Search Publications
Joint XMM-Newton and NuSTAR observations of the reflection spectrum of III Zw 2
Savolainen, Tuomas; Chamani, Wara; Koljonen, Karri
Detecting and modeling the reprocessed hard X-ray emission component in the accretion flow, the so-called reflection spectrum, is a main tool used to estimate black hole spins in a wide range of astrophysical black holes, regardless of their mass or distance. In this work, we study the X-ray spectra of the Seyfert I galaxy III Zw 2 by using multie…
Mapping Circumstellar Magnetic Fields of Late-type Evolved Stars with the Goldreich-Kylafis Effect: CARMA Observations at λ1.3 mm of R Crt and R Leo
Lai, Shih-Ping; Agudo, Iván; Vlemmings, Wouter H. T. +3 more
Mapping magnetic fields is the key to resolving the unclear physical picture of circumstellar magnetic fields in late-type evolved stars. Observations of linearly polarized emission from thermal molecular line transitions due to the Goldreich-Kylafis (G-K) effect provide valuable insights into the magnetic field geometry in these sources that are …
Investigation of contact binaries in the field of NGC 6811
Liu, Liang; Li, Xu-Zhi; Zhang, Xu-Dong
Contact binary systems are very important for studying physical processes such as strong interactions between stars, mass transfer, and stellar merger. Further, the members of an open cluster have the same age, metal abundance, and interstellar extinction conditions. Therefore, we can conduct a comparative study on the different binary systems of …
The Bubble Nebula NGC 7635 - testing the wind-blown bubble theory
Chu, Y. -H.; Guerrero, M. A.; Toalá, J. A. +5 more
We present a multiwavelength study of the iconic Bubble Nebula (NGC 7635) and its ionizing star BD+60○2522. We obtained XMM-Newton EPIC X-ray observations to search for extended X-ray emission as in other similar wind-blown bubbles around massive stars. We also obtained San Pedro Mártir spectroscopic observations with the Manchester Ech…
Stellar laboratories. X. New Cu IV-VII oscillator strengths and the first detection of copper and indium in hot white dwarfs
Rauch, T.; Werner, K.; Kruk, J. W. +4 more
Context. Accurate atomic data is an essential ingredient for the calculation of reliable non-local thermodynamic equilibrium (NLTE) model atmospheres that are mandatory for the spectral analysis of hot stars.
Aims: We aim to search for and identify for the first time spectral lines of copper (atomic number Z = 29) and indium (Z = 49) in hot w…
Switches between accretion structures during flares in 4U 1901+03
Tsygankov, S.; Santangelo, A.; Zhang, Yi +125 more
We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the f…
Proxima Centauri - the nearest planet host observed simultaneously with AstroSat, Chandra, and HST
Schmitt, J. H. M. M.; Burwitz, V.; Loyd, R. O. Parke +6 more
Our nearest stellar neighbour, Proxima Centauri, is a low-mass star with spectral type dM5.5 and hosting an Earth-like planet orbiting within its habitable zone. However, the habitability of the planet depends on the high-energy radiation of the chromospheric and coronal activity of the host star. We report the AstroSat, Chandra, and HST observati…
Connecting the Wilson depression to the magnetic field of sunspots
Solanki, S. K.; Lagg, A.; Löptien, B. +1 more
Context. In sunspots, the geometric height of continuum optical depth unity is depressed compared to the quiet Sun. This so-called Wilson depression is caused by the Lorentz force of the strong magnetic field inside the spots. However, it is not understood in detail yet how the Wilson depression is related to the strength and geometry of the magne…
An elliptic expansion of the potential field source surface model
Wimmer-Schweingruber, R. F.; Kruse, M.; Heidrich-Meisner, V. +1 more
Context. The potential field source surface model is frequently used as a basis for further scientific investigations where a comprehensive coronal magnetic field is of importance. Its parameters, especially the position and shape of the source surface, are crucial for the interpretation of the state of the interplanetary medium. Improvements have…
Identification of Single Spectral Lines through Supervised Machine Learning in a Large HST Survey (WISP): A Pilot Study for Euclid and WFIRST
Rodighiero, G.; Malkan, M.; Henry, A. +13 more
Future surveys focusing on understanding the nature of dark energy (e.g., Euclid and WFIRST) will cover large fractions of the extragalactic sky in near-IR slitless spectroscopy. These surveys will detect a large number of galaxies that will have only one emission line in the covered spectral range. In order to maximize the scientific return of th…