Carina Nebula with XMM-Newton
This document is a black and white copy of an XMM-Newton picture of the Carina Nebula.
Hamaguchi, K.↗
Engineering topics
Hamaguchi, K.
Publications and source records attributed to Hamaguchi, K..
Dynamics of the Shocked Gas in the Eta Carinae System as Seen by Chandra
We report on a series of X-ray spectra of the supermassive star Eta Carinae obtained by the High Energy Transmission Grating Spectrometer on the CHANDRA X-ray observatory before, during and after the star's X-ray minimum in the summer of 2003. The X-ray spectra show significant variations in emission measure and absorption, in the strength of the iron K edge and fluorescent iron emission, but show little change in the distribution of emission measure with temperature. The CHANDRA spectra also resolve emission from Si, S, Fe and other elements in H-like and He-like configurations. The HETGS spectra show that these lines change in centroid energy along with evidence of changes in the forbidden-to-intercombination ratios of the He-like triplets. These spectra offer strong support that the X-ray emission originates within a shock cone around an unseen, massive companion. The variations of the X-ray line spectrum provide a direct measure of the dynamics of the shocked gas in this cone and also evidence that the hottest region of the shock is not always in collisional ionization equilibrium. We discuss these results in light of the recent discovery of He II 4686 emission and the reported discovery of FUV emission from the companion star. This work was supported by SAO/Chandra grant GO3-4008A.
Corcoran, M. F.↗
Global X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum
We report on the results of the X-ray observing campaign of the massive, evolved star Eta Carinae in 2003 around its recent X-ray Minimum, mainly using data from the XMM-Newton observatory. These imaging observations show that the hard X-ray source associated with the Eta Carinae system does not completely disappear in any of the observations during the Minimum. The variation of the spectral shape revealed two emission components. One newly discovered component did not exhibit any variation on kilo-second to year-long timescales, in a combined analysis with earlier ASCA and ROSAT data, and might represent the collision of a high speed outflow from Eta Carinae with ambient gas clouds. The other emission component was strongly variable in flux but the temperature of the hottest plasma did not vary significantly at any orbital phase. Absorption to the hard emission, was about a factor of three larger than the absorption determined from the cutoff of the soft emission, and reached a maximum of approx.4 x 10(exp 23)/sq cm before the Minimum. The thermal Fe\rm XXV emission line showed significant excesses on both the red and blue sides of the line outside the Minimum and exhibited a large redward excess during the Minimum. This variation in the line profile probably requires an abrupt change in ionization balance in the shocked gas.
Hamaguchi, K.↗
Waiting in the Wings: Reflected X-ray Emission from the Homunculus Nebula
We report the first detection of X-ray emission associated with the Homunculus Nebula which surrounds the supermassive star eta Carinae. The emission is characterized by a temperature in excess of 100 MK, and is consistent with scattering of the time-delayed X-ray flux associated with the star. The nebular emission is bright in the northwestern lobe and near the central regions of the Homunculus, and fainter in the southeastern lobe. We also report the detection of an unusually broad Fe K fluorescent line, which may indicate fluorescent scattering off the wind of a companion star or some other high velocity outflow. The X-ray Homunculus is the nearest member of the small class of Galactic X-ray reflection nebulae, and the only one in which both the emitting and reflecting sources are distinguishable.
Corcoran, M. F.↗
High Resolution Temporal and Spectral Monitoring of Eta Carinae's X-Ray Emission the June Eclipse
The supermassive and luminous star Eta Carinae undergoes strong X-ray variations every 5.5 years when its 2-10 keV X-ray emission brightens rapidly with wild fluctuations before dropping by a factor of 100 to a minimum lasting 3 months. The most recent X-ray "eclipse" began in June 2003 and during this time Eta Carinae was intensely observed throughout the electromagnetic spectrum. Here we report the first results of frequent monitoring of the 2-10 keV band X-ray emission by the Rossi X-ray Timing Explorer along wit high resolution X-ray spectra obtained with the transmission gratings on the Chandra X-ray Observatory. We compare these observations to those results obtained during the previous X-ray eclipse in 1998, and interpret the variations in the X-ray brightness, in the amount of absorption, in the X-ray emission measure and in the K-shell emission lines in terms of a colliding wind binary model.
Corcoran, M. F.↗
XMM-Newton Observations of the 2003 X-Ray Minimum of Eta Carinae
The XMM-Newton X-ray observatory took part in the multi-wavelength observing campaign of the massive, evolved star Eta Carinae in 2003 during its recent X-ray minimum in June 2003. This paper reports on the first results of these observations, which were performed (1) before the minimum (five times in January, 2003), (2) near the X-ray maximum just before the minimum (two times in June) and (3) during the minimum (four times in July-August). Hard X-ray emission from the point source of Eta Carinae was detected even during the minimum. The observed flux above 3 keV was approx. 3x10(exp -12) ergs cm(exp -2)/s, which is about one percent of the flux before the minimum. Light curves from the individual observations show no time variability on the scale of a few kilo-seconds. Changes in the spectral shape occurred, but these changes were smaller than expected if the minimum is produced solely by an increase of hydrogen column density. Fits of the hard X-Ray source by an absorbed 1T model show a constant plasma temperature at around 5 keV and an increase of column density from 5x10(exp 22) cm(exp -2) to 2x10(exp 23) cm(exp -2). The spectra below 6 keV significantly deviate from the models that fit the higher energy emission. The X-ray minimum seems to be dominated by an apparent decrease of the emission measure, suggesting that the brightest part of the X-ray emitting region is completely obscured during the minimum in the form of an eclipse. Partial covering plasma emission models might be considered for the spectral variation. The spectra also showed strong iron K line emission from both hot and cold gases, and weak line emission from Ni, Ca, Ar, S and Si.
Hamaguchi, K.↗
Suzaku Reveals He-burning Products in the X-ray Emitting Planetary Nebula BD +30deg 3639
BD +30deg 3639, the brightest planetary nebula at X-ray energies, was observed with Suzaku, an X-ray observatory launched on 2005 July 10. Using the X-ray Imaging Spectrometer, the K-lines from C VI, O VII, and O VIII were resolved for the first time, and C/O, N/O, and Ne/O abundance ratios determined. The C/O abundance ratio exceeds the solar value by nearly two orders of magnitude, and that of Ne/O by at least a factor of 5. These results indicate that the X-rays are emitted mainly by helium shell-burning products.
Murashima, M.↗
Heat Transfer Characteristics of Regenerator Matrix (Case of Packed Wire Gauzes)
The average heat transfer coefficient in the matrix of laminated wire screens (10 to 250 mesh) for a Stirling engine heat exchanger was studied experimentally. The data are correlated by N sub ud = 0.42 R sub ed 0.56 (3 or = R sub ed or = 400), and R sub ed are the Nusselt and Reynolds nubmers based on the wire diameter. The pressure drop decreased and the heat transfer increased as the wire diameter was decreased.
Hamaguchi, K.↗