Abstract. The study of a sky area with a 20 degree diameter centered on the nearby association Per OB2 has been carried out on the basis of the "Compiled Catalogue of Astronomical Data in the Per OB2 Field" presented in a previous paper. The catalogue contains about 30 000 stars with accurate proper motions in the Hipparcos system as well as magnitudes supplemented with spectral classes and other relevant data. We applied the reduced proper motion technique to estimate individual distances for almost all catalogue stars. The distributions of reddening and interstellar extinction were determined on the basis of the spectral classification of stars in the area. Proper motions were corrected for differential rotation of the Galactic disk and parallactic motion effects and used for the evaluation of association membership. The analysis of a uniform subset of main sequence (MS) stars earlier than A7 -which is complete within 500 pc -has clearly revealed the association as an area of enhanced density with an angular size of about 7• . In comparison to the previous results on Per OB2, we show that the presently determined area extends the association from its classical position towards the California nebula and the Auriga dark cloud. There are 1025 MS proper motion members residing in this region. The distance to the association centre derived from a kinematic calibration is found to be about 300 pc i.e., in perfect agreement with the Hipparcos data. The shape of the association is almost spherical, and its diameter found from stellar counts is about 40 pc. An examination of internal systematic motions from proper motion data has shown that there is no evidence of an expansion or a rotation of the association around the line of sight. The average tangential and spatial velocity vectors of Per OB2 with respect to the LSR are determined as (V l , V b ) = (+7.2 ± 0.4, +2.0 ± 0.3) km s −1 and (U, V, W ) = (+12.7 ± 1.6, −3.0 ± 0.6, −0.9 ± 0.8) km s −1 .
Abstract. A compiled catalogue of astrometric and photometric data for about 2200 stars down to V = 16.8 m is presented. The stars are located in an area with a radius of 22.8 arcmin around the extremely young open cluster NGC 6611 with the cluster center at (α, δ) 2000.0 = 18 h 18 m 40 s , −13• 47.1 . The catalogue is based on new reductions of positions, proper motions, and of photometric data that have been published in this region and includes, among others, Hipparcos, AC/GSC and Tautenburg Schmidt plate observations. For the membership determination, spatial and proper motion distributions of stars in the region were analysed. An extinction map of the area and the cluster color-magnitude diagram down to M V = +1 m were constructed. The distance of NGC 6611 was determined as 2.14 ± 0.10 kpc.
In this paper we present the various concepts behind the Astro-WISE Information System. The concepts form a blueprint for general scientific information systems (WISE) which can satisfy a wide and challenging range of requirements for the data dissemination, storage and processing for various fields in science. We review the main features of the information system and its practical implementation.Comment: 21 pages, 6 figures, accepted by Experimental Astronomy for topical issue on Astro-WIS
Based on the CCD observations of remote young open clusters NGC 2383, NGC 2384, NGC 4103, NGC 4755, NGC 7510 and Hogg 15, we construct their observed luminosity functions (LFs). The observed LFs are corrected for field star contamination determined with the help of galactic star count model. In the case of Hogg 15 and NGC 2383 we also considered the additional contamination from neighboring clusters NGC 4609 and NGC 2384 respectively. These corrections provided the realistic pattern of cluster LF in the vicinity of the MS turn on point and at fainter magnitudes, revealed the so called H-feature arising due to transition of the Pre-MS phase to MS, which is dependent on the cluster age. The theoretical LFs were constructed representing a cluster population model with continuous star formation for a short time scale and a power law Initial Mass Function (IMF) and these were fitted to the observed LF. As a result we are able to determine for each cluster a set of parameters, describing cluster population (the age, duration of star formation, IMF slope, and percentage of field star contamination). It was found that in spite of the non-monotonic behavior of observed LFs, cluster IMFs can be described as the power law functions with slopes similar to Salpeter's value. The present Main Sequence turn on cluster ages are several times lower than those derived from the fitting of theoretical isochrones to turn off region of the upper Main Sequences.
these problems. We give examples of applications running on Astro-WISE and EGEE and review future development of the merged system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.