Search Publications

Source region of the 18 November 2003 coronal mass ejection that led to the strongest magnetic storm of cycle 23

Srivastava, Nandita; Mathew, Shibu K.; Louis, Rohan E. +1 more

The superstorm of 20 November 2003 was associated with a high-speed coronal mass ejection (CME) which originated in the NOAA AR 10501 on 18 November. This coronal mass ejection had severe terrestrial consequences leading to a geomagnetic storm with Dst index of -472 nT, the strongest of the current solar cycle. In this paper, we attempt to underst…

Laboratory Spectra of the CO₂ Bending-Mode Feature in Interstellar Ice Analogues Subject to Thermal Processing

Whittet, D. C. B.; Gerakines, P. A.; White, D. W. +1 more

The infrared absorption features of solid carbon dioxide have been detected by space-based observatories in nearly all lines of sight probing the dense interstellar medium (ISM). It has also been shown that the absorption feature of solid CO₂ near 658 cm^-1 (15.2 µm) should be a sensitive indicator of the physical condit…

Metallicity map of the galaxy cluster A3667

Lovisari, L.; Schindler, S.; Ferrari, C. +1 more

We use XMM-Newtondata of the merging cluster Abell 3667 to analyze its metallicity distribution. A detailed abundance map of the central 1.1 × 1.1 Mpc region indicates that metals are inhomogeneously distributed in the cluster showing a non-uniform and very complex metal pattern. The highest peak in the map corresponds to a cold region, slightly o…

HINODE Observations of Coherent Lateral Motion of Penumbral Filaments During an X-Class Flare

Tiwari, Sanjiv Kumar; Venkatakrishnan, P.; Gosain, S.

The X-3.4 class flare of 2006 December 13 was observed with a high cadence of 2 minutes at 0.2 arcsec resolution by HINODE/SOT FG instrument. The flare ribbons could be seen in G-band images also. A careful analysis of these observations after proper registration of images shows flare-related changes in penumbral filaments of the associated sunspo…

Evolution of the X-ray luminosity in young HII galaxies

Nandra, K.; Rosa González, D.; Terlevich, E. +5 more

In an effort to understand the correlation between X-ray emission and present star formation rate, we obtained XMM-Newton data to estimate the X-ray luminosities of a sample of actively star-forming HII galaxies. The obtained X-ray luminosities are compared to other well-known tracers of star formation activity such as the far-infrared and the ult…

Type II Radio Bursts with High and Low Starting Frequencies

Moon, Y. -J.; Shanmugaraju, Annamalai; Vrsnak, Bojan

We report on the detailed analysis of i) differences between the properties of type IIs with various starting frequencies (high: ≥100 MHz; low: ≤50 MHz; mid: 50 MHz ≤f≤ 100 MHz) and ii) the properties of CMEs and flares associated with them. For this study, we considered a sample of type II radio bursts observed by Culgoora radio spectrograph from…

Perturbative reconstruction of a gravitational lens: when mass does not follow light

Alard, C.

Aims: The structure and potential of a complex gravitational lens is reconstructed using the perturbative method presented in Alard (2007, MNRAS, 382, L58; 2008, MNRAS, 388, 375). This lens is composed of 6 galaxies belonging to a small group.
Methods: The lens inversion is reduced to the problem of reconstructing non-degenerate quantities: th…

Sputtering and heating of Titan's upper atmosphere

Johnson, Robert E.

On properties of narrow CMEs observed with SOHO/LASCO

Mittal, Nishant; Narain, Udit; Pandey, Kumud +1 more

We have investigated properties such as speed, angular width, location, acceleration and occurrence rate of narrow CMEs (defined as having angular width ≤20°) observed during 1996–2007 by SOHO/LASCO. The results obtained are compared with those of normal CMEs (angular width >20°) from the same time interval to find whether there are any real di…

The Magellanic Bridge as a Damped Lyman Alpha System: Physical Properties of Cold Gas Toward PKS 0312-770

Kobulnicky, Henry A.; Charlton, Jane C.; Bland-Hawthorn, Joss +2 more

We measure the physical properties of a local multicomponent absorption-line system at V _sun ~200 km s^-1 toward the quasar PKS 0312-770 behind the Magellanic Bridge (MB) using Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) spectroscopy in conjunction with photoionization modeling. At an impact parameter of…