The Potential of the Timing Method to Detect Evolved Planetary Systems

Silvotti, R.; Szabo, Robert M.; Degroote, P.; Østensen, R. H.; Schuh, S.

doi:10.1063/1.3570966

Cited by 3 publications

(4 citation statements)

References 32 publications

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“…It is therefore possible to register very small differences in the arrival times of the mid-egress photons at various wavelengths, allowing the detection of extremely low-mass circumbinary objects through the analysis of the observed-calculated O-C diagram ("O" refers to the Observed times of the eclipse egress, while "C" to those Computed with a linear ephemeris). This method is similar to the radio approach used to detect planets around pulsars (e.g., Backer et al 1993), and has been used to find giant planets orbiting the other eclipsing polar DP Leo (Qian et al 2010;Beuermann et al 2011a), the extreme horizontal branch pulsating star V391 Peg (Silvotti et al 2007), and the others listed by Silvotti et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Detection of a planetary system orbiting the eclipsing polar HU Aqr

Qian

Liu

Liao

et al. 2011

Monthly Notices of the Royal Astronomical Society: Letters

118

175

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Using the precise times of mid-egress of the eclipsing polar HU Aqr, we discovered that this polar is orbited by two or more giant planets. The two planets detected so far have masses of at least 5.9 and 4.5\,M_{Jup}. Their respective distances from the polar are 3.6 AU and 5.4 AU with periods of 6.54 and 11.96 years, respectively. The observed rate of period decrease derived from the downward parabolic change in O-C curve is a factor 15 larger than the value expected for gravitational radiation. This indicates that it may be only a part of a long-period cyclic variation, revealing the presence of one more planet. It is interesting to note that the two detected circumbinary planets follow the Titus-Bode law of solar planets with n=5 and 6. We estimate that another 10 years of observations will reveal the presence of the predicted third planet.Comment: 13 pages, 4 figures, 2 table

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Section: Introductionmentioning

confidence: 99%

Detection of a planetary system orbiting the eclipsing polar HU Aqr

Qian

Liu

Liao

et al. 2011

Monthly Notices of the Royal Astronomical Society: Letters

118

175

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“…Recently, the high photometric accuracy achievable from space, in particular with the Kepler mission, has led to a renewed interest in this technique (Silvotti et al 2011), and two systematic approaches based on frequency modulation (FM) and phase modulation (PM, equivalent to the O-C method) were proposed (Shibahashi & Kurtz 2012;Telting et al 2012;Shibahashi et al 2015;Murphy et al 2014Murphy et al , 2016b.…”

Section: Introductionmentioning

confidence: 99%

The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data

Silvotti

Schuh

Kim

et al. 2018

A&A

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V391 Peg (alias HS 2201+2610) is a subdwarf B (sdB) pulsating star that shows both p-and g-modes. By studying the arrival times of the p-mode maxima and minima through the O-C method, in a previous article the presence of a planet was inferred with an orbital period of 3.2 years and a minimum mass of 3.2 M Jup . Here we present an updated O-C analysis using a larger data set of 1066 h of photometric time series (∼2.5× larger in terms of the number of data points), which covers the period between 1999 and 2012 (compared with 1999-2006 of the previous analysis). Up to the end of 2008, the new O-C diagram of the main pulsation frequency ( f 1 ) is compatible with (and improves) the previous two-component solution representing the long-term variation of the pulsation period (parabolic component) and the giant planet (sine wave component). Since 2009, the O-C trend of f 1 changes, and the time derivative of the pulsation period (ṗ) passes from positive to negative; the reason of this change of regime is not clear and could be related to nonlinear interactions between different pulsation modes. With the new data, the O-C diagram of the secondary pulsation frequency ( f 2 ) continues to show two components (parabola and sine wave), like in the previous analysis. Various solutions are proposed to fit the O-C diagrams of f 1 and f 2 , but in all of them, the sinusoidal components of f 1 and f 2 differ or at least agree less well than before. The nice agreement found previously was a coincidence due to various small effects that are carefully analyzed. Now, with a larger dataset, the presence of a planet is more uncertain and would require confirmation with an independent method. The new data allow us to improve the measurement ofṗ for f 1 and f 2 : using only the data up to the end of 2008, we obtainṗ 1 = (1.34 ± 0.04) × 10 −12 anḋ p 2 = (1.62 ± 0.22) × 10 −12 . The long-term variation of the two main pulsation periods (and the change of sign ofṗ 1 ) is visible also in direct measurements made over several years. The absence of peaks near f 1 in the Fourier transform and the secondary peak close to f 2 confirm a previous identification as l = 0 and l = 1, respectively, and suggest a stellar rotation period of about 40 days. The new data allow constraining the main g-mode pulsation periods of the star.

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“…To complete this chapter I want to refer the reader to Silvotti et al (2011), who study the potential of data taken by the CoRoT and Kepler space missions in the context of a timing analysis. The authors also test the applicability of pulsation timing to δ Scuti, β Cephei and RR Lyrae stars.…”

Section: Sensitivity Of the Timing Methodsmentioning

confidence: 99%

“…In their Table 1, Silvotti et al (2011) list the currently known post-RGB exoplanetary systems (with the addition of brown dwarf companions to complete the picture of substellar companions). A controversial discussion whether or not the sdB HD 149382 has a substellar companion can be found in Geier et al (2009a) and Jacobs et al (2011).…”

Section: Planetary Systems Around Evolved Starsmentioning

confidence: 99%

The search for substellar companions to subdwarf B stars in connection with evolutionary aspects

Lutz¹

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The formation and evolution of hot subluminous B stars (sdB stars in the following) is not entirely understood. Although the current evolutionary status, i. e. the position in the Hertzsprung-Russell diagram, can be characterized and interpreted quite well, the preceding evolution of these objects remains uncertain. Since sdB stars do not follow a standard evolution of low mass stars, there must have been some event or phase in their history which led to a departure of the standard description. It is well-established in the literature that this event is connected to an enhanced mass loss of the sdB progenitor star during its red giant phase. This enhanced mass loss is a prerequisite to explain the very existence of sdB stars, its cause is, however, matter of debate. In the case of subdwarf B stars in binary systems, formation scenarios invoking Roche-lobe overflow and common envelope evolution are most promising. Theory and observations agree quite well in this case. However, there are some issues concerning single sdB stars, i. e. such stars which are not part of a binary system and therefore do not have a stellar companion. Such single sdB stars are an integral part of this thesis. One particular hypothesis discussed in the literature predicts that even substellar companions like brown dwarfs or exoplanets may be able to have a decisive influence on the formation of single sdB stars. A major goal of this present thesis is to investigate this hypothesis by searching for substellar companions to subdwarf B stars. Another goal is to pin down the evolutionary status of the investigated sdB stars and to directly measure their evolutionary timescales. The precise purposes are hence the search for substellar companions and the determination of evolutionary timescales. To achieve the goals mentioned above, the so-called EXOTIME program has been set up. EXOTIME conducts a long-term monitoring of five pulsating sdB stars with means of ground based time-resolved relative photometry. xi I will motivate the basic questions and intentions which led to the idea of setting up this thesis and to investigate the subdwarf B stars with respect to substellar companions. Chapter three is intended to introduce the purpose and goals of the EXOTIME project and to briefly characterize the target stars central to this thesis. Subsequently, in chapter four I will present the data archive built up during the last years, with a special emphasis on the observation facilities and observational strategy. Chapter five provides a description of the methods being applied to investigate the subdwarf B stars for substellar companions. A focus is set on the O-C timing method and a comparison to various other exoplanet detection methods. The results of the analysis are extensively presented in chapter six. Chapter seven will discuss these results, put them into a broader context and address various other implications and applications. A summary and outlook, as provided in chapter eight, will conclude this thesis. xiv -Miles Kington Welcome to Kington...

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The Potential of the Timing Method to Detect Evolved Planetary Systems

Cited by 3 publications

References 32 publications

Detection of a planetary system orbiting the eclipsing polar HU Aqr

Detection of a planetary system orbiting the eclipsing polar HU Aqr

The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data

The search for substellar companions to subdwarf B stars in connection with evolutionary aspects

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