The Mass Of Hd 38529c From Hubble Space Telescope Astrometry And High-Precision Radial Velocities

dc.contributor.utaustinauthorBenedict, G. Fritzen_US
dc.contributor.utaustinauthorMcArthur, Barbara E.en_US
dc.creatorBenedict, G. Fritzen_US
dc.creatorMcArthur, Barbara E.en_US
dc.creatorBean, Jacob L.en_US
dc.creatorBarnes, Roryen_US
dc.creatorHarrison, Thomas E.en_US
dc.creatorHatzes, Artieen_US
dc.creatorMartioli, Ederen_US
dc.creatorNelan, Edmund P.en_US
dc.description.abstractHubble Space Telescope Fine Guidance Sensor astrometric observations of the G4 IV star HD 38529 are combined with the results of the analysis of extensive ground-based radial velocity (RV) data to determine the mass of the outermost of two previously known companions. Our new RVs obtained with the Hobby-Eberly Telescope and velocities from the Carnegie-California group now span over 11 yr. With these data we obtain improved RV orbital elements for both the inner companion, HD 38529b, and the outer companion, HD 38529c. We identify a rotational period of HD 38529 (P(rot) = 31.65 +/- 0(d).17) with Fine Guidance Sensor photometry. The inferred star spot fraction is consistent with the remaining scatter in velocities being caused by spot-related stellar activity. We then model the combined astrometric and RV measurements to obtain the parallax, proper motion, perturbation period, perturbation inclination, and perturbation size due to HD 38529c. For HD 38529c we find P = 2136.1 +/- 0.3 d, perturbation semimajor axis alpha = 1.05 +/- 0.06 mas, and inclination i = 48 degrees.3 +/- 3 degrees.7. Assuming a primary mass M(*) = 1.48 M(circle dot), we obtain a companion mass M(c) = 17.6(1.2)(+1.5) M(Jup), 3 sigma above a 13 M(Jup) deuterium burning, brown dwarf lower limit. Dynamical simulations incorporating this accurate mass for HD 38529c indicate that a near-Saturn mass planet could exist between the two known companions. We find weak evidence of an additional low amplitude signal that can be modeled as a planetary-mass (similar to 0.17 M(Jup)) companion at P similar to 194 days. Including this component in our modeling lowers the error of the mass determined for HD 38529c. Additional observations (RVs and/or Gaia astrometry) are required to validate an interpretation of HD 38529d as a planetary-mass companion. If confirmed, the resulting HD 38529 planetary system may be an example of a >Packed Planetary System.>en_US
dc.description.departmentMcDonald Observatoryen_US
dc.description.sponsorshipSpace Telescope Science Institute GO-10610, GO-10989, GO-11210en_US
dc.description.sponsorshipNASA NAS5-26555en_US
dc.description.sponsorshipDFG GRK 1351, RE 1664/4-1en_US
dc.description.sponsorshipEuropean Commission PIFF-GA-2009-234866en_US
dc.identifier.citationBenedict, G. Fritz, Barbara E. McArthur, Jacob L. Bean, Rory Barnes, Thomas E. Harrison, Artie Hatzes, Eder Martioli, and Edmund P. Nelan. >The mass of HD 38529c from Hubble space telescope astrometry and high-precision radial velocities.> The Astronomical Journal, Vol. 139, No. 5 (May., 2010): 1844.en_US
dc.relation.ispartofserialAstronomical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectbrown dwarfsen_US
dc.subjectstars: distancesen_US
dc.subjectstars: individual (hden_US
dc.subjectstars: late-typeen_US
dc.subjecttechniques: interferometricen_US
dc.subjectradial velocitiesen_US
dc.subjecthobby-eberly telescopeen_US
dc.subjectcandidate exoplanet companionen_US
dc.subjectplanetary systemsen_US
dc.subjectbrown-dwarf deserten_US
dc.subjectcool starsen_US
dc.subjectpredicting planetsen_US
dc.subjectstellar companionsen_US
dc.subjectchara arrayen_US
dc.subjecthost starsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleThe Mass Of Hd 38529c From Hubble Space Telescope Astrometry And High-Precision Radial Velocitiesen_US

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