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מאמרים קשורים
Optical and infrared properties of V1647 Orionis during the 2003-2006 outburst. I. The reflection nebula
Aims.The recent outburst of the young eruptive star V1647Orionis has produced a spectacular appearance of a newreflection nebula in Orion (McNeil's nebula). Wepresent an optical/near infrared investigation of McNeil's nebula. Thisanalysis is aimed at determining the morphology, temporal evolution andnature of the nebula and its connection to the outburst. Methods: Weperformed multi epoch B, V, R_C, I_C, z_gunn, and KS imagingof McNeil's nebula and V1647 Ori as well as KS imagingpolarimetry. The multiband imaging allows us to reconstruct theextinction map inside the nebula. Through polarimetric observations weattempt to disentangle the emission from the nebula from that of theaccretion disk around V1647 Ori. We also attempt to resolve the smallspatial scale structure of the illuminating source. Results: The energydistribution and temporal evolution of McNeil's nebula mimic that of theilluminating source. The extinction map reveals a region of higherextinction in the direction of V1647 Ori. Excluding foregroundextinction, the optical extinction due to McNeil's nebula in thedirection of V1647 Ori is AV ~ 6.5 mag. The polarimetricmeasurement shows a compact high polarization emission around V1647 Ori.The percentage of KS band linear polarization goes from10-20%. The vectors are all well aligned with a position angle of90° ± 9° East of North. This may correspond to theorientation of a possible accretion disk around V1647 Ori. Thesefindings suggest that the appearance of McNeil's nebula is due toreflection of light by pre-existing material in the surroundings ofV1647 Ori. We also report on the discovery of a new candidate browndwarf or protostar in the vicinity of V1647 Ori as well as the presenceof clumpy structure within HH 22A.
| Walraven photometry of nearby southern OB associations
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
| UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
| UBV photometry of E region standard stars of intermediate brightness
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
| Atmospheric extinction in the /U-B/ color index
Various methods for obtaining the atmospheric extinction in the (U-B)color index taking into account the dependence of extinction coefficienton the intrinsic color index of the star are examined. Numericalintegrations are performed to determine synthetic color indices for 32stars of spectral classes O9 to M0 and luminosity classes I, III and Vthrough 0, 1 and 2 air masses, resulting in three (u-b) color indicesfor each star. Photometric reduction of the color indices to the (U-B)color index was then performed by the classical method, by the methodproposed by Gutierrez-Moreno et al. (1966) and various modifications ofit, and by the method proposed by Moffat and Vogt (1977). Comparisonwith observations of 71 stars in the standard region E5, nine extinctionstandard stars and 25 Johnson standard stars in the UBV reveals that thereduction of (U-B) by the classical method gives internal errors betweentwo and three times larger than those obtained for (B-V) and V, whilethe methods of Gutierrez-Moreno et al. and Moffat and Vogt providegreatly improved accuracy.
| Photometric standard stars for the UBV and (RI)KC systems.
Not Available
| Fainter Standards for VRI Photometry in the E Regions
Not Available
| Standard magnitudes in the E regions.
Not Available
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הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | קנטאור |
| התרוממות ימנית: | 11h54m23.55s |
| סירוב: | -46°29'29.9" |
| גודל גלוי: | 7.972 |
| מרחק: | 231.481 פארסק |
| תנועה נכונה: | -9.9 |
| תנועה נכונה: | -20.4 |
| B-T magnitude: | 9.168 |
| V-T magnitude: | 8.071 |
קטלוגים וכינוים:
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