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- Osborn, H. P., et al.
(författare)
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The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 485:2, s. 1614-1625
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Tidskriftsartikel (refereegranskat)abstract
- PDS 110 is a young disc-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper, we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in 2017 September. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for radial velocity (RV) oscillations caused by any hypothetical companion and can rule out close binaries to 0.1Ms. Asearch of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 yr, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and of shorter duration than those of UX Ori variables, but may have a similar mechanism.
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| 4. |
- Mancini, L., et al.
(författare)
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The GAPS programme with HARPS-N at TNG XVI. Measurement of the Rossiter-McLaughlin effect of transiting planetary systems HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 613
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Tidskriftsartikel (refereegranskat)abstract
- Context. The measurement of the orbital obliquity of hot Jupiters with different physical characteristics can provide clues to the mechanisms of migration and orbital evolution of this particular class of giant exoplanets.Aims. We aim to derive the degree of alignment between planetary orbit and stellar spin angular momentum vectors and look for possible links with other orbital and fundamental physical parameters of the star-planet system. We focus on the characterisation of five transiting planetary systems (HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60) and the determination of their sky-projected planet orbital obliquity through the measurement of the Rossiter-McLaughlin effect.Methods. We used HARPS-N high-precision radial velocity measurements, gathered during transit events, to measure the Rossiter-McLaughlin effect in the target systems and determine the sky-projected angle between the planetary orbital plane and stellar equator. The characterisation of stellar atmospheric parameters was performed by exploiting the HARPS-N spectra, using line equivalent width ratios and spectral synthesis methods. Photometric parameters of the five transiting exoplanets were re-analysed through 17 new light curves, obtained with an array of medium-class telescopes, and other light curves from the literature. Survey-time-series photometric data were analysed for determining the rotation periods of the five stars and their spin inclination.Results. From the analysis of the Rossiter-McLaughlin effect we derived a sky-projected obliquity of lambda = 21.2 degrees +/- 8.7 degrees, lambda = -54 degrees(+41 degrees)(-13 degrees), lambda = -2.1 degrees +/- 3.0 degrees, lambda = 0 degrees +/- 11 degrees, and lambda = -129 degrees +/- 17 degrees for HAT-P-3 b, HAT-P-12 b, HAT-P-22 b, WASP-39 b, and WASP-60 b, respectively. The latter value indicates that WASP-60 b is moving on a retrograde orbit. These values represent the first measurements of lambda for the five exoplanetary systems under study. The stellar activity of HAT-P-22 indicates a rotation period of 28.7 +/- 0.4 days, which allowed us to estimate the true misalignment angle of HAT-P-22 b, psi = 24 degrees +/- 18 degrees. The revision of the physical parameters of the five exoplanetary systems returned values that are fully compatible with those existing in the literature. The exception to this is the WASP-60 system, for which, based on higher quality spectroscopic and photometric data, we found a more massive and younger star and a larger and hotter planet.
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| 5. |
- Ryu, Y. -H., et al.
(författare)
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OGLE-2016-BLG-1190Lb : The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary
- 2018
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 155:1
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/ bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M-p = 13.4 +/- 0.9 M-J, places it right at the deuteriumburning limit, i. e., the conventional boundary between planets and brown dwarfs. Its existence raises the question of whether such objects are really planets (formed within the disks of their hosts) or failed stars (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M-host = 0.89. +/- 0.07 M-circle dot, and the planet has a semimajor axis a similar to 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over < 1% of an orbital period.
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- Alsubai, Khalid, et al.
(författare)
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Qatar Exoplanet Survey : Qatar-3b, Qatar-4b, and Qatar-5b
- 2017
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 153:4
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey. 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 +/- 0.47 M-J, M-Q4b = 6.10 +/- 0.54 M-J, and M-Q5b = 4.32 +/- 0.18 M-J, while model fits to the transit light curves yield radii of R-Q3b = 1.096 +/- 0.14 RJ, R-Q4b = 1.135 +/- 0.11 R-J, and R-Q5b = 1.107 +/- 0.064 R-J. The host stars are low-mass main sequence stars with masses and radii M-Q3 = 1.145 +/- 0.064 M circle dot, M-Q4 = 0.896 +/- 0.048 M circle dot, M-Q5 = 1.128 +/- 0.056 M circle dot and R-Q3 = 1.272 +/- 0.14 R circle dot, R-Q4 = 0.849 +/- 0.063 R circle dot, and R-Q5 = 1.076 +/- 0.051 R circle dot 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).
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