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1.
Elena Pavlenko Kirill Antoniuk Sergei Yu. Shugarov Nataly A. Katysheva Lenie Muzhdabaeva Vyacheslav Mikhajlov 《Astrophysics and Space Science》2005,296(1-4):461-464
We present results of multicolour photometry of the nova-like binary MV Lyr in the years 2002–2003, corresponding to the transition
of the star from its low (V = 17.8) to high (V = 12.3) brightness state. The transition lasted at most 200 days. During the first ∼50 days MV Lyr brightened at the rate
0.06 mag/day, and during the next ∼150 days at the rate 0.01 mag/day. The brightening was accompanied by a blue shift from
0.45 to 0.05 in V−R, interpreted as an increase of the accretion disk contribution to the total light. During the transition MV Lyr displayed
well-known ‘quasi-orbital’ light variations and fast quasi-periodic oscillations with a typical time scale of tens of minutes. 相似文献
2.
We present the results of our infrared observations of WR 140 (=V1687 Cyg) in 2001–2010. Analysis of the observations has
shown that the J brightness at maximum increased near the periastron by about 0
m
.3; the M brightness increased by ∼2
m
in less than 50 days. The minimum J brightness and the minimum L and M brightnesses were observed 550–600 and 1300–1400 days after the maximum, respectively. The JHKLM brightness minimum was observed in the range of orbital phases 0.7–0.9. The parameters of the primary O5 component of the
binary have been estimated to be the following: R(O5) ≈ 24.7R
⊙, L(O5) ≈ 8 × 105
L
⊙, and M
bol(O5) ≈ −10
m
. At the infrared brightness minimum, T
g ∼ 820–880 K, R
g ≈ 2.6 × 105
R
⊙, the optical depth of the shell at 3.5 μm is ∼5.3 × 10−6, and its mass is ≈1.4 × 10−8
M
⊙. At the maximum, the corresponding parameters are ∼1300 K, 8.6 × 104
R
⊙, ∼2 × 10−4, and ∼6 × 10−8
M
⊙; the mean rate of dust inflow (condensation) into the dust structure is ∼3.3 × 10−8
M
⊙ yr−1. The mean escape velocity of the shell from the heating source is ∼103 km s−1 and the mean dispersal rate of the shell is ∼1.1 × 10−8
M
⊙ yr−1. 相似文献
3.
Y. D. Mayya 《Journal of Astrophysics and Astronomy》1991,12(4):319-331
Calibration of the CCD camera of the 1m telescope at the Vainu Bappu Observatory, Kavalur, to theB V R system is reported here based on the observations of stars in the ‘dipper asterism’ in the open cluster M 67 (NGC 2682).
Transformations involvingB andV have negligible colour terms, while those involvingR are slightly colour dependent. The possibility of using scaled-downR band fluxes to estimate the continuum flux at Hα is investigated by comparing the counts inR band with those through an interference filter centred at Hα. The scaling factor is found to remain constant over a wide
range of colours. The sensitivity of the telescope-filter-CCD combination is estimated to be 2.0 per cent, 8.3 per cent and
9.7 per cent inB, V andR bands, respectively. The star F117 appears to be a small-amplitude (∼ 0.05 mag) variable. 相似文献
4.
Photometric observations of the eccentric eclipsing binary V1143 Cyg were performed during Aug.–Sep. 2000 and July 2002, in
Johnson B and V bands. The analysis of both light curves was made separately using the 1998 version of Wilson’s LC code. In order to find
a new observed rate of apsidal motion, we followed the procedure described by Guinan and Maloney (1985). A new observed rate
of apsidal motion of 3∘.72/100 yr was computed, which is close to the one reported earlier by Khaliullin (1983), Gimenez and Margrave (1985), and
Burns et al. (1996). 相似文献
5.
Interstellar and atmospheric extinctions redden the observational photometric data and they should be handled rigorously.
This paper simulates the effect of reddening for the modest case of two main sequence T
1 = 6500 K and T
2 = 5500 K components of a detached eclipsing binary system. It is shown that simply subtracting a constant from measured magnitudes
(the approach often used in the field of eclipsing binaries) to account for reddening should be avoided. Simplified treatment
of the reddening introduces systematics that reaches ∼0.01 mag for the simulated case, but can be as high as ∼0.2 mag for,
e.g., B8 V-K4 III systems. With rigorous treatment, it is possible to uniquely determine the colour excess value E(B−V) from multi-colour photometric light curves of eclipsing binaries. 相似文献
6.
Results of three-colour VRI CCD photometry are presented obtained during 11 nights in 2001. Twelve new minima timings are derived. The eclipse depth
decreases with wavelength, being equal to 1.28, 1.13 and 1.02 for V, R and I, respectively. The instrumental magnitudes and colours are tabulated for the mid-eclipse, out-of-eclipse part and the eclipsed
component. The V−R colour of the eclipsed component of emission is by 0.22 mag bluer than that for mid-eclipse, indicating a much higher temperature
of the eclipsed region. 相似文献
7.
Belinda Kalomeni E. Rennan PekÜnlÜ Kadri Yakut 《Astrophysics and Space Science》2005,296(1-4):477-480
In this study, we present a photometric study of AM Her, a prototype of a class of magnetic CVs. Optical photometry of AM
Her was obtained using the Russian–Turkish 1.5 m telescope at TüBİTAK National Observatory (TUG) in August 2003. The R band light curve of the system shows two maxima and two minima during one orbital cycle. In both observing nights the star
showed flickering at a significant level. The measured flickering time scale is about 5 min. 相似文献
8.
Sergei Yu. Shugarov Vitalij P. Goranskij Nataly A. Katysheva Anatolij V. Kusakin Nataly V. Metlova Igor M. Volkov DrahomÍr Chochol Theodor Pribulla Eugenia A. Karitskaja Alon Retter Ohad Shemmer Yiftah Lipkin 《Astrophysics and Space Science》2005,296(1-4):431-434
UBVRI photoelectric and CCD photometry of the slow nova V723 Cas obtained in the years 1995–2003 is presented. The evolution
of light curves in 1-year intervals, folded with the orbital period 0.69326 days, shows an increase of the amplitude of the
wave-like variations from 0.07 to 1.3 mag during the years 1997–2003. The fact that the shape and amplitude of the orbital
light curves does not depend on wavelength is most probably related to the geometry of eclipses combined with the distribution
of circumstellar matter in the system. 相似文献
9.
R and I band CCD observations of the nova V1494 Aql during July-November 2002 are reported and the V, R, and I light curves are analyzed. The orbital light curve of this nova has an eclipse-like form with two unequal humps before and after the eclipse. The approach to the eclipse lasts twice as long as the emergence from it. The overall duration of the eclipse is about 0.45P
orb. The depth of eclipse increases with wavelength and averages 0m.3 (V), 0m.5 (R), and 0m.7 (I). The secondary, shallow minimum has an average depth of 0m.1 in R and I and about 0m.03 in V. The hump at phase 0.65 is higher than the one at phase 0.17. The most probable explanation for the observed variations in the light with the phase of the orbital period may be self eclipsing of the accretion column in the magnetic exploding variable (white dwarf) together with partial eclipsing of the accretion region by the secondary component. 相似文献
10.
Photoelectric observations of the RS CVn type non-eclipsing binary UX Arietis obtained at Nizamiah Observatory during the
observing seasons of 1975–76, 1981–82 and 1982–83 are presented. The light curve of UX Ari showed a distortion wave with an
amplitude inV varying from 0.02 mag during 1975–76 to 0.15 mag during 1982–83. An analysis of the available data shows that the light maximum
is almost constant. It is also evident that the light-curve minimum decreases as the wave amplitude increases. The constant
light at maximum,V = 6.51 ± 0.03 indicates the unspotted photospheric brightness. It is also suggested that the variation in meanV brightness is mainly due to spot activity and not due to intrinsic variation. 相似文献
11.
R. Neuhuser A. Koeltzsch St. Raetz T. O. B. Schmidt M. Mugrauer N. Young F. Bertoldi T. Roell T. Eisenbeiss M. M. Hohle M. Vako C. Ginski W. Rammo M. Moualla C. Broeg 《Astronomische Nachrichten》2009,330(5):493-503
We report new photometric observations of the ∼200 000 year old naked weak‐line run‐away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the broad band filters B, V, R, and I using the 90 cm Dutch telescope on La Silla, the 80 cm Wendelstein telescope, and a 25 cm telescope of the University Observatory Jena in Großschwabhausen near Jena. The photometric data in V and R are consistent with a ∼5.7 day rotation period due to spots, as observed before between 1960ies and 2000. Also, for the first time, we present evidence for a long‐term 9 or 17.5 year cycle in photometric data (V band) of such a young star, a cycle similar to that to of the Sun and other active stars (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
David G. Turner 《Astrophysics and Space Science》2012,337(1):303-312
A reanalysis of the (seemingly very distant) open cluster Shorlin 1, the group of stars associated with WR 38 and WR 38a,
is made on the basis of existing UBV and JHK
s observations for cluster members. The 2MASS observations, in particular, imply a mean cluster reddening of E
B−V
=1.45±0.07 and a distance of 2.94±0.12 kpc. The reddening agrees with the UBV results provided that the local reddening slope is described by E
U−B
/E
B−V
=0.64±0.01, but the distance estimates in the 2MASS and UBV systems agree only if the ratio of total-to-selective extinction for the associated dust is R=A
V
/E
B−V
=4.0±0.1. Both results are similar to what has been obtained for adjacent clusters in the Eta Carinae region by similar analyses,
which suggests that “anomalous” dust extinction is widespread through the region, particularly for groups reddened by relatively
nearby dust. Dust associated with the Eta Carinae complex itself appears to exhibit more “normal” qualities. The results have
direct implications for the interpretation of distances to optical spiral arm indicators for the Galaxy at ℓ=287°–291°, in particular the Carina arm here is probably little more than ∼2 kpc distant, rather than 2.5–3 kpc distant as
implied in previous studies. Newly-derived intrinsic parameters for the two cluster Wolf-Rayet stars WR 38 (WC4) and WR 38a
(WN5) are in good agreement with what is found for other WR stars in Galactic open clusters, which was not the case previously. 相似文献
13.
We describe technical aspects of an astrometric and photometric survey of the North Celestial Cap (NCC), from the Pole (δ=90°) to δ=80°, in support of the TAUVEX mission. This region, at galactic latitudes from ∼17° to ∼37°, has poor coverage in modern
CCD-based surveys. The observations are performed with the Wise Observatory one-meter reflector and with a new mosaic CCD
camera (LAIWO) that images in the Johnson–Cousins R and I bands a one-square-degree field with sub-arcsec pixels. The images are treated using IRAF and SExtractor to produce a final
catalogue of sources. The astrometry, based on the USNO-A2.0 catalogue, is good to ∼1 arcsec and the photometry is good to
∼0.1 mag for point sources brighter than R=20.0 or I=19.1 mag. The limiting magnitudes of the survey, defined at photometric errors smaller than 0.15 mag, are 20.6 mag (R) and 19.6 (I). We separate stars from non-stellar objects based on the object shapes in the R and I bands, attempting to reproduce the SDSS star/galaxy dichotomy. The completeness test indicates that the catalogue is complete
to the limiting magnitudes. 相似文献
14.
Results from optical photometric observations of the PMS star V 1735 Cyg are reported. The star is located in the IC 5146
dark cloud complex—a region of active star formation. On the basis of observed outburst and spectral properties, V 1735 Cyg
was classified as a FUor object. We present data from BVRI CCD photometric observations of the star, collected from March 2003 to January 2009. Plates from the Rozhen Schmidt telescope
archive were scanned for a brightness estimation of the star. A sequence of sixteen comparison stars in the field of V 1735
Cyg was calibrated in BVRI bands. The data from photographic observations made from 1986 to 1992 show a strong light variability (ΔV=1⋅m2). In contrast, the recent photometric data obtained from 2003 to 2009 show only small amplitude variations (ΔI=0⋅m3). The analysis of existing photometric data shows a very slow decrease in star brightness—1⋅m8 (R) for a 44 year period. The possibilities for future photometric investigations of V 1735 Cyg using the photographical
plate archives is discussed briefly. 相似文献
15.
A. Fritz B.L. Ziegler R.G. Bower I. Smail R.L. Davies 《Astrophysics and Space Science》2003,285(1):61-66
We explore the evolution of the early-type galaxy population in the rich cluster Abell 2390 at z=0.23. For this purpose, we have obtained spectroscopic data of 51 elliptical and lenticular galaxies with MOSCA at the 3.5
m telescope on Calar Alto Observatory. As our investigation spans both a broad range in luminosity (–22.3≤MB≤–:19.3)and a wide field of view (10′×10′), the environmental dependence of different formation scenarios can be analysed
in detail as a function of radius from the cluster center. In this paper, we present first results on the Faber-Jackson relation
and, for a subsample of 14 galaxies with morphological and structural parameters from HST, we also investigate the evolution
of the Kormendy relation and the Fundamental Plane. We find a mild luminosity evolution of the early-type galaxies in Abell
2390: our objects are on average brighter by m
B∼0.4 mag.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Photoelectric Vilnius seven-color photometry is presented and analyzed for a sample of 24 red giant branch and clump stars
in the open cluster NGC 7789. For each star we have determined photometric spectral type, absolute magnitude, interstellar
reddening, effective temperature, metallicity, and surface gravity. From averages over the stars in the sample we find the
mean reddening to the cluster E
Y−V
= 0.21± 0.02 (s.d.), or E
B−V
= 0.25, and the apparent distance modulus (m−M)
V
= 12.21± 0.10 (s.d.), which yield a distance of 1840 pc. The mean overall metallicity is found to be [Fe/H] = −0.18± 0.09
(s.d.). The clump stars, on average, appear to be slightly more metal-rich than the other red giants, which is most probably
caused by evolutionary changes of carbon and nitrogen molecular bands falling in the photometric passbands. A difference in
mass between the two groups of stars has also been detected, which suggests that the clump stars might have undergone extra
mass loss before reaching their core He-burning phase of evolution. 相似文献
17.
C. Sezer 《Astrophysics and Space Science》1993,208(1):15-31
Photoelectric observations of the eclipsing binary V 1073 Cyg have been carried out inB andV colours at the Ege University Observatory. The light curves were analyzed with the Wilson-Devinney approach. A period study reveals that the orbital period of the system is decreasing at the rate of (3.21 ± 0.17) second per century. 相似文献
18.
The O–C curve of the contact binary CK Boo have been analyzed with Kalimeris et al. (1994) method. It is shown that the orbital period is changing in a quasi-sinusoidal form with a period of about ∼ 14 yr
superposed on a secular period increase. The correlation of the variations of the light level at MinI, MaxI and II in the
light curve implies that the luminosity of secondary component is variable. Comparing the change of the quasi-periodic component
in the orbital period with that of the secondary's luminosity, we find that the luminosity of the secondary component and
the orbital period may vary with the same cycle length ∼14 yr; the variation of the secondary's luminosity is in the same
phase with that of the orbital period. This connection is different from those of the RS CVn-type close binaries (e.g. CG
Cyg, V471 Tau, RT Lac). The mechanisms that may have produced this relation of the variations of the orbital period and the
luminosity of the secondary are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Paolo Ciliegi Carlotta Gruppioni Richard McMahon Michhael Rowan-Robinson 《Astrophysics and Space Science》2001,276(2-4):957-964
The optical identification programme is presented for a complete sample of 867 radio sources that were observed with the Very
Large Array (VLA) within 4.22 deg2 to S
1.4 GHz ≥ 0.135 mJy (5 σ). The area covered by the VLA survey is part of the regions of the sky that have been surveyed in the mid
and far Infrared over the wavelength range 6.7–175 μmwith ISO as part of the European Large Area ISO Survey (ELAIS). Optical
identifications are made using the Automatic Plate-measuring Machine (APM) optical catalogue in E (∼ R) and O (∼ B) bands with approximate limiting magnitudes of ∼ 20.0 and 21.5 mag, respectively. For 220 out of the 867 radio sources, likely
identifications are proposed with an a posteriori identification percentage of 25%. The sample of identification has a reliability
of 96% and a completeness of 80%.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
S. Bilir T. Güver I. Khamitov T. Ak S. Ak K. B. Coşkunoğlu E. Paunzen E. Yaz 《Astrophysics and Space Science》2010,326(1):139-150
We present CCD BV and JHK
s
2MASS photometric data for the open cluster NGC 1513. We observed 609 stars in the direction of the cluster up to a limiting
magnitude of V∼19 mag. The star-count method showed that the centre of the cluster lies at α
2000=04
h
09
m
36
s
, δ
2000=49°28′43″ and its angular size is r=10 arcmin. The optical and near-infrared two-colour diagrams revealed the colour excesses in the direction of the cluster
as E(B−V)=0.68±0.06, E(J−H)=0.21±0.02 and E(J−K
s
)=0.33±0.04 mag. These results are consistent with normal interstellar extinction values. Optical and near-infrared Zero Age
Main-Sequences (ZAMS) provided an average distance modulus of (m−M)0=10.80±0.13 mag, which can be translated into a distance of 1440±80 pc. Finally, using Padova isochrones we determined the
metallicity and age of the cluster as Z=0.015±0.004 ([M/H]=−0.10±0.10 dex) and log (t/yr)=8.40±0.04, respectively. 相似文献