Search Publications
Asteroid thermal modeling in the presence of reflected sunlight
Myhrvold, Nathan
A new derivation of simple asteroid thermal models is presented, investigating the need to account correctly for Kirchhoff's law of thermal radiation when IR observations contain substantial reflected sunlight. The framework applies to both the NEATM and related thermal models. A new parameterization of these models eliminates the dependence of th…
Three-dimensional dust mapping in the Orion complex, combining Gaia-TGAS, 2MASS, and WISE
Bailer-Jones, C. A. L.; Fouesneau, M.; Schlafly, E. F. +1 more
We present a map of the three-dimensional (3D) distribution of dust in the Orion complex. Orion is the closest site of high-mass star formation, making it an excellent laboratory for studying the interstellar medium and star formation. We used data from the Gaia-TGAS catalogue combined with photometry from 2MASS and WISE to get the distances and e…
O+ Escape During the Extreme Space Weather Event of 4-10 September 2017
Nilsson, Hans; Dandouras, Iannis; Slapak, Rikard +5 more
We have investigated the consequences of extreme space weather on ion outflow from the polar ionosphere by analyzing the solar storm that occurred early September 2017, causing a severe geomagnetic storm. Several X-flares and coronal mass ejections were observed between 4 and 10 September. The first shock—likely associated with a coronal mass ejec…
Resolving the X-Ray Obscuration in a Low-flux Observation of the Quasar PDS 456
Turner, T. J.; O'Brien, P. T.; Reeves, J. N. +5 more
Simultaneous XMM-Newton, NuSTAR, and HST observations, performed in 2017 March, of the nearby (z = 0.184) luminous quasar PDS 456 are presented. PDS 456 had a low X-ray flux compared to past observations, where the first of the two new XMM-Newton observations occurred during a pronounced dip in the X-ray light curve. The broadband X-ray spectrum i…
A quantitative NLTE analysis of visual and ultraviolet spectra of four helium-rich subdwarf O stars
Heber, U.; Latour, M.; Irrgang, A. +4 more
Aims: Hot subdwarf stars represent a poorly understood late phase of stellar evolution. While binary evolution plays an important role for the formation of B-type subdwarfs (sdB), the origin of the helium dominated subclass of O-type subdwarfs (He-sdO) is still unknown. We search for chemical signatures of their genesis by means of quantitati…
A simultaneous spectroscopic and photometric study of two eclipsing binaries: V566 Oph and V972 Her
Yılmaz, M.; Selam, S. O.; Esmer, E. M. +4 more
In this study, we have performed simultaneous solutions of light and radial velocity curves of two eclipsing binary systems, V566 Oph and V972 Her. We observed both systems spectroscopically with a very recently installed spectrograph on the 40 cm telescope, T40, located in Ankara University Kreiken Observatory (AUKR), for the first time. We made …
The near-nucleus gas coma of comet 67P/Churyumov-Gerasimenko prior to the descent of the surface lander PHILAE
Altwegg, K.; Rubin, M.; Zakharov, V. V. +2 more
Context. The European Space Agency (ESA) Rosetta mission was the most comprehensive study of a comet ever performed. In particular, the Rosetta orbiter, which carried many instruments for monitoring the evolution of the dusty gas emitted by the cometary nucleus, returned an enormous volume of observational data collected from the close vicinity of…
Simultaneous Spectral Energy Distribution and Near-infrared Interferometry Modeling of HD 142666
Monnier, John D.; Kraus, Stefan; Baron, Fabien +10 more
We present comprehensive models of the Herbig Ae star, HD 142666, which aim to simultaneously explain its spectral energy distribution (SED) and near-infrared (NIR) interferometry. Our new submilliarcsecond resolution CHARA (CLASSIC and CLIMB) interferometric observations, supplemented with archival shorter baseline data from VLTI/PIONIER and the …
Are Starspots and Plages Co-located on Active G and K Stars?
Hawley, Suzanne L.; Agol, Eric; Agüeros, Marcel A. +4 more
We explore the connection between starspots and plages of three main-sequence stars by studying the chromospheric and photospheric activity over several rotation periods. We present simultaneous photometry and high-resolution (R ∼ 31500) spectroscopy of KIC 9652680, a young, super-flare-producing G1 star with a rotation period of 1.4 days. Its Kep…
Intensity-corrected Herschel Observations of Nearby Isolated Low-mass Clouds
Bourke, Tyler L.; Di Francesco, James; Myers, Philip C. +8 more
We present intensity-corrected Herschel maps at 100, 160, 250, 350, and 500 µm for 56 isolated low-mass clouds. We determine the zero-point corrections for Herschel Photodetector Array Camera and Spectrometer (PACS) and Spectral Photometric Imaging Receiver (SPIRE) maps from the Herschel Science Archive (HSA) using Planck data. Since these H…