Browsing by Subject "techniques: photometric"

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An Ancient Extrasolar System With Five Sub-Earth-Size Planets
(2015-02) Campante, T. L.; Barclay, Thomas; Swift, Jonathan J.; Huber, Daniel; Adibekyan, V. Z.; Cochran, William; Burke, C. J.; Isaacson, Howard; Quintana, Elisa V.; Davies, G. R.; Aguirre, V. S.; Ragozzine, D.; Riddle, R.; Baranec, C.; Basu, S.; Chaplin, W. J.; Christensen-Dalsgaard, J.; Metcalfe, T. S.; Bedding, T. R.; Handberg, R.; Stello, D.; Brewer, J. M.; Hekker, S.; Karoff, C.; Kolbl, R.; Law, N. M.; Lundkvist, M.; Miglio, A.; Rowe, Jason F.; Santos, N. C.; Van Laerhoven, C.; Arentoft, T.; Elsworth, Y. P.; Fischer, Debra A.; Kawaler, Steven D.; Kjeldsen, H.; Lund, M. N.; Marcy, Geoffrey W.; Sousa, S. G.; Sozzetti, A.; White, T. R.; Cochran, William
The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 +/- 1.0Gyr for the host star, indicating that Kepler-444 formed when the universe was less than 20% of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the universe's 13.8 billion year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation.
The California Planet Survey. I. Four New Giant Exoplanets
(2010-10) Howard, Andrew W.; Johnson, John A.; Marcy, Geoffrey W.; Fischer, Debra A.; Wright, Jason T.; Bernat, David; Henry, Gregory W.; Peek, Kathryn M. G.; Isaacson, Howard; Apps, Kevin; Endl, Michael; Cochran, William D.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.; Endl, Michael; Cochran, William D.
We present precise Doppler measurements of four stars obtained during the past decade at Keck Observatory by the California Planet Survey (CPS). These stars, namely, HD 34445, HD 126614, HD 13931, and Gl 179, all show evidence for a single planet in Keplerian motion. We also present Doppler measurements from the Hobby-Eberly Telescope (HET) for two of the stars, HD 34445 and Gl 179, that confirm the Keck detections and significantly refine the orbital parameters. These planets add to the statistical properties of giant planets orbiting near or beyond the ice line, and merit follow-up by astrometry, imaging, and space-borne spectroscopy. Their orbital parameters span wide ranges of planetary minimum mass (M sin i = 0.38-1.9 M(Jup)), orbital period (P = 2.87-11.5 yr), semimajor axis (a = 2.1-5.2 AU), and eccentricity (e = 0.02-0.41). HD 34445 b (P = 2.87 yr, M sin i = 0.79 MJup, e = 0.27) is a massive planet orbiting an old, G-type star. We announce a planet, HD 126614 Ab, and an M dwarf, HD 126614 B, orbiting the metal-rich star HD 126614 (which we now refer to as HD 126614 A). The planet, HD 126614 Ab, has minimum mass M sin i = 0.38 MJup and orbits the stellar primary with period P = 3.41 yr and orbital separation a = 2.3 AU. The faint M dwarf companion, HD 126614 B, is separated from the stellar primary by 489 mas (33 AU) and was discovered with direct observations using adaptive optics and the PHARO camera at Palomar Observatory. The stellar primary in this new system, HD 126614 A, has the highest measured metallicity ([ Fe/ H] = + 0.56) of any known planet-bearing star. HD 13931 b (P = 11.5 yr, M sin i = 1.88 MJup, e = 0.02) is a Jupiter analog orbiting a near solar twin. Gl 179 b (P = 6.3 yr, M sin i = 0.82 M(Jup), e = 0.21) is a massive planet orbiting a faint M dwarf. The high metallicity of Gl 179 is consistent with the planet-metallicity correlation among M dwarfs, as documented recently by Johnson & Apps.
CfAIR2: Near-Infrared Light Curves of 94 Type Ia Supernovae
(2015-09) Friedman, Andrew S.; Wood-Vasey, W. M.; Marion, G. H.; Challis, Peter; Mandel, Kaisey S.; Bloom, Joshua S.; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcom; Foley, Ryan J.; Klein, Christopher R.; Starr, Dan L.; Morgan, Adam; Rest, Armin; Blake, Cullen H.; Miller, Adam A.; Falco, Emilio E.; Wyatt, William F.; Mink, Jessica; Skrutskie, Mmichael F.; Kirshner, Rrobert P.; Marion, G. H.
CfAIR2 is a large, homogeneously reduced set of near-infrared (NIR) light curves (LCs) for Type Ia supernovae (SNe Ia) obtained with the 1.3 m Peters Automated InfraRed Imaging TELescope. This data set includes 4637 measurements of 94 SNe Ia and 4 additional SNe Iax observed from 2005 to 2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z similar to 0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the LCs begin before the time of maximum, and the coverage typically contains similar to 13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for SN cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the SN cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.
Characterization Of The HD 17156 Planetary System
(2009-08) Barbieri, M.; Alonso, R.; Desidera, S.; Sozzetti, A.; Fiorenzano, A. F. M.; Almenara, J. M.; Cecconi, M.; Claudi, R. U.; Charbonneau, D.; Endl, M.; Granata, V.; Gratton, R.; Laughlin, G.; Loeillet, B.; Exoplanet Amateur, Consortium; Endl, M.
Aims. We present data to improve the known parameters of the HD 17156 system (peculiar due to the eccentricity and long orbital period of its transiting planet) and constrain the presence of stellar companions. Methods. Photometric data were acquired for 4 transits, and high precision radial velocity measurements were simultaneously acquired with the SARG spectrograph at TNG for one transit. The template spectra of HD 17156 was used to derive effective temperature, gravity, and metallicity. A fit of the photometric and spectroscopic data was performed to measure the stellar and planetary radii, and the spin-orbit alignment. Planet orbital elements and ephemeris were derived from the fit. Near infrared adaptive optic images were acquired with the AdOpt module of TNG. Results. We found that the star has a radius of R(S) = 1.44 +/- 0.03 R(circle dot) and the planet R(P) = 1.02 +/- 0.08 R(J). The transit ephemeris is T(c) = 2 454 756.73134 +/- 0.00020 + N . 21.21663 +/- 0.00045 BJD. Analysis of the Rossiter-Mclaughlin effect shows that the system is spin orbit aligned with an angle beta = 4.8 degrees +/- 5.3 degrees. The analysis of high resolution images did not reveal any stellar companion with a projected separation between of 150 and 1 000 AU from HD 17156.
Color Variability Of HBC 722 In The Post-Outburst Phases
(2015) Baek, Giseon; Pak, Soojong; Green, Joel D.; Meschiari, Stefano; Lee, Jeong-Eun; Jeon, Yiseul; Choi, Changsu; Im, Myungshin; Sung, Hyun-Il; Park, Won-Kee; Green, Joel D.; Meschiari, Stefano
We carried out photometric observations for HBC 722 in the Sloan Digital Sky Survey r, i, and z bands from 2011 April to 2013 May with the Camera for QUasars in EArly uNiverse attached to the 2.1 m Otto Struve telescope at McDonald Observatory. The post-outburst phenomena were classified into five phases according to not only brightness but also color variations, which might be caused by physical changes in the emitting regions of optical and near-infrared bands. A series of spectral energy distributions (SEDs) is presented to support color variations and track the time evolution of the SED in optical/near-infrared bands after the outburst. Given two years of data, possible periodicities of r, i, and z bands were checked. We found three families of signals around similar to 6, similar to 10, and similar to 1 days in three bands, which is broadly consistent with Green et al. We also examined short-term variability (intra-day and day scales) to search for evidences of flickering by using the micro-variability method. We found clear signs of day scale variability and weak indications of intra-day scale fluctuations, which implies that the flickering event occurs in HBC 722 after outburst.
The Evolving Activity Of The Dynamically Young Comet C/2009 P1 (Garradd)
(2014-05) Bodewits, D.; Farnham, T. L.; A'Hearn, M. F.; Feaga, L. M.; McKay, A.; Schleicher, D. G.; Sunshine, J. M.; McKay, A.
We used the Ultraviolet-Optical Telescope on board Swift to observe the dynamically young comet C/2009 P1 (Garradd) from a heliocentric distance of 3.5 AU pre-perihelion until 4.0 AU outbound. At 3.5 AU pre-perihelion, comet Garradd had one of the highest dust-to-gas ratios ever observed, matched only by comet Hale-Bopp. The evolving morphology of the dust in its coma suggests an outburst that ended around 2.2 AU pre-perihelion. Comparing slit-based measurements and observations acquired with larger fields of view indicated that between 3 AU and 2 AU pre-perihelion a significant extended source started producing water in the coma. We demonstrate that this source, which could be due to icy grains, disappeared quickly around perihelion. Water production by the nucleus may be attributed to a constantly active source of at least 75 km(2), estimated to be > 20% of the surface. Based on our measurements, the comet lost 4 x 10(11) kg of ice and dust during this apparition, corresponding to at most a few meters of its surface. Even though this was likely not the comet's first passage through the inner solar system, the activity of Garradd was complex and changed significantly during the time it was observed.
The Fast Declining Type Ia Supernova 2003Gs, And Evidence For A Significant Dispersion In Near-Infrared Absolute Magnitudes Of Fast Decliners At Maximum Light
(2009-12) Krisciunas, Kevin; Marion, G. H.; Suntzeff, Nicholas B.; Blanc, Guillaume; Bufano, Filomena; Candia, Pablo; Cartier, Regis; Elias-Rosa, Nancy; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Serio; Gooding, Samuel D.; Hamuy, Mario; Knox, Ethan A.; Milne, Peter A.; Morrell, Nidia; Phillips, Mark M.; Stritzinger, Maximillian; Thomas-Osip, Joanna; Marion, G. H.
We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days after T(B(max)). We also obtained near-IR photometry on 21 nights. SN 2003gs was the first fast declining Type Ia SN that has been well observed since SN 1999by. While it was subluminous in optical bands compared to more slowly declining Type Ia SNe, it was not subluminous at maximum light in the near-IR bands. There appears to be a bimodal distribution in the near-IR absolute magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR after T(B(max)) are subluminous in the all bands. Those that peak in the near-IR prior to T(B(max)), such as SN 2003gs, have effectively the same near-IR absolute magnitudes at maximum light regardless of the decline rate Delta m(15)(B). Near-IR spectral evidence suggests that opacities in the outer layers of SN 2003gs are reduced much earlier than for normal Type Ia SNe. That may allow gamma rays that power the luminosity to escape more rapidly and accelerate the decline rate. This conclusion is consistent with the photometric behavior of SN 2003gs in the IR, which indicates a faster than normal decline from approximately normal peak brightness.
Five Kepler Target Stars That Show Multiple Transiting Exoplanet Candidates
(2010-12) Steffen, Jason H.; Batalha, Natalie M.; Borucki, William J.; Buchhave, Lars A.; Caldwell, Douglas A.; Cochran, William D.; Endl, Michael; Fabrycky, Daniel C.; Fressin, Francois; Ford, Eric B.; Fortney, Jonathan J.; Haas, Michael J.; Holman, Matthew J.; Howell, Steve B.; Isaacson, Howard; Jenkins, Jon M.; Koch, David; Latham, David W.; Lissauer, Jack J.; Moorhead, Althea V.; Morehead, Robert C.; Marcy, Geoffrey; MacQueen, Phillip J.; Quinn, Samuel N.; Ragozzine, Darin; Rowe, Jason F.; Sasselov, Dimitar D.; Seager, Sara; Torres, Guillermo; Welsh, William F.; Cochran, William D.; Endl, Michael; MacQueen, Phillip J.
We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets and provide new insights into the formation and dynamical evolution of planetary systems. We discuss the methods used to identify multiple transiting objects from the Kepler photometry as well as the false-positive rejection methods that have been applied to these data. One system shows transits from three distinct objects while the remaining four systems show transits from two objects. Three systems have planet candidates that are near mean motion commensurabilities-two near 2:1 and one just outside 5:2. We discuss the implications that multi-transiting systems have on the distribution of orbital inclinations in planetary systems, and hence their dynamical histories, as well as their likely masses and chemical compositions. A Monte Carlo study indicates that, with additional data, most of these systems should exhibit detectable transit timing variations (TTVs) due to gravitational interactions, though none are apparent in these data. We also discuss new challenges that arise in TTV analyses due to the presence of more than two planets in a system.
Frozen To Death? Detection Of Comet Hale-Bopp At 30.7 AU (Research Note)
(2011-07) Szabo, G. M.; Sarneczky, K.; Kiss, L. L.; Szabo, G. M.
Context. Comet Hale-Bopp 9C/1995 O1) has been the most interesting comet ever encountered by modern astronomy, which continued to display significant activity at a solar distance of 25.7 AU. It is unclear when and how this activity will finally cease. Aims. We present new observations with the ESO 2.2 m telescope at La Silla to monitor the activity of Hale-Bopp at 30.7 AU solar distance. Methods. On 2010-12-04, 26 CCD images were taken with 180 s exposure times for photometry and morphology. Results. The comet was detected in R and had a total brightness of 23(m).3 +/- 0(m).2, which corresponds to an absolute brightness of R(1, 1, 0) = 8(m).3. The profile of the coma was star-like at a seeing of 1 ''.9, without any evidence of a coma or tail extending farther than 2 ''.5 (= 55 000 km in projection) and exceeding 26.5 mag/arcs(2) surface brightness. The measured total brightness corresponds to a relative total reflecting surface, a(R)C, of 485 km(2), nine times less than three years before. The calculated a(R)C value would imply a nucleus with 60-65 km radius assuming 4% albedo. This size estimate contradicts significantly the previous results scattering around 35 km. Conclusions. We propose that the comet may still be in a low level of activity, despite the lack of a prominent coma. Alternatively, if the nucleus is already dormant, the albedo should be as high as 13%, assuming a radius of 35 km. With this observation, Hale-Bopp has become the most distant comet ever observed, far beyond the orbit of Neptune.
The Hot-Jupiter Kepler-17b: Discovery, Obliquity from Stroboscopic Starspots, and Atmospheric Characterization
(2011-11) Desert, Jean-Michel; Charbonneau, David; Demory, Brice-Olivier; Ballard, Sarah; Carter, Joshua A.; Fortney, Jonathan J.; Cochran, William D.; Endl, Michael; Quinn, Samuel N.; Isaacson, Howard T.; Fressin, Francois; Buchhave, Lars A.; Latham, David W.; Knutson, Heather A.; Bryson, Stephen T.; Torres, Guillermo; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Caldwell, Douglas A.; Christiansen, Jessie L.; Deming, Drake; Fabrycky, Daniel C.; Ford, Eric B.; Gilliland, Ronald L.; Gillon, Michael; Haas, Michael R.; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David; Lissauer, Jack J.; Lucas, Philip; Mullally, Fergal; MacQueen, Phillip J.; Marcy, Geoffrey W.; Sasselov, Dimitar D.; Seager, Sara; Still, Martin; Tenenbaum, Peter; Uddin, Kamal; Winn, Joshua N.; Cochran, William D.; Endl, Michael; MacQueen, Phillip J.
This paper reports the discovery and characterization of the transiting hot giant exoplanet Kepler-17b. The planet has an orbital period of 1.486 days, and radial velocity measurements from the Hobby-Eberly Telescope show a Doppler signal of 419.5(-15.6)(+13.3) m s(-1). From a transit-based estimate of the host star's mean density, combined with an estimate of the stellar effective temperature T-eff = 5630 +/- 100 from high-resolution spectra, we infer a stellar host mass of 1.06 +/- 0.07 M-circle dot and a stellar radius of 1.02 +/- 0.03 R-circle dot. We estimate the planet mass and radius to be M-P = 2.45 +/- 0.11 M-J and R-P = 1.31 +/- 0.02 R-J. The host star is active, with dark spots that are frequently occulted by the planet. The continuous monitoring of the star reveals a stellar rotation period of 11.89 days, eight times the planet's orbital period; this period ratio produces stroboscopic effects on the occulted starspots. The temporal pattern of these spot-crossing events shows that the planet's orbit is prograde and the star's obliquity is smaller than 15 degrees. We detected planetary occultations of Kepler-17b with both the Kepler and Spitzer Space Telescopes. We use these observations to constrain the eccentricity, e, and find that it is consistent with a circular orbit (e < 0.011). The brightness temperatures of the planet's infrared bandpasses are T-3.6 mu m = 1880 +/- 100 K and T-4.5 mu m = 1770 +/- 150 K. We measure the optical geometric albedo A(g) in the Kepler bandpass and find A(g) = 0.10 +/- 0.02. The observations are best described by atmospheric models for which most of the incident energy is re-radiated away from the day side.
Kepler's First Rocky Planet: Kepler-10B
(2011-03) Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen T.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard, Jorgen; Ciardi, David; Dunham, Edward W.; Fressin, Francois; Gautier, Thomas N., III; Gilliland, Ronald L.; Haas, Michael R.; Howell, Steve B.; Jenkins, Jon M.; Kjeldsen, Hans; Koch, David G.; Latham, David W.; Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason F.; Sasselov, Dimitar D.; Seager, Sara; Steffen, Jason H.; Torres, Guillermo; Basri, Gibor S.; Brown, Timothy M.; Charbonneau, David; Christiansen, Jessie; Clarke, Bruce; Cochran, William D.; Dupree, Andrea; Fabrycky, Daniel C.; Fischer, Debra; Ford, Eric B.; Fortney, Jonathan; Girouard, Forrest R.; Holman, Matthew J.; Johnson, John; Isaacson, Howard; Klaus, Todd C.; Machalek, Pavel; Moorehead, Althea V.; Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken, Joseph; Quinn, Samuel; VanCleve, Jeffrey; Walkowicz, Lucianne M.; Welsh, William F.; Devore, Edna; Gould, Alan; Cochran, William D.
NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: (1) a 152 +/- 4 ppm dimming lasting 1.811 +/- 0.024 hr with ephemeris T [BJD] = 2454964.57375(-0.00082)(+0.00060) + N * 0.837495(-0.000005)(+0.000004) days and (2) a 376 +/- 9 ppm dimming lasting 6.86 +/- 0.07 hr with ephemeris T [BJD] = 2454971.6761(-0.0023)(+0.0020) + N * 45.29485(-0.00076)(+0.00065) days. Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1 minute cadence for > 4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9 +/- 4.5 Gyr) but otherwise Sun-like main-sequence star with T-eff = 5627 +/- 44 K, M-star = 0.895 +/- 0.060M(circle dot), and R-star = 1.056 +/- 0.021R(circle dot). Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: M-P = 4.56(-1.29)(+1.17) M-circle plus, R-P = 1.416(-0.036)(+0.033) R-circle plus, and rho P = 8.8(-2.9)(+2.1) g cm(-3). Kepler-10b is the smallest transiting exoplanet discovered to date.
Kepler-14B: A Massive Hot Jupiter Transiting An F Star in A Close Visual Binary
(2011-11) Buchhave, Lars A.; Latham, David W.; Carter, Joshua A.; Desert, Jean-Michel; Torres, Guillermo; Adams, Elisabeth R.; Bryson, Stephen T.; Charbonneau, David B.; Ciardi, David R.; Kulesa, Craig; Dupree, Andrea K.; Fischer, Debra A.; Fressin, Francois; Gautier, Thomas N., III; Gilliland, Ronald L.; Howell, Steve B.; Isaacson, Howard; Jenkins, Jon M.; Marcy, Geoffrey W.; McCarthy, Donald W.; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Brown, Timothy M.; Caldwell, Douglas A.; Christiansen, Jessie L.; Cochran, William D.; Deming, Drake; Dunham, Edward W.; Everett, Mark; Ford, Eric B.; Fortney, Jonathan J.; Geary, John C.; Girouard, Forrest R.; Haas, Michael R.; Holman, Matthew J.; Horch, Elliott; Klaus, Todd C.; Knutson, Heather A.; Koch, David G.; Kolodziejczak, Jeffrey; Lissauer, Jack J.; Machalek, Pavel; Mullally, Fergal; Still, Martin D.; Quinn, Samuel N.; Seager, Sara; Thompson, Susan E.; Van Cleve, Jeffrey; Cochran, William D.
We present the discovery of a hot Jupiter transiting an F star in a close visual (0 ''.3 sky projected angular separation) binary system. The dilution of the host star's light by the nearly equal magnitude stellar companion (similar to 0.5 mag fainter) significantly affects the derived planetary parameters, and if left uncorrected, leads to an underestimate of the radius and mass of the planet by 10% and 60%, respectively. Other published exoplanets, which have not been observed with high-resolution imaging, could similarly have unresolved stellar companions and thus have incorrectly derived planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790 days and, correcting for the dilution, has a mass of M-p = 8.40(-0.34)(+ 0.35) M-J and a radius of R-p = 1.136(-0.054)(+ 0.073) R-J, yielding a mean density of rho(p) = 7.1 +/- 1.1 g cm(-3).
Kepler-18B, C, and D: A System of Three Planets Confirmed by Transit Timing Variations, Light Curve Validation, Warm-Spitzer Photometry, and Radial Velocity Measurements
(2011-11) Cochran, William D.; Fabrycky, Daniel C.; Torres, Guillermo; Fressin, Francois; Desert, Jean-Michel; Ragozzine, Darin; Sasselov, Dimitar; Fortney, Jonathan J.; Rowe, Jason F.; Brugamyer, Erik J.; Bryson, Stephen T.; Carter, Joshua A.; Ciardi, David R.; Howell, Steve B.; Steffen, Jason H.; Borucki, William J.; Koch, David G.; Winn, Joshua N.; Welsh, William F.; Uddin, Kamal; Tenenbaum, Peter; Still, M.; Seager, Sara; Quinn, Samuel N.; Mullally, F.; Miller, Neil; Marcy, Geoffrey W.; MacQueen, Phillip J.; Lucas, Phillip; Lissauer, Jack J.; Latham, David W.; Knutson, Heather; Kinemuchi, K.; Johnson, John A.; Jenkins, Jon M.; Isaacson, Howard; Howard, Andrew; Horch, Elliott; Holman, Matthew J.; Henze, Christopher E.; Haas, Michael R.; Gilliland, Ronald L.; Gautier, Thomas N., III; Ford, Eric B.; Fischer, Debra A.; Everett, Mark; Endl, Michael; Demory, Brice-Oliver; Deming, Drake; Charbonneau, David; Caldwell, Douglas; Buchhave, Lars; Brown, Timothy M.; Batalha, Natalie; Cochran, William D.; MacQueen, Phillip J.
We report the detection of three transiting planets around a Sun-like star, which we designate Kepler-18. The transit signals were detected in photometric data from the Kepler satellite, and were confirmed to arise from planets using a combination of large transit-timing variations (TTVs), radial velocity variations, Warm-Spitzer observations, and statistical analysis of false-positive probabilities. The Kepler-18 star has a mass of 0.97M(circle dot), a radius of 1.1R(circle dot), an effective temperature of 5345 K, and an iron abundance of [Fe/H] = +0.19. The planets have orbital periods of approximately 3.5, 7.6, and 14.9 days. The innermost planet "b" is a "super-Earth" with a mass of 6.9 +/- 3.4M(circle plus), a radius of 2.00 +/- 0.10R(circle plus), and a mean density of 4.9 +/- 2.4 g cm(3). The two outer planets "c" and "d" are both low-density Neptune-mass planets. Kepler-18c has a mass of 17.3 +/- 1.9 M-circle plus, a radius of 5.49 +/- 0.26R(circle plus), and a mean density of 0.59 +/- 0.07 g cm(3), while Kepler-18d has a mass of 16.4 +/- 1.4 M-circle plus, a radius of 6.98 +/- 0.33 R-circle plus and a mean density of 0.27 +/- 0.03 g cm(.)(3) Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.
Masses, Radii, and Orbits of Small Kepler Planets: the Transition from Gaseous to Rocky Planets
(2014-02) Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Rowe, Jason F.; Jenkins, Jon M.; Bryson, Stephen T.; Latham, David W.; Howell, Steve B.; Gautier, Thomas N., III; Batalha, Natalie M.; Rogers, Leslie; Ciardi, David; Fischer, Debra A.; Gilliland, Ronald L.; Kjeldsen, Hans; Christensen-Dalsgaard, Jorgen; Huber, Daniel; Chaplin, William J.; Basu, Sarbani; Buchhave, Lars A.; Quinn, Samuel N.; Borucki, William J.; Koch, David G.; Hunter, Roger; Caldwell, Douglas A.; Van Cleve, Jeffrey; Kolbl, Rea; Weiss, Lauren M.; Petigura, Erik; Seager, Sara; Morton, Timothy; Johnson, John Asher; Ballard, Sarah; Burke, Chris; Cochran, William D.; Endl, Michael; MacQueen, Phillip; Everett, Mark E.; Lissauer, Jack J.; Ford, Eric B.; Torres, Guillermo; Fressin, Francois; Brown, Timothy M.; Steffen, Jason H.; Charbonneau, David; Basri, Gibor S.; Sasselov, Dimitar D.; Winn, Joshua; Sanchis-Ojeda, Roberto; Christiansen, Jessie; Adams, Elisabeth; Henze, Christopher; Dupree, Andrea; Fabrycky, Daniel C.; Fortney, Jonathan J.; Tarter, Jill; Holman, Matthew J.; Tenenbaum, Peter; Shporer, Avi; Lucas, Philip W.; Welsh, William F.; Orosz, Jerome A.; Bedding, T. R.; Campante, T. L.; Davies, G. R.; Elsworth, Y.; Handberg, R.; Hekker, S.; Karoff, C.; Kawaler, S. D.; Lund, M. N.; Lundkvist, M.; Metcalfe, T. S.; Miglio, A.; Aguirre, V.; Silva Stello, D.; White, T. R.; Boss, Alan; Devore, Edna; Gould, Alan; Prsa, Andrej; Agol, Eric; Barclay, Thomas; Coughlin, Jeff; Brugamyer, Erik; Mullally, Fergal; Quintana, Elisa V.; Still, Martin; Thompson, Susan E.; Morrison, David; Twicken, Joseph D.; Desert, Jean-Michel; Carter, Josh; Crepp, Justin R.; Hebrard, Guillaume; Santerne, Alexandre; Moutou, Claire; Sobeck, Charlie; Hudgins, Douglas; Haas, Michael R.; Robertson, Paul; Lillo-Box, Jorge; Barrado, David; Cochran, William D.; MacQueen, Phillip J.; Endl, Michael; Robertson, Paul
We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm(-3), suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than similar to 2 R-circle plus. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).
On The Binary Frequency Of The Lowest Mass Members Of The Pleiades With Hubble Space Telescope Wide Field Camera 3
(2015-05) Garcia, E. V.; Dupuy, Trent J.; Allers, Katelyn N.; Liu, Michael C.; Deacon, Niall R.; Dupuy, Trent J.
We present the results of a Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging survey of 11 of the lowest mass brown dwarfs in the Pleiades known (25-40M(Jup)). These objects represent the predecessors to T dwarfs in the field. Using a semi-empirical binary point-spread function (PSF)-fitting technique, we are able to probe to 0 ''.03 (0.75 pixel), better than 2x the WFC3/UVIS diffraction limit. We did not find any companions to our targets. From extensive testing of our PSF-fitting method on simulated binaries, we compute detection limits which rule out companions to our targets with mass ratios of greater than or similar to 0.7 and separations greater than or similar to 4 AU. Thus, our survey is the first to attain the high angular resolution needed to resolve brown dwarf binaries in the Pleiades at separations that are most common in the field population. We constrain the binary frequency over this range of separation and mass ratio of 25-40M(Jup) Pleiades brown dwarfs to be < 11% for 1 sigma (< 26% at 2s). This binary frequency is consistent with both younger and older brown dwarfs in this mass range.
Planet Occurrence within 0.25 AU of Solar-Type Stars from Kepler
(2012-08) Howard, Andrew W.; Marcy, Geoffrey W.; Bryson, Stephen T.; Jenkins, Jon M.; Rowe, Jason F.; Batalha, Natalie M.; Borucki, William J.; Koch, David G.; Dunham, Edward W.; Gautier, Thomas N., III; Van Cleve, Jeffrey; Cochran, William D.; Latham, David W.; Lissauer, Jack J.; Torres, Guillermo; Brown, Timothy M.; Gilliland, Ronald L.; Buchhave, Lars A.; Caldwell, Douglas A.; Christensen-Dalsgaard, Jorgen; Ciardi, David; Fressin, Francois; Haas, Michael R.; Howell, Steve B.; Kjeldsen, Hans; Seager, Sara; Rogers, Leslie; Sasselov, Dimitar D.; Steffen, Jason H.; Basri, Gibor S.; Charbonneau, David; Christiansen, Jessie; Clarke, Bruce; Dupree, Andrea; Fabrycky, Daniel C.; Fischer, Debra A.; Ford, Eric B.; Fortney, Jonathan J.; Tarter, Jill; Girouard, Forrest R.; Holman, Matthew J.; Johnson, John Asher; Klaus, Todd C.; Machalek, Pavel; Moorhead, Althea V.; Morehead, Robert C.; Ragozzine, Darin; Tenenbaum, Peter; Twicken, Joseph D.; Quinn, Samuel N.; Isaacson, Howard; Shporer, Avi; Lucas, Philip W.; Walkowicz, Lucianne M.; Welsh, William F.; Boss, Alan; Devore, Edna; Gould, Alan; Smith, Jeffrey C.; Morris, Robert L.; Prsa, Andrej; Morton, Timothy D.; Still, Martin; Thompson, Susan E.; Mullally, Fergal; Endl, Michael; MacQueen, Phillip J.; Cochran, William D.; Endl, Michael; MacQueen, Phillip J.
We report the distribution of planets as a function of planet radius, orbital period, and stellar effective temperature for orbital periods less than 50 days around solar-type (GK) stars. These results are based on the 1235 planets (formally "planet candidates") from the Kepler mission that include a nearly complete set of detected planets as small as 2 R-circle plus. For each of the 156,000 target stars, we assess the detectability of planets as a function of planet radius, R-p, and orbital period, P, using a measure of the detection efficiency for each star. We also correct for the geometric probability of transit, R-star/a. We consider first Kepler target stars within the "solar subset" having T-eff = 4100-6100 K, log g = 4.0-4.9, and Kepler magnitude Kp < 15 mag, i.e., bright, main-sequence GK stars. We include only those stars having photometric noise low enough to permit detection of planets down to 2 R-circle plus. We count planets in small domains of R-p and P and divide by the included target stars to calculate planet occurrence in each domain. The resulting occurrence of planets varies by more than three orders of magnitude in the radius-orbital period plane and increases substantially down to the smallest radius (2 R-circle plus) and out to the longest orbital period (50 days, similar to 0.25 AU) in our study. For P < 50 days, the distribution of planet radii is given by a power law, df/d log R = k(R)R(alpha) with k(R) = 2.9(-0.4)(+0.5), alpha = -1.92 +/- 0.11, and R equivalent to R-p/R-circle plus. This rapid increase in planet occurrence with decreasing planet size agrees with the prediction of core-accretion Formation but disagrees with population synthesis models that predict a desert at super-Earth and Neptune sizes for close-in orbits. Planets with orbital periods shorter than 2 days are extremely rare; for R-p > 2 R-circle plus we measure an occurrence of less than 0.001 planets per star. For all planets with orbital periods less than 50 days, we measure occurrence of 0.130 +/- 0.008, 0.023 +/- 0.003, and 0.013 +/- 0.002 planets per star for planets with radii 2-4, 4-8, and 8-32 R-circle plus, in agreement with Doppler surveys. We fit occurrence as a function of P to a power-law model with an exponential cutoff below a critical period P-0. For smaller planets, P-0 has larger values, suggesting that the "parking distance" for migrating planets moves outward with decreasing planet size. We also measured planet occurrence over a broader stellar T-eff range of 3600-7100 K, spanning M0 to F2 dwarfs. Over this range, the occurrence of 2-4 R-circle plus planets in the Kepler field increases with decreasing T-eff, with these small planets being seven times more abundant around cool stars (3600-4100 K) than the hottest stars in our sample (6600-7100 K).
Planetary Transit Candidates In The Corot LRa01 Field
(2012-02) Carone, L.; Gandolfi, D.; Cabrera, J.; Hatzes, A. P.; Deeg, H. J.; Csizmadia, S.; Patzold, M.; Weingrill, J.; Aigrain, S.; Alonso, R.; Alapini, A.; Almenara, J. M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Borde, P.; Bouchy, F.; Bruntt, H.; Carpano, S.; Cochran, W. D.; Deleuil, M.; Diaz, R. F.; Dreizler, S.; Dvorak, R.; Eisloffel, J.; Eigmuller, P.; Endl, M.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gazzano, J. C.; Gibson, N.; Gillon, M.; Gondoin, P.; Grziwa, S.; Gunther, E. W.; Guillot, T.; Hartmann, M.; Havel, M.; Hebrard, G.; Jorda, L.; Kabath, P.; Leger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; MacQueen, P. J.; Mayor, M.; Mazeh, T.; Moutou, C.; Nortmann, L.; Ofir, A.; Ollivier, M.; Parviainen, H.; Pepe, F.; Pont, F.; Queloz, D.; Rabus, M.; Rauer, H.; Regulo, C.; Renner, S.; de la Reza, R.; Rouan, D.; Santerne, A.; Samuel, B.; Schneider, J.; Shporer, A.; Stecklum, B.; Tal-Or, L.; Tingley, B.; Udry, S.; Wuchterl, G.; Cochran, W. D.; Endl, M.; MacQueen, P.J.
Context. CoRoT is a pioneering space mission whose primary goals are stellar seismology and extrasolar planets search. Its surveys of large stellar fields generate numerous planetary candidates whose lightcurves have transit-like features. An extensive analytical and observational follow-up effort is undertaken to classify these candidates. Aims. We present the list of planetary transit candidates from the CoRoT LRa01 star field in the Monoceros constellation toward the Galactic anti-center direction. The CoRoT observations of LRa01 lasted from 24 October 2007 to 3 March 2008. Methods. We acquired and analyzed 7470 chromatic and 3938 monochromatic lightcurves. Instrumental noise and stellar variability were treated with several filtering tools by different teams from the CoRoT community. Different transit search algorithms were applied to the lightcurves. Results. Fifty-one stars were classified as planetary transit candidates in LRa01. Thirty-seven (i.e., 73% of all candidates) are >good> planetary candidates based on photometric analysis only. Thirty-two (i.e., 87% of the >good> candidates) have been followed-up. At the time of writing twenty-two cases were solved and five planets were discovered: three transiting hot-Jupiters (CoRoT-5b, CoRoT-12b, and CoRoT-21b), the first terrestrial transiting planet (CoRoT-7b), and another planet in the same system (CoRoT-7c, detected by radial velocity survey only). Evidence of another non-transiting planet in the CoRoT-7 system, namely CoRoT-7d, was recently found as well.
Pulsation Analysis And Its Impact On Primary Transit Modeling In WASP-33
(2014-01) von Essen, C.; Czesla, S.; Wolter, U.; Breger, M.; Herrero, E.; Mallonn, M.; Ribas, I.; Strassmeier, K. G.; Morales, J. C.; Breger, M.
Aims. To date, WASP-33 is the only delta Scuti star known to be orbited by a hot Jupiter. The pronounced stellar pulsations, showing periods comparable to the primary transit duration, interfere with the transit modeling. Therefore our main goal is to study the pulsation spectrum of the host star to redetermine the orbital parameters of the system by means of pulsation-cleaned primary transit light curves. Methods. Between August 2010 and October 2012 we obtained 457 h of photometry of WASP-33 using small and middle-class telescopes located mostly in Spain and in Germany. Our observations comprise the wavelength range between the blue and the red, and provide full phase coverage of the planetary orbit. After a careful detrend, we focus our pulsation studies in the high frequency regime, where the pulsations that mostly deform the primary transit exist. Results. The data allow us to identify, for the first time in the system, eight significant pulsation frequencies. The pulsations are likely associated with low-order p-modes. Furthermore, we find that pulsation phases evolve in time. We use our knowledge of the pulsations to clean the primary transit light curves and carry out an improved transit modeling. Surprisingly, taking into account the pulsations in the modeling has little influence on the derived orbital parameters. However, the uncertainties in the best-fit parameters decrease. Additionally, we find indications for a possible dependence between wavelength and transit depth, but only with marginal significance. A clear pulsation solution, in combination with an accurate orbital period, allows us to extend our studies and search for star-planet interactions (SPI). Although we find no conclusive evidence of SPI, we believe that the pulsation nature of the host star and the proximity between members make WASP-33 a promising system for further SPI studies.
Radial Velocity Observations And Light Curve Noise Modeling Confirm That Kepler-91B Is A Giant Planet Orbiting A Giant Star
(2015-02) Barclay, Thomas; Endl, Michael; Huber, Daniel; Foreman-Mackey, Daniel; Cochran, William D.; MacQueen, Phillip J.; Rowe, Jason F.; Quintana, Elisa V.; Endl, Michael; Cochran, William D.; MacQueen, Phillip J.
Kepler-91b is a rare example of a transiting hot Jupiter around a red giant star, providing the possibility to study the formation and composition of hot Jupiters under different conditions compared to main-sequence stars. However, the planetary nature of Kepler-91b, which was confirmed using phase-curve variations by Lillo-Box et al., was recently called into question based on a re-analysis of Kepler data. We have obtained ground-based radial velocity observations from the Hobby-Eberly Telescope and unambiguously confirm the planetary nature of Kepler-91b by simultaneously modeling the Kepler and radial velocity data. The star exhibits temporally correlated noise due to stellar granulation which we model as a Gaussian Process. We hypothesize that it is this noise component that led previous studies to suspect Kepler-91b to be a false positive. Our work confirms the conclusions presented by Lillo-Box et al. that Kepler-91b is a 0.73 +/- 0.13 M-Jup planet orbiting a red giant star.
Refining The Asteroseismic Model For The Young Delta Scuti Star HD 144277 Using HARPS Spectroscopy
(2014-07) Zwintz, K.; Ryabchikova, T.; Lenz, P.; Pamyatnykh, A. A.; Fossati, L.; Sitnova, T.; Breger, M.; Poretti, E.; Rainer, M.; Hareter, M.; Mantegazza, L.; Breger, M.
Context. HD 144277 was previously discovered by Microvariability and Oscillations of Stars (MOST) space photometry to be a young and hot delta Scuti star showing regular groups of pulsation frequencies. The first asteroseismic models required lower than solar metallicity to fit the observed frequency range based on a purely photometric analysis. Aims. The aim of the present paper is to determine, by means of high-resolution spectroscopy, fundamental stellar parameters required for the asteroseismic model of HD 144277, and subsequently, to refine it. Methods. High-resolution, high signal-to-noise spectroscopic data obtained with the HARPS spectrograph were used to determine the fundamental parameters and chemical abundances of HD 144277. These values were put into context alongside the results from asteroseismic models. Results. The effective temperature, T-eff, of HD 144277 was determined as 8640(-100)(+300) K, log g is 4.14 +/- 0.15 and the projected rotational velocity, v sin i, is 62.0 +/- 2.0 km s(-1). As the v sin i value is significantly larger than previously assumed, we refined the first asteroseimic model accordingly. The overall metallicity Z was determined to be 0.011 where the light elements He, C, O, Na, and S show solar chemical composition, but the heavier elements are significantly underabundant. In addition, the radius of HD 144277 was determined to be 1.55 +/- 0.65 R-circle dot from spectral energy distribution fitting, based on photometric data taken from the literature. Conclusions. From the spectroscopic observations, we could confirm our previous assumption from asteroseismic models that HD 144277 has less than solar metallicity. The fundamental parameters derived from asteroseismology, T-eff, log g, L/L-circle dot and R/R-circle dot agree within one sigma to the values found from spectroscopic analysis. As the v sin i value is significantly higher than assumed in the first analysis, near-degeneracies and rotational mode coupling were taken into account in the new models. These suggest that HD 144277 has an equatorial rotational velocity of about 80 km s(-1) and is seen equator-on. The observed frequencies are identified as prograde modes.