![]() ![]() A satellite in the L2 Lagrange point, such as PLATO (Rauer & Catala 2011), is similar in that respect. 2005) since it bears no relation to the stellar spin axis, which one may assess independently.Įarth-bound observers travel significant distances yearly as they orbit the Sun. This measurement is different from the spectroscopic Rossiter-McLaughlin effect (e.g., Ohta et al. 1), then the effective separation between the two observers, as seen projected on the planet’s orbit, is only b 2cos( l), so (2)One finds that by dividing D observe by D expect one can measure cos( l), and this effect will be seen best for long-period planets (if their period is known precisely enough) and for host stars with higher parallactic angle. ![]() If one adds the possibility that the planet’s orbit may be tilted at an angle l relative to the line separating the two observers (right panel of Fig. This delay is not related, and is actually perpendicular, to the light-time delay between the observers that is caused by different observer positions along the line of sight. We note that higher order effects of finite ecentricity, such as orbital precession, are not currently included in the analysis. | Δ V |/ V ≃ e), where the change can be either positive or negative, relative to the circular case, depending on the argument of periastron ω. Low but nonzero eccentricity e would change V by a fractional amount close to e (i.e. Important is that one expects that the planet will be seen by the different observers at the same transit phase (e.g., first contact is shown here) at a slight delay, also known as parallactic delay, of D expect = b 1/ V where V is the planet’s orbital velocity V = 2 π d 1/ P (for circular orbits, where P is the planet’s orbital period), and b 1 = b 2 d 1/ d 2, or (1)This can also be read simply as the planetary period times the parallax angle subtended by the two observers from the host star. 1: the orbital distance during transit d 1, the distance to the system d 2, the baseline distance between the two observers b 2 and the corresponding distance projected on the planet’s orbit b 1. We begin by defining all the distances given in the left hand panel of Fig. We wish to use the above observational configuration to put such constraints on each transiting member of the system, and if there are more than one, on their sky coplanarity. While the existence of transits practically ensures that the inclination angle i is close to 90°, the sky orientation of the systems remains unconstrained. 2010) and an Earth-bound observer in mind, so the observers are separated by AU-scale distances. We then assume that a particular transit event on that system was observed from two remote locations simultaneously, and the following was developed with Kepler spacecraft (Borucki et al. These components can be either eclipsing stars or transiting exoplanets, but in the text below we use only transiting exoplanets as a specific example, since similar effects for eclipsing binaries are even stronger. We consider a system of one or several eclipsing bodies. Key words: techniques: photometric / planetary systems We specify some initial science questions that this new observable may be able to address. We find that there is a good match between projected capabilities of the future space missions PLATO and CHEOPS and the new observable. We show that a new observable from transit photometry becomes available when very high-precision transit timing is available. We also find that the sky coplanarity of multiple objects in the same system can be probed more easily than the sky position angle of each of the objects separately.Ĭonclusions. We also compute the theoretical timing precision for the PLATO mission, which will observe a similar stellar population and find that a 1 s effect will frequently be easily observable. Our calculation of the magnitude of the effect for all currently known planets (should they exhibit transits) find that almost 200 of them – mostly radial-velocity detected planets – have predicted timing effects greater than 1 s. A simple geometrical argument allows us to show that the apparent timing difference also depends on the sky position angle of the planetary (or secondary) orbit, relative to the ecliptic plane. We compare the apparent difference in timing of transiting planets (or eclipsing binaries) that are observed from widely separated locations (parallactic delay). Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, GermanyĪims. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes ![]()
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