t coll , 100t coll ). The 3 simulations resulted in similar disc offsets and widths, however we note that (i) the final disc eccentricity with t= t coll resulted in higher values and (ii), grains in the disc stayed confined in their initial parent body belt and do not undergo any major changes in their orbits, suggesting that the simulations were not run long enough. Table 3: Resulting disc structure for simulations with different integration time. In conclusion, we stress that while collisions are indeed the dominant factor of the dust lifetime, running simulations for t=t coll can affect simulations results in two important ways: (i) no disc shaping by secular perturbations of the planet yet known to affect the disc, (ii) a remaining dependence of initial condition for the particles evolution. Bibliography: Koerner, D. W., Kim, S., Trilling, D. E., et al. 2010, ApJL, 710, L26 Krist, J. E., Stapelfeldt, K. R., Bryden, G., & Plavchan, P. 2012, AJ, 144, 45 Krist, J. E., Stapelfeldt, K. R., Bryden, G., et al. 2010, AJ, 140, 1051 Levison, H. F., & Duncan, M. J. 1994, Icarus, 108, 18 Lyra, W., & Kuchner, M. 2013, Nature, 499, 184 Perryman,M. A. C., Lindegren, L., Kovalevsky, J., et al. 1997, A&A, 323, L49 Rodigas, T. J., Malhotra, R., & Hinz, P. M. 2014, ApJ,780, 65 Stark, C. C., & Kuchner, M. J. 2009, ApJ, 707, 543 Elodie Thilliez Elodie Thilliez PhD Student at SWINBURNE UNIVERSITY PhD Student at SWINBURNE UNIVERSITY Mail: [email protected] Mail: [email protected] Supervisor: Prof Sarah Maddison Supervisor: Prof Sarah Maddison Numerical predictions for planets in the debris Numerical predictions for planets in the debris discs of HD 202628 and HD 207129 discs of HD 202628 and HD 207129 E. Thilliez & S. Maddison E. Thilliez & S. Maddison
Transcript of Numerical predictions for planets in the debris discs of ...
Resolved debris disc images can exhibit a range of radial and azimuthal structures (gaps, Resolved debris disc images can exhibit a range of radial and azimuthal structures (gaps, rings and warps) resulting from planetary companions shaping the disc*. rings and warps) resulting from planetary companions shaping the disc*. Recent work by Rodigas et al. (2014) present a framework by which one can estimate the Recent work by Rodigas et al. (2014) present a framework by which one can estimate the maximum mass and minimum semi major axis of a planet from the debris disc wimaximum mass and minimum semi major axis of a planet from the debris disc width in scattered light. We use the predictions of Rodigas et al. applied to HD 202628 and HD 207129 and numerically search for a better estimate of the potential companion parameters.
*: We note that asymmetries in the disc can also result from non planet interaction (Lyra & Kuchner, 2013).
Both discs surround solar type stars between 1-3 Gyr old at 24 and 16 parsecs, and were observed by Krist et al. (2010, 2012) – see Figure 1. No planets detection have been yet detected around either sources. The main stellar and disc parameters of HD 202628 and HD 207129 are summarized in Table 1.
Table 1: Properties for HD 202628 from Krist et al. (2012) and for HD 207129 from Krist et al. (2010).
Figure 1: Scattered light observations of HD 202628 (bottom), and HD 207129 (top) by Krist et al. (2010, 2012)
We started with planetary initial conditions predicted by Rodigas et al. (2014) and disc initial conditions taken directly from scattered light observations. We perform simulations using our own modified version of the N-body code SWIFT (Levison & Duncan, 1994) which includes radiation forces (radiation pressure, stellar wind and Poynting-Robertson drag) for a duration t=10 tcoll. We then create synthetics scattered-light images from our simulations and compare it to the observations. If no satisfactory match is found, we repeat the process and cover a broader range of planetary input parameters. See Figure 2 for a schematic description. A total of 12 simulations were run and all the best-fit matching features are the disc location and width, eccentricity and offset.
Figure 2: Description of the numerical method.
The best fit images are presented in Figure 3. The best fit parameters are given in Table 2. HD 202628 : The initial planetary orbit predictions led to a disc structure more weakly perturbed compared to observations. However, an excellent match was found for a planetary semi-major axis located at a distance of about 30 AU from the minimal value derived by Rodigas et al.
HD207129: The initial planetary orbit predictions led to a disc structure more strongly perturbed compared to observations. We found a satisfactory match using half of the maximal eccentricity estimated by Rodigas et al.
We conclude that the predictions of Rodigas et al. (2014) are a serious baseline for estimating the orbit of a potential planetary companion, but should be completed by numerical checkings.
(a) : HD 207129 (b) : HD202628Figure 3: Comparison between scattered light observations (left) and our best
matching numerical simulation (right) for HD 207129 and HD202628.
Table 2: Best fit for the planet and disc parameters and comparison with the observations and predictions for HD 207129 and
HD 202628.In our simulations, the resulting structure of the discs was found to be independent of the planetary mass suggesting that secular perturbations are at work in HD 202628 and HD 207129 (Wyatt et al. , 1999)
As the collisional lifetime of grains in those discs are a factor 140 shorter then the PR drag time scale, destructive collisions can prevent planet induced structures in the disc from forming (Stark & Kuchner, 2009). We ran test simulations for HD 207129 using 3 different integration time (t = t
coll, 10t
coll, 100t
coll ). The
3 simulations resulted in similar disc offsets and widths, however we note that (i) the final disc eccentricity with t= t
coll resulted in higher values and (ii), grains in the disc stayed confined in their initial parent body
belt and do not undergo any major changes in their orbits, suggesting that the simulations were not run long enough.
Table 3: Resulting disc structure for simulations with different integration time.
In conclusion, we stress that while collisions are indeed the dominant factor of the dust lifetime, running simulations for t=tcoll can affect simulations results in two important ways:
(i) no disc shaping by secular perturbations of the planet yet known to affect the disc, (ii) a remaining dependence of initial condition for the particles evolution.
Bibliography:Koerner, D. W., Kim, S., Trilling, D. E., et al. 2010, ApJL, 710, L26Krist, J. E., Stapelfeldt, K. R., Bryden, G., & Plavchan, P. 2012, AJ, 144, 45Krist, J. E., Stapelfeldt, K. R., Bryden, G., et al. 2010, AJ, 140, 1051Levison, H. F., & Duncan, M. J. 1994, Icarus, 108, 18Lyra, W., & Kuchner, M. 2013, Nature, 499, 184Perryman,M. A. C., Lindegren, L., Kovalevsky, J., et al. 1997, A&A, 323, L49Rodigas, T. J., Malhotra, R., & Hinz, P. M. 2014, ApJ,780, 65Stark, C. C., & Kuchner, M. J. 2009, ApJ, 707, 543
Elodie ThilliezElodie ThilliezPhD Student at SWINBURNE UNIVERSITYPhD Student at SWINBURNE UNIVERSITYMail: [email protected]: [email protected]: Prof Sarah MaddisonSupervisor: Prof Sarah Maddison
Numerical predictions for planets in the debris Numerical predictions for planets in the debris discs of HD 202628 and HD 207129discs of HD 202628 and HD 207129
E. Thilliez & S. MaddisonE. Thilliez & S. Maddison
