Search Publications
Detection of HF emission from the Orion Bar
Ossenkopf, V.; Nagy, Z.; Bergin, E. A. +3 more
Context. The clumpy density structure of photon-dominated regions is well established, but the physical properties of the clumps and of the surrounding interclump medium are only approximately known.
Aims: The aim of this paper is to constrain the physical and chemical conditions in the Orion Bar, a prototypical nearby photon-dominated region…
Impact of the rippling of a perpendicular shock front on ion dynamics
Lembège, B.; Lu, Q. M.; Yang, Z. W.
Both hybrid/full particle simulations and recent experimental results have clearly evidenced that the front of a supercritical quasi-perpendicular shock can be rippled. Recent two-dimensional simulations have focused on two different types of shock front rippling: (1) one characterized by a small spatial scale along the front is supported by lower…
Prior Flaring as a Complement to Free Magnetic Energy for Forecasting Solar Eruptions
Moore, Ronald L.; Falconer, David A.; Barghouty, Abdulnasser F. +1 more
From a large database of (1) 40,000 SOHO/MDI line-of-sight magnetograms covering the passage of 1300 sunspot active regions across the 30° radius central disk of the Sun, (2) a proxy of each active region's free magnetic energy measured from each of the active region's central-disk-passage magnetograms, and (3) each active region's full-disk-passa…
Rebirth of X-Ray Emission from the Born-again Planetary Nebula A30
Steffen, M.; Gruendl, R. A.; Hamann, W. -R. +8 more
The planetary nebula A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using multi-epoch Hubble Space Telescope images, we have detected the angular expansion of these knots and derived an age of 850+280 - 150 yr. To investigate the spectral and spatial p…
The Cold Shoulder: Emission Measure Distributions of Active Region Cores
Schmelz, J. T.; Pathak, S.
The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the "inter-moss" areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission …
Superorbital Modulation of X-Ray Emission from Gamma-Ray Binary LSI +61 303
Lutovinov, A.; Molkov, S.; Chernyakova, M. +3 more
We report the discovery of a systematic constant time lag between the X-ray and radio flares of the gamma-ray binary LSI +61 303, persistent over a long, multi-year timescale. Using the data from the monitoring of the system by RXTE we show that the orbital phase of X-ray flares from the source varies from phi X ~= 0.35 to phi X <…
Recurrent dust formation by WR 48a on a 30-year time-scale
Marang, Fred; Whitelock, Patricia A.; Williams, Peredur M. +4 more
We present infrared photometry of the WC8 Wolf-Rayet system WR 48a observed with telescopes at the European Southern Observatory, the South African Astronomical Observatory and the Anglo Australian Telescope between 1982 and 2011, which show a slow decline in dust emission from the previously reported outburst in 1978-79 until about 1997, when sig…
Revealing Companions to Nearby Stars with Astrometric Acceleration
Tokovinin, Andrei; Makarov, Valeri V.; Hayward, Thomas L. +1 more
A subset of 51 Hipparcos astrometric binaries among FG dwarfs within 67 pc has been surveyed with the Near-Infrared Coronagraphic Imager adaptive optics system at Gemini-S, directly resolving for the first time 17 subarcsecond companions and 7 wider ones. Using these data together with published speckle interferometry of 57 stars, we compare the s…
Ammonia and other parent molecules in comet 10P/Tempel 2 from Herschel/HIFI and ground-based radio observations
Küppers, M.; Hartogh, P.; Crovisier, J. +12 more
The Jupiter-family comet 10P/Tempel 2 was observed during its 2010 return with the Herschel Space Observatory. We present here the observation of the JK (10-00) transition of NH3 at 572 GHz in this comet with the Heterodyne Instrument for the Far Infrared (HIFI) of Herschel. We also report on radio obser…
Quantifying the universality of the stellar initial mass function in old star clusters
Sills, Alison; Sarajedini, Ata; de Marchi, Guido +4 more
We present a new technique to quantify cluster-to-cluster variations in the observed present-day stellar mass functions of a large sample of star clusters. Our method quantifies these differences as a function of both the stellar mass and the total cluster mass, and offers the advantage that it is insensitive to the precise functional form of the …