In a deep X-ray survey of the Pleiades open cluster, we use the ROSAT High Resolution Imager to explore a region of the cluster formerly surveyed with the PSPC. These new observations substantially improve upon both the sensitivity and the spatial resolution for this region of the Pleiades, allowing us to detect 18 cluster members not detected before and 16 members not included in the catalogs ...

We present the first results of an XMM-Newton EPIC survey of NGC 2516, a southern low-metallicity open cluster with an age close to the Pleiades. The attained limiting sensitivity is of ∼ 2.4×10 erg sec cm in the 0.1–4.0 keV bandpass. This has been achieved by summing the data of the MOS and PN cameras of two distinct observations for a total exposure time of ∼ 33 ks and by analyzing the summed...

We present a comprehensive analysis of X-ray variability of the late-type (dF7-dM) Pleiades stars, detected in all ROSAT-PSPC observations; X-ray variations on short (hours) and medium (months) time scales have been explored. We have grouped the stars in two samples: 89 observations of 42 distinct dF7-dK2 stars and 108 observations of 61 dK3-dM stars. The Kolmogorov-Smirnov test applied on all ...

ORFEO, the PLEIADES Accompaniment Program, was set up by CNES, the French Space Agency, to prepare, accompany and promote the use and the exploitation of the images acquired by this Very High Resolution optical sensor. It was initiated in 2004 and will last until the end of the first year of the satellite life (launched in December 2011) . The Thematic part of the ORFEO accompaniment program co...

We report deep 3.6 cm radio observations of six very rapidly rotating late-type dwarf stars in the Pleiades open cluster, distributed in spectral class from F9 to M0. This study, supplemented by our previous radio detections of three G8-K2 dwarfs in the Pleiades (Lim & White 1995; hereinafter LW95), completes our small census of Pleiades ultrafast rotators with spectral types spanning the range...

We present a search for low-mass brown dwarfs in the Pleiades open cluster. The identification of Pleiades members fainter and cooler than those currently known allows us to constrain evolutionary models for L dwarfs and to extend the study of the cluster mass function to lower masses. We conducted a 1.8 deg2 near-infrared J-band survey at the 3.5 m Calar Alto Telescope, with completeness Jcpl ...

سپیدایی از ﭘﺎراﻣﺘﺮﻫﺎی ﻣﻮرد ﻧﻴﺎز در ﻣﻄﺎﻟﻌﺎت زﻳﺴﺖ‌ﻣﺤﻴﻄﻲ و آب‌و‌ﻫﻮاﻳﻲ به‌شمار می‌رود؛ ازاین‌رو، بررسی رفتار زمانی مکانی آن می‌تواند ابزاری برای شناخت تغییرات محیطی باشد. ﺳﻨﺠﻨﺪة مودیس ﺳﻄﺢ زﻣﻴﻦ را به‌طور ﻣﺴﺘﻤﺮ، ﻣﻘﻴﺎﺳﻲ ﺟﻬﺎﻧﻲ ﺑﺎ ﻗﺪرت ﺗﻔﻜﻴﻚ ﻣﻜﺎﻧﻲ مناسب ﺗﻮﻟﻴﺪ دسترس پژوهشگران ﻗﺮار داده است. این پژوهش، واکاوی موانع برداشت/ دیدبانی ایران‌زمین، نخست داده‌های روزانة سنجندة محدودة ایران، بازة 1/1/1379 تا 10/1...

We present spectroscopic observations of candidate F, G and K type stars in NGC 6633, an open cluster with a similar age to the Hyades. From the radial velocities and metal-line equivalent widths we identify 10 new cluster members including one short period binary system. Combining this survey with that of Jeffries (1997), we identify a total of 30 solar-type members. We have used the F and ear...

Involved in disaster management support for more than 10 years, SERTIT’s Rapid Mapping Service is specialized in the rapid delivery of crisis information derived from Earth Observation satellite imagery, in particular within the framework of the International Charter “Space and Major Disasters” or European and National emergency programs. This service, available 24/7/365, provides in a rush mod...