A K2 target exhibits 28 non-periodic transit-like events with no more than four consistent with any periodic orbit, passing basic data-quality checks but unexplained by conventional transit or activity models.
Gaia Data Release 2: The astrometric solution
5 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
Gaia Data Release 2 (Gaia DR2) contains results for 1693 million sources in the magnitude range 3 to 21 based on observations collected by the European Space Agency Gaia satellite during the first 22 months of its operational phase. We describe the input data, models, and processing used for the astrometric content of Gaia DR2, and the validation of these results performed within the astrometry task. Some 320 billion centroid positions from the pre-processed astrometric CCD observations were used to estimate the five astrometric parameters (positions, parallaxes, and proper motions) for 1332 million sources, and approximate positions at the reference epoch J2015.5 for an additional 361 million mostly faint sources. Special validation solutions were used to characterise the random and systematic errors in parallax and proper motion. For the sources with five-parameter astrometric solutions, the median uncertainty in parallax and position at the reference epoch J2015.5 is about 0.04 mas for bright (G<14 mag) sources, 0.1 mas at G=17 mag, and 0.7 mas at G=20 mag. In the proper motion components the corresponding uncertainties are 0.05, 0.2, and 1.2 mas/yr, respectively. The optical reference frame defined by Gaia DR2 is aligned with ICRS and is non-rotating with respect to the quasars to within 0.15 mas/yr. From the quasars and validation solutions we estimate that systematics in the parallaxes depending on position, magnitude, and colour are generally below 0.1 mas, but the parallaxes are on the whole too small by about 0.03 mas. Significant spatial correlations of up to 0.04 mas in parallax and 0.07 mas/yr in proper motion are seen on small (<1 deg) and intermediate (20 deg) angular scales. Important statistics and information for the users of the Gaia DR2 astrometry are given in the appendices.
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citing papers explorer
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The Random Transiter -- EPIC 249706694/HD 139139
A K2 target exhibits 28 non-periodic transit-like events with no more than four consistent with any periodic orbit, passing basic data-quality checks but unexplained by conventional transit or activity models.
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Exoplanets in ancient stellar populations: occurrence constraints and hot-Jupiter candidates in the Galactic halo
Hot Jupiter occurrence in the Galactic halo is low at ~0.13% with no significant difference between in-situ and accreted populations, well below disk rates.
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Solving the distance discrepancy for the open cluster NGC 2453. The planetary nebula NGC 2452 is not a cluster member
NGC 2453 cluster distance is 4.7 kpc with age 40-50 Myr; planetary nebula NGC 2452 is a non-member foreground object.
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The Arecibo telescope advanced radio astronomy via serendipitous discoveries and successive upgrades to its reflector, optics, receivers, and data systems over its operational lifetime.
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Astronomical distance scales in the Gaia era
Overview of astronomical distance scales from solar system to extragalactic, emphasizing trigonometric stellar distances and advances from Hipparcos and Gaia.