Search Publications
Constraints to the magnetospheric properties of T Tauri stars - I. The C II], Fe II] and Si II] ultraviolet features
López-Martínez, Fatima; Gómez de Castro, Ana Inés
The C II] feature at ∼2325 Å is very prominent in the spectra of T Tauri stars (TTSs). This feature is a quintuplet of semiforbidden transitions excited at electron temperatures around 10 000 K that, together with the nearby Si II] and Fe II] features, provides a reliable optically thin tracer for accurate measurement of the plasma properties in t…
Observations of umbral dots and their physical models
Watanabe, Hiroko
The Hinode satellite opens a new era in sunspot research, because of its high spatial resolution and temporal stability. Fine-scale structures in sunspots, called umbral dots (UDs), have become one of the hottest topics in terms of close observations of magnetoconvection. In this paper, a brief review of the observed properties of UDs is given bas…
The role of major mergers in the size growth of intermediate-mass spheroids
Ryan, R. E.; O'Connell, R. W.; Koekemoer, A. M. +11 more
We study of the role of `major' mergers (mass ratios >1: 4) in driving size growth in high-redshift (1 < z < 2) spheroidal galaxies (SGs) with stellar masses between 109.5 and 1010.7 M⊙. This is a largely unexplored mass range at this epoch, containing the progenitors of more massive SGs on which the bulk …
Panchromatic Hubble Andromeda Treasury. IX. A Photometric Survey of Planetary Nebulae in M31
Williams, Benjamin F.; Gordon, Karl D.; Caldwell, Nelson +8 more
We search the Hubble Space Telescope (HST) Advanced Camera for Surveys and Wide Field Camera 3 broadband imaging data from the Panchromatic Hubble Andromeda Treasury (PHAT) survey to identify detections of cataloged planetary nebulae (PNs). Of the 711 PNs currently in the literature within the PHAT footprint, we find 467 detected in the broadband.…
Carbon dioxide absorption at high densities in the 1.18 µm nightside transparency window of Venus
Piccioni, Giuseppe; Snels, Marcel; Stefani, Stefania +1 more
The attenuation of carbon dioxide at pressures between 1 and 38 bar has been measured from 1179.5 to 1182.7 nm at room temperature (293 K) by using a cavity ring down spectrometer. The densities used in the experiment correspond with the densities in the Venus atmosphere from about 50 km down to the surface, although the experimental temperature i…
Magnitude-range brightness variations of overactive K giants
Strassmeier, K. G.; Granzer, T.; Kriskovics, L. +4 more
Context. Decades-long, phase-resolved photometry of overactive spotted cool stars has revealed that their long-term peak-to-peak light variations can be as large as one magnitude. Such brightness variations are too large to be solely explained by rotational modulation and/or a cyclic, or pseudo-cyclic, waxing and waning of surface spots and facula…
Fractal and Multifractal Properties of Active Regions as Flare Precursors: A Case Study Based on SOHO/MDI and SDO/HMI Observations
Romano, P.; Zuccarello, F.; Ermolli, I. +3 more
Several studies indicate that fractal and multifractal parameters inferred from solar photospheric magnetic field measurements may help assessing the eruptive potential of Active Regions (ARs) and also predicting their flare activity. We further investigate this topic, by exploring the sensitivity of some parameters already used in the literature …
Spitzer IRS Observations of the XA Region in the Cygnus Loop Supernova Remnant
Blair, William P.; Raymond, John C.; Borkowski, Kazimierz J. +5 more
We report on spectra of two positions in the XA region of the Cygnus Loop supernova remnant obtained with the InfraRed Spectrograph on the Spitzer Space Telescope. The spectra span the 10-35 µm wavelength range, which contains a number of collisionally excited forbidden lines. These data are supplemented by optical spectra obtained at the Wh…
Emission mechanism of GeV-quiet soft gamma-ray pulsars: a case for peculiar geometry?
Leung, Gene C. K.; Cheng, K. S.; Takata, J. +2 more
There is a growing new class of young spin-down powered pulsars called GeV-quiet soft gamma-ray pulsar; (1) spectral turnover appears around 10 MeV, (2) the X-ray spectra of below 20 keV can be described by power law with a photon index of around 1.2 and (3) the light curve in X-ray/soft gamma-ray bands shows single broad pulse. Their emission pro…
Multiwavelength campaign on Mrk 509. XIV. Chandra HETGS spectra
Kaastra, J. S.; Kriss, G. A.; Arav, N. +14 more
Context. We present in this paper the results of a 270 ks Chandra HETGS observation in the context of a large multiwavelength campaign on the Seyfert galaxy Mrk 509.
Aims: The HETGS spectrum allows us to study the high ionisation warm absorber and the Fe-K complex in Mrk 509. We search for variability in the spectral properties of the source …