Search results for "solar [matter]"
showing 10 items of 1254 documents
The ALHAMBRA survey: Accurate merger fractions by PDF analysis of photometric close pairs
2014
Our goal is to develop and test a novel methodology to compute accurate close pair fractions with photometric redshifts. We improve the current methodologies to estimate the merger fraction f_m from photometric redshifts by (i) using the full probability distribution functions (PDFs) of the sources in redshift space, (ii) including the variation in the luminosity of the sources with z in both the selection of the samples and in the luminosity ratio constrain, and (iii) splitting individual PDFs into red and blue spectral templates to deal robustly with colour selections. We test the performance of our new methodology with the PDFs provided by the ALHAMBRA photometric survey. The merger frac…
The B0.5IVe CoRoT target HD 49 330. I. Photometric analysis from CoRoT data
2009
Context. Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. Aims. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the β Cephei instability strip in the HR diagram and showed a 0.03 mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis. Methods. We analyze the CoRoT light curve of HD 49330 usin g Fourier methods and non-lin ear least square fitting. Resul…
The ALHAMBRA Project: A large area multi medium-band optical and NIR photometric survey
2008
(ABRIDGED) We describe the first results of the ALHAMBRA survey which provides cosmic tomography of the evolution of the contents of the Universe over most of Cosmic history. Our approach employs 20 contiguous, equal-width, medium-band filters covering from 3500 to 9700 A, plus the JHKs bands, to observe an area of 4 sqdeg on the sky. The optical photometric system has been designed to maximize the number of objects with accurate classification by SED and redshift, and to be sensitive to relatively faint emission lines. The observations are being carried out with the Calar Alto 3.5m telescope using the cameras LAICA and O-2000. The first data confirm that we are reaching the expected magnit…
Attributes of flares in Gamma Ray Bursts: sample I
2007
We discuss some of the preliminary results and findings derived from the analysis of a first sample of flares detected by the XRT on board Swift. The analysis shows that the morphology of flares is the one we expect from the collision of ultra-relativistic shells as it happens during the internal shock model proposed by Rees and Meszaros in 1994. Furthermore the Delta(t)/t ratio and the decay-time to rise-time ratio have mean values that are in good agreement with the values observed in the prompt emission pulses that are believed to originate from internal shocks. The conclusion is that the flare analysis favors the internal shock as due to shells that have been ejected by the central engi…
Photometric observations of the radio bright B[e]/X-ray binary CI Cam
2000
We present multiwavelength (optical, IR, radio) observations of CI Cam, the optical counterpart to the transient X-ray source XTE J0421+560. Pre-outburst quiescent observations reveal the presence of a dusty envelope around the system. Pronounced short term variability is observed at all wavebands from U-K, but no indication of prior flaring of a similar magnitude to the 1998 April outburst is found in these data.\ud \ud Data obtained during the 1998 April X-ray flare reveal pronounced optical-radio flaring. The optical flux was observed to quickly return to quiescent levels, while the radio flare was of much longer duration. The optical component is likely to result from a combination of f…
Measurement of key resonance states for the P30(p,γ)S31 reaction rate, and the production of intermediate-mass elements in nova explosions
2017
We report the first experimental constraints on spectroscopic factors and strengths of key resonances in the P30(p,γ)S31 reaction critical for determining the production of intermediate-mass elements up to Ca in nova ejecta. The P30(d,n)S31 reaction was studied in inverse kinematics using the GRETINA γ -ray array to measure the angle-integrated cross-sections of states above the proton threshold. In general, negative-parity states are found to be most strongly produced but the absolute values of spectroscopic factors are typically an order of magnitude lower than predicted by the shell-model calculations employing WBP Hamiltonian for the negative-parity states. The results clearly indicat…
Canopy directional emissivity: Comparison between models
2005
Land surface temperature plays an important role in many environmental studies, as for example the estimation of heat fluxes and evapotranspiration. In order to obtain accurate values of land surface temperature, atmospheric, emissivity and angular effects should be corrected. This paper focuses on the analysis of the angular variation of canopy emissivity, which is an important variable that has to be known to correct surface radiances and obtain surface temperatures. Emissivity is also involved in the atmospheric corrections since it appears in the reflected downwelling atmospheric term. For this purpose, five different methods for simulating directional canopy emissivity have been analyz…
XMM-Newton detection of the 2.1 ms coherent pulsations from IGR J17379-3747
2018
We report on the detection of X-ray pulsations at 2.1 ms from the known X-ray burster IGR J17379-3747 using XMM-Newton. The coherent signal shows a clear Doppler modulation from which we estimate an orbital period of ~1.9 hours and a projected semi-major axis of ~8 lt-ms. Taking into account the lack of eclipses (inclination angle of < 75 deg) and assuming a neutron star mass of 1.4 Msun, we estimated a minimum companion star of ~0.06 Msun. Considerations on the probability distribution of the binary inclination angle make less likely the hypothesis of a main-sequence companion star. On the other hand, the close correspondence with the orbital parameters of the accreting millisecond puls…
High redshift galaxies in the ALHAMBRA survey. II. Strengthening the evidence of bright-end excess in UV luminosity functions at 2.5 <= z<= 4.5 by PD…
2018
Context. Knowing the exact shape of the ultraviolet (UV) luminosity function (LF) of high-redshift galaxies is important to understand the star formation history of the early Universe. However, the uncertainties, especially at the faint and bright ends of the LFs, remain significant. Aims. In this paper, we study the UV LF of redshift z = 2:5 4.5 galaxies in 2.38 deg of ALHAMBRA data with I ≤ 24. Thanks to the large area covered by ALHAMBRA, we particularly constrain the bright end of the LF. We also calculate the cosmic variance and the corresponding bias values for our sample and derive their host dark matter halo masses. Methods.We have used a novel methodology based on redshift and magn…
A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371
2015
We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at $\sim 0.7$ keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering …