Characterizing Transiting Extrasolar Planets

The detection of the first planets outside our solar system two decades ago has spurred growing efforts to detect new planets. Thanks to improvements in spectroscopic and photometric technology fed by ten years experience, more and more planets have been found showing an astounding diversity of physical and orbital characteristics. At the same time, great efforts are spent on the characterization of the known planets in order to understand their composition, especially as this can give insights into planet formation processes. The work presented in this thesis is pointed on one side towards the identification and confirmation of new exoplanets, on the other side towards the characterization of known transiting exoplanetary systems. Regarding the first science case, two different works are reported: the discovery of two new planetary systems within the HATSouth (HATS-15 and HATS-16) collaboration and the confirmation of the planetary nature of the Kepler candidate Kepler-432 b. HATS-15 b and HATS-16 b are two massive planets (with masses of ∼ 2.2 MJup and ∼ 3.3 MJup respectively) orbiting around two old G-type stars (age ∼ 10 Gyr). The short rotation period of HATS-16 b points towards a tidal interaction with the planet that resulted in a spun-up. Kepler-432 is a sub-giant star ascending the red-giant branch. It hosts a massive planet (∼ 5 MJup) orbiting on a moderately eccentric orbit. Among other planets around evolved stars, Kepler-432 b is extremely rare being one of the few on a tight orbit (a < 0.5 au), challenging evolution and dynamical theories. The main idea of the latter project is to perform follow-up observations of known transiting extrasolar planets in order to accurately characterize their systems. Further information, such as planetary atmosphere composition or stellar spin-orbit alignment, can be achieved by using different observing strategies: monitoring the same transit with two different facilities or perform simultaneous observations in different bands with instruments as BUSCA (CAHA) or GROND (La Silla). The characterization of six planetary systems and the successful exploit of the two observing strategies are presented. Two planetary systems were observed simultaneously from two sites: HAT-P-16 and WASP-21. For HAT-P-23, WASP-45, WASP-46 and WASP-48 we obtained multi-band observations. For all the systems studied, a preciser measurements for the physical parameters was obtained. Moreover, all the planets are smaller than previously known. The planetary densities are therefore higher and in some cases the variation is significant (e.g. WASP-45 b), leading to a planet’s size compatible with a model predicting a core 50 M⊕

Kepler-432 b: a massive planet in a highly eccentric orbit transiting a red giant

We report the first disclosure of the planetary nature of Kepler-432 b (aka Kepler object of interest KOI-1299.01). We accurately constrained its mass and eccentricity by high-precision radial velocity measurements obtained with the CAFE spectrograph at the CAHA 2.2-m telescope. By simultaneously fitting these new data and Kepler photometry, we found that Kepler-432 b is a dense transiting exoplanet with a mass of Mp = 4.87 +/- 0.48 MJup and radius of Rp = 1.120 +/- 0.036 RJup. The planet revolves every 52.5 d around a K giant star that ascends the red giant branch, and it moves on a highly eccentric orbit with e = 0.535 +/- 0.030. By analysing two NIR high-resolution images, we found that a star is located at 1.1 from Kepler-432, but it is too faint to cause significant effects on the transit depth. Together with Kepler-56 and Kepler-91, Kepler-432 occupies an almost-desert region of parameter space, which is important for constraining the evolutionary processes of planetary systems.Comment: 4 pages, 5 figures, accepted for publication in A&A Letters. Also see the companion paper by Ortiz et a

Qatar Exoplanet Survey : Qatar-3b, Qatar-4b and Qatar-5b

We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey (QES). The three planets belong to the hot Jupiter family, with orbital periods of $P_{Q3b}$=2.50792 days, $P_{Q4b}$=1.80539 days, and $P_{Q5b}$=2.87923 days. Follow-up spectroscopic observations reveal the masses of the planets to be $M_{Q3b}$=4.31$\pm0.47$ $M_{\rm J}$, $M_{Q4b}$=6.10$\pm0.54$ $M_{\rm J}$, and $M_{Q5b}$ = 4.32$\pm0.18$ $M_{\rm J}$, while model fits to the transit light curves yield radii of $R_{Q3b}$ = 1.096$\pm0.14$ $R_{\rm J}$, $R_{Q4b}$ = 1.135$\pm0.11$ $R_{\rm J}$, and $R_{Q5b}$ = 1.107$\pm0.064$ $R_{\rm J}$. The host stars are low-mass main sequence stars with masses and radii $M_{Q3}$ = 1.145$\pm0.064$ $M_{\odot}$, $M_{Q4}$ = 0.896$\pm0.048$ $M_{\odot}$, $M_{Q5}$ = 1.128$\pm0.056$ $M_{\odot}$ and $R_{Q3}$ = 1.272$\pm0.14$ $R_{\odot}$, $R_{Q4}$ = 0.849$\pm0.063$ $R_{\odot}$ and $R_{Q5}$ = 1.076$\pm0.051$ $R_{\odot}$ for Qatar-3, 4 and 5 respectively. The V magnitudes of the three host stars are $V_{Q3}$=12.88, $V_{Q4}$=13.60, and $V_{Q5}$=12.82. All three new planets can be classified as heavy hot Jupiters (M > 4 $M_{J}$).Comment: 13Pages, 8Figure

Weather on the Nearest Brown Dwarfs: Resolved Simultaneous Multi-Wavelength Variability Monitoring of WISE J104915.57-531906.1AB

We present two epochs of MPG/ESO 2.2m GROND simultaneous 6-band ($r'i'z'JHK$) photometric monitoring of the closest known L/T transition brown dwarf binary WISE J104915.57-531906.1AB. We report here the first resolved variability monitoring of both the T0.5 and L7.5 components. We obtained 4 hours of focused observations on the night of UT 2013-04-22, as well as 4 hours of defocused (unresolved) observations on the night of UT 2013-04-16. We note a number of robust trends in our light curves. The $r'$ and $i'$ light curves appear to be anticorrelated with $z'$ and $H$ for the T0.5 component and in the unresolved lightcurve. In the defocused dataset, $J$ appears correlated with $z'$ and $H$ and anticorrelated with $r'$ and $i'$, while in the focused dataset we measure no variability for $J$ at the level of our photometric precision, likely due to evolving weather phenomena. In our focused T0.5 component lightcurve, the $K$ band lightcurve displays a significant phase offset relative to both $H$ and $z'$. We argue that the measured phase offsets are correlated with atmospheric pressure probed at each band, as estimated from 1D atmospheric models. We also report low-amplitude variability in $i'$ and $z'$ intrinsic to the L7.5 component.Comment: 14 pages, 5 figures, accepted to ApJ Letter

HATS-18 b: An Extreme Short--Period Massive Transiting Planet Spinning Up Its Star

We report the discovery by the HATSouth network of HATS-18 b: a 1.980 +/- 0.077 Mj, 1.337 +0.102 -0.049 Rj planet in a 0.8378 day orbit, around a solar analog star (mass 1.037 +/- 0.047 Msun, and radius 1.020 +0.057 -0.031 Rsun) with V=14.067 +/- 0.040 mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range 6.5 <= lg(Q*/k_2) <= 7 even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star--planet interactions, be they gravitational, magnetic or radiative, as well as planet formation and migration theories.Comment: Submitted. 12 pages, 9 figures, 5 table

HATS-4b: A dense hot Jupiter transiting a super metal-rich G star

We report the discovery by the HATSouth survey of HATS-4b, an extrasolar planet transiting a V = 13.46 mag G star. HATS-4b has a period of P ≈ 2.5167 days, mass of Mp ≈ 1.32 MJup, radius of Rp ≈ 1.02 RJup, and density of ρp = 1.55 ± 0.16 g cm−3 ≈ 1.24 ρJup. The host star has a mass of 1.00 M , a radius of 0.92 R , and a very high metallicity [Fe/H]= 0.43 ± 0.08. HATS-4b is among the densest known planets with masses between 1 and 2 MJ and is thus likely to have a significant content of heavy elements of the order of 75 M⊕. In this paper we present the data reduction, radial velocity measurements, and stellar classification techniques adopted by the HATSouth survey for the CORALIE spectrograph. We also detail a technique for simultaneously estimating v sin i and macroturbulence using high resolution spectra.Development of the HATSouth project was funded by NSFMRI grant NSF/AST-0723074, operations have been supported by NASA grants NNX09AB29G and NNX12AH91H, and followup observations receive partial support from grant NSF/AST- 1108686. A.J. acknowledges support from FONDECYT project 1130857, BASAL CATA PFB-06, and projects IC120009 “Millennium Institute of Astrophysics (MAS)” and P10-022-F of the Millennium Science Initiative, Chilean Ministry of Economy. R.B. and N.E. are supported by CONICYT-PCHA/Doctorado Nacional. R.B. acknowledges additional support from Nucleus P10-022-F of the Millennium Science Initiative, Chilean Ministry of Economy. V.S. acknowledges support form BASAL CATA PFB-06. M.R. acknowledges support from FONDECYT postdoctoral fellowship 3120097. Australian access to the Magellan Telescopeswas supported through the National Collaborative Research Infrastructure Strategy of the Australian Federal Government. Work at the Australian National University is supported by ARC Laureate Fellowship Grant FL0992131. We acknowledge the use of the AAVSO Photometric All-Sky Survey (APASS), funded by the RobertMartin Ayers Sciences Fund, NASA’s Astrophysics Data System Bibliographic Services, and the SIMBADdatabase, operated at CDS, Strasbourg, France. Operations at the MPG/ESO 2.2 m Telescope are jointly performed by the Max Planck Gesellschaft and the European Southern Observatory

HATS-5b: A transiting hot saturn from the HATsouth survey

We report the discovery of HATS-5b, a transiting hot Saturn orbiting a G-type star, by the HATSouth survey. HATS-5b has a mass of Mp 0.24 MJ, radius of Rp 0.91 R J, and transits its host star with a period of P 4.7634 days. The radius of HATS-5b is consistent with both theoretical and empirical models. The host star has a V-band magnitude of 12.6, mass of 0.94 M ⊙, and radius of 0.87 R. The relatively high scale height of HATS-5b and the bright, photometrically quiet host star make this planet a favorable target for future transmission spectroscopy follow-up observations. We reexamine the correlations in radius, equilibrium temperature, and metallicity of the close-in gas giants and find hot Jupiter-mass planets to exhibit the strongest dependence between radius and equilibrium temperature. We find no significant dependence in radius and metallicity for the close-in gas giant population.Development of the HATSouth project was funded by NSF MRI grant NSF/AST-0723074, operations are supported by NASA grant NNX12AH91H, and follow-up observations receive partial support from grant NSF/AST-1108686. Work at the Australian National University is supported by ARC Laureate Fellowship Grant FL0992131. A.J. acknowledges support from FONDECYT project 1130857, BASAL CATA PFB-06, and projects IC120009 “Millennium Institute of Astrophysics (MAS)” and P10-022-F of the Millennium Science Initiative, Chilean Ministry of Economy. V.S. acknowledges support form BASAL CATA PFB-06. M.R. acknowledges support from FONDECYT postdoctoral fellowship No3120097. R.B. and N.E. acknowledge support from CONICYT-PCHA/Doctorado Nacional and Fondecyt project 1130857. We acknowledge the use of the AAVSO Photometric All-Sky Survey (APASS), funded by the Robert Martin Ayers Sciences Fund, and the SIMBAD database, operated at CDS, Strasbourg, France. Operations at the MPG/ESO 2.2 m telescope are jointly performed by the Max Planck Gesellschaft and the European Southern Observatory. Australian access to the Magellan Telescopes was supported through the National Collaborative Research Infrastructure Strategy of the Australian Federal Government

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