Search Publications
BRITE-Constellation photometry of π5 Orionis, an ellipsoidal SPB variable
Handler, G.; Wade, G. A.; Pigulski, A. +5 more
Results of an analysis of the BRITE-Constellation photometry of the SB1 system and ellipsoidal variable π5 Ori (B2 III) are presented. In addition to the orbital light-variation, which can be represented as a five-term Fourier cosine series with the frequencies forb, 2forb, 3forb, 4forb, and 6…
Stellar coronal X-ray emission and surface magnetic flux
Peter, H.; Zhuleku, J.; Warnecke, J.
Context. Observations show that the coronal X-ray emission of the Sun and other stars depends on the surface magnetic field.
Aims: Using power-law scaling relations between different physical parameters, we aim to build an analytical model to connect the observed X-ray emission to the surface magnetic flux.
Methods: The basis for our mod…
The NGC 346 massive star census. Nitrogen abundances for apparently single, narrow lined, hydrogen core burning B-type stars
Dufton, P. L.; Lennon, D. J.; Evans, C. J. +1 more
Previous analyses of two large spectroscopic surveys of early-type stars in the Large Magellanic Cloud (LMC) have found an excess of nitrogen enriched B-type targets with a ve sin i ≤ 40 km s-1 compared with the predictions of single star evolutionary models that incorporate rotational mixing. By contrast, the number of such …
Low-activity Main-belt Comet 133P/Elst-Pizarro: New Constraints on Its Albedo, Temperature, and Active Mechanism from a Thermophysical Perspective
Ip, Wing-Huen; Hsia, Chih Hao; Yu, Liang Liang
133P/Elst-Pizarro is the first recognized main-belt comet, but we still know little about its nucleus. First we use mid-infrared data of Spitzer MIPS, Spitzer IRS, and the Wide-field Infrared Survey Explorer to estimate its effective diameter, ${D}_{\mathrm{eff}}={3.9}_{-0.3}^{+0.4}$ km, geometric albedo, ${p}_{{\rm{v}}}=0.074\pm 0.013$ , and mean…
Fermi-LAT Observations of V549 Vel 2017: A Subluminous Gamma-Ray Nova?
Strader, Jay; Chomiuk, Laura; Munari, Ulisse +4 more
We report on the Fermi Large Area Telescope detection (with ≈5.7σ significance) as well as the multiwavelength analysis of the 2017 nova eruption V549 Vel. Unlike the recent shock-powered novae ASASSN-16ma and V906 Car, the optical and γ-ray light curves of V549 Vel show no correlation, likely implying relatively weak shocks in the eruption. Gaia …
The Star Formation Rate-Radius Connection: Data and Implications for Wind Strength and Halo Concentration
Barro, Guillermo; Ferguson, Henry C.; Grogin, Norman A. +26 more
This paper is one in a series that explores the importance of radius as a second parameter in galaxy evolution. The topic investigated here is the relationship between star formation rate (SFR) and galaxy radius ( ${R}_{{\rm{e}}}$ ) for main-sequence star-forming galaxies. The key observational result is that, over a wide range of stellar mass and…
Spectro-imaging forward model of red and blue galaxies
Tortorelli, Luca; Herbel, Jörg; Amara, Adam +3 more
For the next generation of spectroscopic galaxy surveys, it is important to forecast their performances and to accurately interpret their large data sets. For this purpose, it is necessary to consistently simulate different populations of galaxies, in particular Emission Line Galaxies (ELGs), less used in the past for cosmological purposes. In thi…
Low Geo-Effectiveness of Fast Halo CMEs Related to the 12 X-Class Flares in 2002
Bocchialini, K.; Schmieder, B.; Poedts, S. +4 more
It is generally accepted that extreme space weather events tend to be related to strong flares and fast halo coronal mass ejections (CMEs). In the present paper, we carefully identify the chain of events from the Sun to the Earth induced by all 12 X-class flares that occurred in 2002. In this small sample, we find an unusual high rate (58%) of sol…
More than softer-when-brighter: The X-ray powerlaw spectral variability in NGC 4051
Cai, Zheng; Kang, Jia-Lai; Cai, Zhen-Yi +3 more
The powerlaw X-ray spectra of active galactic nuclei at moderate to high accretion rates normally appear softer when they brighten, for which the underlying mechanisms are yet unclear. Utilizing XMM-Newton observations and excluding photons < 2 keV to avoid contamination from the soft excess, in this work we scrutinize the powerlaw spectral var…
Relating grain size distributions in circumstellar discs to the spectral index at millimetre wavelengths
Löhne, T.
The excess emission seen in spectral energy distributions (SEDs) is commonly used to infer the properties of the emitting circumstellar dust in protoplanetary and debris discs. Most notably, dust size distributions and details of the collision physics are derived from SED slopes at long wavelengths. This paper reviews the approximations that are c…