Posts Tagged planetary data

Recent Postings from planetary data

EXOFAST: A fast exoplanetary fitting suite in IDL

We present EXOFAST, a fast, robust suite of routines written in IDL which is designed to fit exoplanetary transits and radial velocity variations simultaneously or separately, and characterize the parameter uncertainties and covariances with a Differential Evolution Markov Chain Monte Carlo method. We describe how our code self-consistently incorporates both data sets to simultaneously derive stellar parameters along with the transit and RV parameters, resulting in consistent, but tighter constraints on an example fit of the discovery data of HAT-P-3b that is well-mixed in under two minutes on a standard desktop computer. We describe in detail how our code works and outline ways in which the code can be extended to include additional effects or generalized for the characterization of other data sets — including non-planetary data sets. We discuss the pros and cons of several common ways to parameterize eccentricity, highlight a subtle mistake in the implementation of MCMC that would bias the inferred eccentricity of intrinsically circular orbits to significantly non-zero results, discuss a problem with IDL’s built-in random number generator in its application to large MCMC fits, and derive a method to analytically fit the linear and quadratic limb darkening coefficients of a planetary transit. Finally, we explain how we achieved improved accuracy and over a factor of 100 improvement in the execution time of the transit model calculation. Our entire source code, along with an easy-to-use online interface for several basic features of our transit and radial velocity fitting, are available online at http://astroutils.astronomy.ohio-state.edu/exofast.

EXOFAST: A fast exoplanetary fitting suite in IDL [Replacement]

We present EXOFAST, a fast, robust suite of routines written in IDL which is designed to fit exoplanetary transits and radial velocity variations simultaneously or separately, and characterize the parameter uncertainties and covariances with a Differential Evolution Markov Chain Monte Carlo method. We describe how our code self-consistently incorporates both data sets to simultaneously derive stellar parameters along with the transit and RV parameters, resulting in consistent, but tighter constraints on an example fit of the discovery data of HAT-P-3b that is well-mixed in under two minutes on a standard desktop computer. We describe in detail how our code works and outline ways in which the code can be extended to include additional effects or generalized for the characterization of other data sets — including non-planetary data sets. We discuss the pros and cons of several common ways to parameterize eccentricity, highlight a subtle mistake in the implementation of MCMC that would bias the inferred eccentricity of intrinsically circular orbits to significantly non-zero results, discuss a problem with IDL’s built-in random number generator in its application to large MCMC fits, and derive a method to analytically fit the linear and quadratic limb darkening coefficients of a planetary transit. Finally, we explain how we achieved improved accuracy and over a factor of 100 improvement in the execution time of the transit model calculation. Our entire source code, along with an easy-to-use online interface for several basic features of our transit and radial velocity fitting, are available online at http://astroutils.astronomy.ohio-state.edu/exofast .

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Cross-Listing]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession. It was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precession caused by a small mismodeling in the quadrupole mass moment of the Sun, actually modeled, of the order of (0.1-0.2) x 10^-7. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Replacement]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession. The supplementary precession was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precession caused by a small mismodeling in the quadrupole mass moment of the Sun, actually modeled in INPOP10a, of the order of (0.1-0.2) x 10^-7. On the contrary, the oblateness of Mercury itself has a negligible impact on its perihelion. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Replacement]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession. The supplementary precession was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precession caused by a small mismodeling in the quadrupole mass moment of the Sun, actually modeled in INPOP10a, of the order of (0.1-0.2) x 10^-7. On the contrary, the oblateness of Mercury itself has a negligible impact on its perihelion. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Replacement]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession. The supplementary precession was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precession caused by a small mismodeling in the quadrupole mass moment of the Sun, actually modeled in INPOP10a, of the order of (0.1-0.2) x 10^-7. On the contrary, the oblateness of Mercury itself has a negligible impact on its perihelion. The same holds for the mismodelled actions of both the largest individual asteroids and the ring of the minor asteroids. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Replacement]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession, provided that the latter is to be entirely attributed to frame-dragging. The supplementary precession was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precessions caused by small mismodeling in the quadrupole mass moment of the Sun and in the PPN parameter beta entering the Schwarzschild-like 1PN precession, both modeled in INPOP10a. On the contrary, the oblateness of Mercury itself has a negligible impact on its perihelion. The same holds for the mismodelled actions of both the largest individual asteroids and the ring of the minor asteroids. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Mercury and frame-dragging in light of the MESSENGER flybys: conflict with general relativity, poor knowledge of the physical properties of the Sun, data reduction artifact, or still insufficient observations? [Replacement]

The Lense-Thirring precession of the longitude of perihelion of Mercury, as predicted by general relativity by using the value of the Sun’s angular momentum S = 190 x 10^39 kg m^2 s^-1 from helioseismology, is -2.0 milliarcseconds per century, computed in a celestial equatorial reference frame. It disagrees at 4-{\sigma} level with the correction 0.4 +/- 0.6 milliarcseconds per century to the standard Newtonian/Einsteinian precession, provided that the latter is to be entirely attributed to frame-dragging. The supplementary precession was recently determined in a global fit with the INPOP10a ephemerides to a long planetary data record (1914-2010) including also 3 data points collected in 2008-2009 from the MESSENGER spacecraft. The INPOP10a models did not include the solar gravitomagnetic field at all, so that its signature might have partly been removed in the data reduction process. On the other hand, the Lense-Thirring precession may have been canceled to a certain extent by the competing precessions caused by small mismodeling in the quadrupole mass moment of the Sun and in the PPN parameter beta entering the Schwarzschild-like 1PN precession, both modeled in INPOP10a. On the contrary, the oblateness of Mercury itself has a negligible impact on its perihelion. The same holds for the mismodelled actions of both the largest individual asteroids and the ring of the minor asteroids. Future analysis of more observations from the currently ongoing MESSENGER mission will shed further light on such an issue which, if confirmed, might potentially challenge our present-day picture of the currently accepted laws of gravitation and/or of the physical properties of the Sun.

Constraints on the location of a putative distant massive body in the Solar System from recent planetary data [Replacement]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a very distant, pointlike massive object X. Apart from the semi-major axis a, all the other Keplerian osculating orbital elements experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d_X at which X may exist by comparing our prediction of the long-term variation of the longitude of the perihelion \varpi to the latest empirical determinations of the corrections \Delta\dot\varpi to the standard Newtonian/Einsteinian secular precessions of several solar system planets recently estimated by independent teams of astronomers. We obtain the following approximate lower bounds on dX for the assumed masses of X quoted in brackets: 150 – 200 au (m_Mars), 250 – 450 au (0.7 m_Earth), 3500 – 4500 au (4 m_Jup).

Constraints on the location of a putative distant massive body in the Solar System from recent planetary data [Replacement]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a very distant, pointlike massive object X. Apart from the semi-major axis a, all the other Keplerian osculating orbital elements experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d_X at which X may exist by comparing our prediction of the long-term variation of the longitude of the perihelion \varpi to the latest empirical determinations of the corrections \Delta\dot\varpi to the standard Newtonian/Einsteinian secular precessions of several solar system planets recently estimated by independent teams of astronomers. We obtain the following approximate lower bounds on dX for the assumed masses of X quoted in brackets: 150 – 200 au (m_Mars), 250 – 450 au (0.7 m_Earth), 3500 – 4500 au (4 m_Jup).

Constraints on the location of a putative distant massive body in the Solar System and on the External Field Effect of MOND from recent planetary data [Cross-Listing]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a distant, pointlike massive object X (Planet X/Nemesis/Tyche). It turns out that, apart from the semimajor axis $a$, all the other Keplerian orbital elements of the perturbed planet experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. A numerical integration of the equations of motion of the perturbed planet yielding the temporal evolution of all its orbital elements successfully confirms our analytical results. We infer constraints on the minimum distance $d_{\rm X}$ at which the putative body X can exist by comparing, first, our prediction of the long-term variation of the longitude of the perihelion $\varpi$ to the latest empirical determinations of the corrections $\Delta\dot\varpi$ to the standard Newtonian/Einsteinian secular precessions of several planets of the solar system recently obtained. Independent teams of astronomers estimated them by fitting accurate dynamical force models$-$not including the action of X itself$-$to observational data records covering almost one century. Then, we numerically compute the perturbations induced by X on the range $\rho$, the right ascension $\alpha$ and the declination $\delta$ of Saturn. We compare them with the latest residuals produced by analyzing records of radiotechnical data from the Cassini spacecraft spanning some years. Tighter constraints on $d_{\rm X}$ are, thus, obtained. The combined use of all the methods adopted yield the following lower bounds on $d_{\rm X}$ for the assumed masses of X quoted in brackets: $141-281$ au (Mars), $300-600$ au (Earth), $771-1542$ au (Neptune), $2037-4074$ au (Jupiter), $8784-17568$ au (brown dwarf with $m_{\rm X}=80\ m_{\rm Jup}$), $16434-32868$ au (red dwarf with $m_{\rm X}=0.5\ {\rm M}_{\oplus}$), $20709-41418$ au (Sun). Alternative strategies which could be followed are pointed out. Constraints on the adimensional parameter $-q$ of the External Field Effect within the MOdified Newtonian Dynamics are obtained from the range residuals of Saturn: it turns out $-q\approx 0.01-0.04$ (at $1/3-\sigma$ level of rejection).

Constraints on the location of a putative distant massive body in the Solar System and on the External Field Effect of MOND from recent planetary data [Replacement]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a distant, pointlike massive object X. Apart from the semimajor axis a, all the other Keplerian orbital elements of the perturbed planet experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d_X at which the putative body X can exist by comparing, first, our prediction of the long-term variation of the longitude of the perihelion \varpi to the latest empirical determinations of the corrections \Delta\dot\varpi to the standard Newtonian/Einsteinian secular precessions of several planets of the solar system recently obtained. Independent teams of astronomers estimated them by fitting accurate dynamical force models$-$not including the action of X itself$-$to observational data records covering almost one century. Then, we numerically compute the perturbations induced by X on the range \rho, the right ascension \alpha and the declination \delta of Saturn. We compare them with the latest residuals produced by analyzing records of radiotechnical data from the Cassini spacecraft spanning some years. Tighter constraints on d_X are, thus, obtained. The combined use of all the methods adopted yield the following lower bounds on d_X for the assumed masses of X quoted in brackets: 141-281 au (Mars), 300-600 au (Earth), 771-1542 au (Neptune), 2037-4074 au (Jupiter), 8784-17568 au (brown dwarf with m_X = 80 m_Jup), 16434-32868 au (red dwarf with m_X = 0.5 M_Sun), 20709-41418 au (Sun). Alternative strategies which could be followed are pointed out. Constraints on the adimensional parameter -q of the External Field Effect within the MOdified Newtonian Dynamics are obtained from the range residuals of Saturn: it turns out -q\approx 0.01-0.04 (at 1/3-\sigma level of rejection).

Constraints on the location of a putative distant massive body in the Solar System and on the External Field Effect of MOND from recent planetary data [Replacement]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a distant, pointlike massive object X. Apart from the semimajor axis a, all the other Keplerian orbital elements of the perturbed planet experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d_X at which the putative body X can exist by comparing, first, our prediction of the long-term variation of the longitude of the perihelion \varpi to the latest empirical determinations of the corrections \Delta\dot\varpi to the standard Newtonian/Einsteinian secular precessions of several planets of the solar system recently obtained. Independent teams of astronomers estimated them by fitting accurate dynamical force models$-$not including the action of X itself$-$to observational data records covering almost one century. Then, we numerically compute the perturbations induced by X on the range \rho, the right ascension \alpha and the declination \delta of Saturn. We compare them with the latest residuals produced by analyzing records of radiotechnical data from the Cassini spacecraft spanning some years. Tighter constraints on d_X are, thus, obtained. The combined use of all the methods adopted yield the following lower bounds on d_X for the assumed masses of X quoted in brackets: 141-281 au (Mars), 300-600 au (Earth), 771-1542 au (Neptune), 2037-4074 au (Jupiter), 8784-17568 au (brown dwarf with m_X = 80 m_Jup), 16434-32868 au (red dwarf with m_X = 0.5 M_Sun), 20709-41418 au (Sun). Alternative strategies which could be followed are pointed out. Constraints on the adimensional parameter -q of the External Field Effect within the MOdified Newtonian Dynamics are obtained from the range residuals of Saturn: it turns out -q\approx 0.01-0.04 (at 1/3-\sigma level of rejection).

Constraints on the location of a putative distant massive body in the Solar System from recent planetary data [Replacement]

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a very distant, pointlike massive object X. Apart from the semi-major axis a, all the other Keplerian osculating orbital elements experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d_X at which X may exist by comparing our prediction of the long-term variation of the longitude of the perihelion \varpi to the latest empirical determinations of the corrections \Delta\dot\varpi to the standard Newtonian/Einsteinian secular precessions of several solar system planets recently estimated by independent teams of astronomers. We obtain the following approximate lower bounds on dX for the assumed masses of X quoted in brackets: 150 – 200 au (m_Mars), 250 – 450 au (0.7 m_Earth), 3500 – 4500 au (4 m_Jup).

A preliminary XML-based search system for planetary data

Planetary sciences can benefit from several different sources of information, i.e. ground-based or near Earth-based observations, space missions and laboratory experiments. The data collected from these sources, however, are spread over a number of smaller, separate communities and stored through different facilities: this makes it difficult to integrate them. The IDIS initiative, born in the context of the Europlanet project, performed a pilot study of the viability and the issues to be overcome in order to create an integrated search system for planetary data. As part of the results of such pilot study, the IDIS Small Bodies and Dust node developed a search system based on a preliminary XML data model. Here we introduce the goals of the IDIS initiative and describe the structure and the working of this search system. The source code of the search system is released under GPL license to allow people interested in participating to the IDIS initiative both as developers and as data providers to familiarise with the search environment and to allow the creation of volunteer nodes to be integrated into the existing network.

The LAEX and NASA portals for CoRoT public data

* Aims. We describe here the main functionalities of the LAEX (Laboratorio de Astrofisica Estelar y Exoplanetas/Laboratory for Stellar Astrophysics and Exoplanets) and NASA portals for CoRoT Public Data. The CoRoT archive at LAEX was opened to the community in January 2009 and is managed in the framework of the Spanish Virtual Observatory. NStED (NASA Star and Exoplanet Database) serves as the CoRoT portal for the US astronomical community. NStED is a general purpose stellar and exoplanet archive with the aim of providing support for NASA planet finding and characterisation goals, and the planning and support of NASA and other space missions. CoRoT data at LAEX and NStED can be accessed at http://sdc.laeff.inta.es/corotfa/ and http://nsted.ipac.caltech.edu,respectively. * Methods. Based on considerable experience with astronomical archives, the aforementioned archives are designed with the aim of delivering science-quality data in a simple and efficient way. * Results. LAEX and NStED not only provide access to CoRoT Public Data but furthermore serve a variety of observed and calculated astrophysical data. In particular, NStED provides scientifically validated information on stellar and planetary data related to the search for and characterization of extrasolar planets, and LAEX makes any information from Virtual Observatory services available to the astronomical community.

Binarity of Transit Host Stars - Implications on Planetary Parameters

Straight-forward derivation of planetary parameters can only be achieved in transiting planetary systems. However, planetary attributes such as radius and mass strongly depend on stellar host parameters. Discovering a transit host star to be multiple leads to a necessary revision of the derived stellar and planetary parameters. Based on our observations of 14 transiting exoplanet hosts, we derive parameters of the individual components of three transit host stars (WASP-2, TrES-2, and TrES-4) which we detected to be binaries. Two of these have not been known to be multiple before. Parameters of the corresponding exoplanets are revised. High-resolution "Lucky Imaging" with AstraLux at the 2.2m Calar Alto telescope provided near diffraction limited images in i’ and z’ passbands. These results have been combined with existing planetary data in order to recalibrate planetary attributes. Despite the faintness (delta mag ~ 4) of the discovered stellar companions to TrES-2, TrES-4, and WASP-2, light-curve deduced parameters change by up to more than 1sigma. We discuss a possible relation between binary separation and planetary properties, which – if confirmed – could hint at the influence of binarity on the planet formation process.

 

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