Search results for "solar [axion]"
showing 10 items of 1352 documents
The Solar Spectroscopy Explorer Mission
2010
The Solar Spectroscopy Explorer (SSE) concept is conceived as a scalable mission, with two to four instruments and a strong focus on coronal spectroscopy. In its core configuration it is a small strategic mission ($250-500M) built around a microcalorimeter (an imaging X-ray spectrometer) and a high spatial resolution (0.2 arcsec) EUV imager. SSE puts a strong focus on the plasma spectroscopy, balanced with high resolution imaging - providing for break-through imaging science as well as providing the necessary context for the spectroscopy suite. Even in its smallest configuration SSE provides observatory class science, with significant science contributions ranging from basic plasma and radi…
Photospheric response to EB-like event
2016
Ellerman Bombs are signatures of magnetic reconnection, which is an important physical process in the solar atmosphere. How and where they occur is a subject of debate. In this paper we analyse Sunrise/IMaX data together with 3D MHD simulations that aim to reproduce the exact scenario proposed for the formation of these features. Although the observed event seems to be more dynamic and violent than the simulated one, simulations clearly confirm the basic scenario for the production of EBs. The simulations also reveal the full complexity of the underlying process. The simulated observations show that the Fe I 525.02 nm line gives no information on the height where reconnection takes place. I…
Does the Sun Shine byppor CNO Fusion Reactions?
2002
We show that solar neutrino experiments set an upper limit of 7.8% (7.3% including the recent KamLAND measurements) to the fraction of energy that the Sun produces via the CNO fusion cycle, which is an order of magnitude improvement upon the previous limit. New experiments are required to detect CNO neutrinos corresponding to the 1.5% of the solar luminosity that the standard solar model predicts is generated by the CNO cycle.
XMM observations of NGC 2516 stars
2007
We present the characteristics of the X-ray variability of stars in the cluster NGC 2516 as derived from XMM-Newton/EPIC/pn data. The X-ray variations on short (hours), medium (months), and long (years) time scales have been explored. We detected 303 distinct X-ray sources by analysing six EPIC/pn observations; 194 of them are members of the cluster. Stars of all spectral types, from the early-types to the late-M dwarfs, were detected. Cone search capability for table J/A+A/456/977/table2 (X-ray and optical properties of NGC 2516 members in the XMM-Newton/EPIC/pn observations having more than 25 counts.)
XMM spectroscopy of TWA 5
2006
We present results of X-ray spectroscopy for TWA 5, a member of the young TW Hydrae association, observed with XMM-Newton. TWA 5 is a multiple system which shows H{alpha} emission, a signature typical of classical T Tauri stars, but no infrared excess. From this analysis of the RGS and EPIC spectra, we have derived the emission measure distribution vs. temperature of the X-ray emitting plasma, its abundances, and the electron density.
XMM-Newton survey of two Upper Scorpius regions
2007
We studied X-ray emission from young stars by analyzing the deep XMM-Newton observations of two regions of the Upper Scorpius association with an age of 5Myr. Based on near infrared and optical photometry we identified 22 Upper Scorpius photometric members among the 224 detected X-ray sources. We derived coronal properties of Upper Scorpius stars by performing X-ray spectral and timing analyses. The study of four strong and isolated stellar flares allowed us to derive the length of the flaring loops. Cone search capability for table J/A+A/459/199/tableb1 (Sources detected in the CTIO observations) Cone search capability for table J/A+A/459/199/tablec1 (Sources detected in the Danish 1.54m o…
Stars associated to Eagle Nebula (M16=NGC6611)
2011
Massive star-forming regions are characterized by intense ionizing fluxes, strong stellar winds and, occasionally, supernovae explosions, all of which have important effects on the surrounding media, on the star-formation process and on the evolution of young stars and their circumstellar disks. We present a multiband study of the massive young cluster NGC 6611 and its parental cloud (the Eagle Nebula) with the aim of studying how OB stars affect the early stellar evolution and the formation of other stars. We search for evidence of triggering of star formation by the massive stars inside NGC 6611 on a large spatial scale (~10 parsec) and ongoing disk photoevaporation in NGC 6611 and how it…
Blue stars with disk photometry in NGC 6611
2010
NGC 6611 and its parental cloud, the Eagle Nebula (M 16), are well-studied star-forming regions, thanks to their large content of both OB stars and stars with disks and the observed ongoing star formation. In our previous studies of the Eagle Nebula, we identified 834 disk-bearing stars associated with the cloud, after detecting their excesses in NIR bands from J band to 8.0um. In this paper, we study in detail the nature of a subsample of disk-bearing stars that show peculiar characteristics. They appear older than the other members in the V vs. V-I diagram, and/or they have one or more IRAC colors at pure photospheric values, despite showing NIR excesses, when optical and infrared colors …
Nebular emission lines towards NGC3372 center
2016
We present observations from the Gaia-ESO Survey in the lines of H{alpha}, [NII], [SII], and He I of nebular emission in the central part of the Carina nebula. We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV>50km/s) gas emission. We show that gas giving rise to H{alpha} and HeI emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [SII] doublet ratios. The spatial variatio…
Infrated photometry of NGC 1893
2008
The independence of the star formation processes with respect to the environmental conditions is controversial. In particular it is not clear whether star formation in the outer Galaxy, where the environmental conditions are, theoretically, less conducive, occurs in the same way as in the inner Galaxy. We investigate the population of NGC 1893, a young cluster (~3-4Myr) in the outer part of the Galaxy (galactic radius >11kpc) in order to explore the effects of environmental conditions on star forming regions. We present the infrared observations obtained with the IRAC camera on board of the Spitzer Space Telescope and analyze the color-color diagrams to establish the membership of stars wit…