1,721,174 research outputs found
Host Star Properties and Transit Exclusion for the HD 38529 Planetary System
Get PDFThe transit signature of exoplanets provides an avenue through which characterization of exoplanetary properties may be undertaken, such as studies of mean density, structure, and atmospheric composition. The Transit Ephemeris Refinement and Monitoring Survey is a program to expand the catalog of transiting planets around bright host stars by refining the orbits of known planets discovered with the radial velocity technique. Here we present results for the HD 38529 system. We determine fundamental properties of the host star through direct interferometric measurements of the radius and through spectroscopic analysis. We provide new radial velocity measurements that are used to improve the Keplerian solution for the two known planets, and we find no evidence for a previously postulated third planet. We also present 12 years of precision robotic photometry of HD 38529 that demonstrate the inner planet does not transit and the host star exhibits cyclic variations in seasonal mean brightness with a timescale of approximately six years
Dust in the HD 38529 planetary system
No full textIn this paper we briefly summarized a study on HD 38529, one of the few (less than a dozen) stars known to date to harbor both planetary companions and IR excess, the later due to debris dust and evidence of the presence of planetesimals. For details, please refer to Moro-MartÃn et al. teyear{ama07b}
The dust, planetesimals, and planets of HD 38529
Get PDFHD 38529 is a post-main-sequence G8 III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having Msini of 0.8 and 12.2 MJup, semimajor axes of 0.13 and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 mum of 4.7, a small excess at 33 mum (S/N=2.6), and no excess <30 mum. We discuss the distribution of the potential dust-producing planetesimals from the study of the dynamical perturbations of the two known planets, considering in particular the effect of secular resonances. We identify three dynamically stable niches at 0.4-0.8, 20-50, and beyond 60 AU. We model the spectral energy distribution (SED) of HD 38529 to find out which of these niches show signs of harboring dust-producing planetesimals. The secular analysis, together with the SED modeling results, suggest that the planetesimals responsible for most of the dust emission are likely located within 20-50 AU, a configuration that resembles that of the Jovian planets + Kuiper Belt in our solar system. Finally, we place upper limits (8×10-6 lunar masses of 10 mum particles) to the amount of dust that could be located in the dynamically stable region that exists between the two planets (0.25-0.75 AU)
Robust asteroseismic properties of the bright planet host HD 38529
Get PDFThe Transiting Exoplanet Survey Satellite (TESS) is recording short-cadence, high duty-cycle timeseries across most of the sky, which presents the opportunity to detect and study oscillations in interesting stars, in particular planet hosts. We have detected and analysed solar-like oscillations in the bright G4 subgiant HD 38529, which hosts an inner, roughly Jupiter-mass planet on a 14.3d orbit and an outer, low-mass brown dwarf on a 2136d orbit. We combine results from multiple stellar modelling teams to produce robust asteroseismic estimates of the star’s properties, including its mass M=1.48±0.04M⊙, radius R=2.68±0.03R⊙, and age t=3.07±0.39Gyr. Our results confirm that HD 38529 has a mass near the higher end of the range that can be found in the literature and also demonstrate that precise stellar properties can be measured given shorter timeseries than produced by CoRoT, Kepler, or K2
A Planetary Companion to HD 40979 and Additional Planets Orbiting HD 12661 and HD 38529
Get PDFWe report the detection of three extrasolar planets from the Lick and Keck observatories. The F8 V star HD 40979 has a companion with orbital period P = 263.1 ± 3 days, eccentricity e = 0.25 ± 0.05, and velocity semiamplitude K = 101.2 ± 5.6 m s-1. The inferred semimajor axis is 0.83 AU and M sin i = 3.28MJup. Observations of planetary companions orbiting the G6 V star HD 12661 and the G4 IV star HD 38529 have already been published, and here we report additional, longer period companions for both of these stars. The outer companion to HD 12661 has Pc = 1444.5 ± 12.5 days, ec = 0.20 ± 0.04, and Kc = 27.6 ± 2.5 m s-1. Adopting a stellar mass of 1.07 M⊙, we find Mc sin i = 1.57MJup and a semimajor axis of 2.56 AU. The second companion to HD 38529 has Pc = 2174 ± 30 days, ec = 0.36 ± 0.05, and Kc = 170.5 ± 9 m s-1. The assumed mass of 1.39 M⊙ for HD 38529 yields Mc sin i = 12.7MJup and a semimajor axis of 3.68 AU. Photometric observations at Fairborn Observatory reveal low-amplitude brightness variations in HD 40979 and HD 38529 due to rotational modulation in the visibility of photospheric starspots, and they yield rotation periods of 7.0 and 35.7 days, respectively, very different from the planetary orbital periods. The orbital parameters of these two systems are compared with updated parameters for all of the known multiple-planet systems. Updated velocities are provided for the Υ Andromedae system.info:eu-repo/semantics/publishe
Hipparcos astrometric orbits for two brown dwarf companions: HD 38529 and HD 168443
Get PDFContext.HD 38529 and HD 168443 have previously been identified as
systems with two substellar companion candidates using precise radial velocity
measurements.Aims.We want to further constrain their orbits and the nature of the outer companions.Methods.We fit astrometric orbits of the outer substellar companions in the two systems
to the Hipparcos Intermediate Astrometric Data.Results.The fit constrains all possible solutions to a small region in the
parameter space of the two missing orbital parameters (inclination i and
ascending node Ω).
This can be interpreted as a possible real detection of the
astrometric signatures of the companions in the Hipparcos data, although there
is still a 14–18% chance that the signal is not detectable in the data,
according to an F-test. However, even in the case of a non-detection of the
companion signal in the astrometric data, the knowledge of the spectroscopic
orbital parameters enables us to place tight constraints on these two missing
parameters, so that the astrometric orbit is fully determined (with
confidence levels of around 80% for HD 38529, 95% for HD 168443).
Inclinations derived from these astrometric fits enable us to calculate
masses for the substellar companions rather than lower or upper limits.
The best fit solution for HD 38529, (i, Ω) = (160°, 52°),
yields a mass of 37 MJup for the
outer companion.
For HD 168443, we derive best fit parameters of
(i, Ω) = (150°, 19°), which imply a companion mass of
MJup.Conclusions.The outer companions in both systems are thus brown dwarfs
Host Star Properties And Transit Exclusion For The HD 38529 Planetary System
Get PDFThe transit signature of exoplanets provides an avenue through which characterization of exoplanetary properties may be undertaken, such as studies of mean density, structure, and atmospheric composition. The Transit Ephemeris Refinement and Monitoring Survey is a program to expand the catalog of transiting planets around bright host stars by refining the orbits of known planets discovered with the radial velocity technique. Here we present results for the HD 38529 system. We determine fundamental properties of the host star through direct interferometric measurements of the radius and through spectroscopic analysis. We provide new radial velocity measurements that are used to improve the Keplerian solution for the two known planets, and we find no evidence for a previously postulated third planet. We also present 12 years of precision robotic photometry of HD 38529 that demonstrate the inner planet does not transit and the host star exhibits cyclic variations in seasonal mean brightness with a timescale of approximately six years
Mutual inclinations between giant planets and their debris discs in HD 113337 and HD 38529
Get PDFHD 113337 and HD 38529 host pairs of giant planets, a debris disc, and wide M-type stellar companions. We measure the disc orientation with resolved images from Herschel and constrain the three-dimensional orbits of the outer planets with Gaia DR2 and Hipparcos astrometry. Resolved disc modelling leaves degeneracy in the disc orientation, so we derive four separate planet-disc mutual inclination (∆I) solutions. The most aligned solutions give ∆I = 17°-32° for HD 113337 and ∆I = 21°-45○ for HD 38529 (both 1σ). In both systems, there is a small probability (<0.3 per cent) that the planet and disc are nearly aligned (∆I < 3○). The stellar and planetary companions cause the orbits of disc material to precess about a plane defined by the forced inclination. We determine this as well as the precession time-scale to interpret the mutual inclination results. We find that the debris discs in both systems could be warped via joint influences of the outer planet and stellar companion, potentially explaining the observed misalignments. However, this requires HD 113337 to be old (0.8-1.7 Gyr), whereas if young (14-21 Myr), the observed misalignment in HD 113337 could be inherited from the protoplanetary disc phase. For both systems, the inclination of the stellar spin axis is consistent with the disc and outer planet inclinations, which instead supports system-wide alignment or near alignment. High-resolution observations of the discs and improved constraints on the planetary orbits would provide firmer conclusions about the (mis)alignment status
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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