scholarly journals The nature of the companion in the Wolf-Rayet system EZ Canis Majoris

2020 ◽  
Vol 639 ◽  
pp. A18 ◽  
Author(s):  
G. Koenigsberger ◽  
W. Schmutz
Keyword(s):  
Light Curve ◽  
Model Fit ◽  
Heated Region ◽  
Orbital Elements ◽  
Binary Nature ◽  
Heated Zone ◽  
Binary Model ◽  
International Ultraviolet Explorer ◽  
Simultaneous Model ◽  
Rayet Star

Context. EZ Canis Majoris is a classical Wolf-Rayet star whose binary nature has been debated for decades. It was recently modeled as an eccentric binary with a periodic brightening at periastron of the emission originating in a shock heated zone near the companion. Aims. The focus of this paper is to further test the binary model and to constrain the nature of the unseen close companion by searching for emission arising in the shock-heated region. Methods. We analyze over 400 high resolution International Ultraviolet Explorer spectra obtained between 1983 and 1995 and XMM-Newton observations obtained in 2010. The light curve and radial velocity (RV) variations were fit with the eccentric binary model and the orbital elements were constrained. Results. We find RV variations in the primary emission lines with a semi-amplitude K1 ∼ 30 km s−1 in 1992 and 1995, and a second set of emissions with an anti-phase RV curve with K2 ∼ 150 km s−1. The simultaneous model fit to the RVs and the light curve yields the orbital elements for each epoch. Adopting a Wolf-Rayet mass M1 ∼ 20 M⊙ leads to M2 ∼ 3−5 M⊙, which implies that the companion could be a late B-type star. The eccentric (e = 0.1) binary model also explains the hard X-ray light curve obtained by XMM-Newton and the fit to these data indicates that the duration of maximum is shorter than the typical exposure times. Conclusions: The anti-phase RV variations of two emission components and the simultaneous fit to the RVs and the light curve are concrete evidence in favor of the binary nature of EZ Canis Majoris. The assumption that the emission from the shock-heated region closely traces the orbit of the companion is less certain, although it is feasible because the companion is significantly heated by the WR radiation field and impacted by the WR wind.

scholarly journals The Massive Close Binary in the δ Ori A Triple System

2002 ◽  
Vol 187 ◽  
pp. 47-52
Author(s):  
James A. Harvin ◽  
Douglas R. Gies
Keyword(s):  
Cross Correlation ◽  
Short Wave ◽  
Close Binary ◽  
Full Description ◽  
High Dispersion ◽  
Orbital Elements ◽  
Primary Star ◽  
International Ultraviolet Explorer ◽  
Triple Star ◽  
Massive Close Binary

AbstractWe present an analysis of short-wave, high-dispersion ultraviolet spectra of the triple star δ Ori A from the International Ultraviolet Explorer Satellite’s (IUE) Final Archive. These spectra were cross-correlated against AE Aur to find the components’ radial velocities, which were then used to produce the system’s orbital elements. The long-period tertiary star in the δ Ori A system was not seen in the resulting cross-correlation functions (CCFs). The close binary’s eclipses allow the orbit’s inclination to be estimated by modeling of its Hipparcos light curve. The primary star appears to have a mass of 11.2 M⊙ and the secondary seems to have a mass of 5.6 M⊙, both of which are about 1/3 of the expected values for stars of their MK types. Although we expected the massive close binary in the δ Ori A system to be a pre-Roche lobe overflow (RLOF) system, these masses appear to require that it be a post-RLOF system. The full description of this work, including the tomographic separation of the spectra for the close binary’s components, appears in Harvin et al. (2002).

scholarly journals A Comparison Between Binary Star Light Curves and Those of Possible Binary Asteroids

1984 ◽  
Vol 80 ◽  
pp. 387-392
Author(s):  
H. J. Schober
Keyword(s):  
Light Curve ◽  
Binary Star ◽  
Variable Stars ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Binary Asteroids ◽  
Binary Nature ◽  
Rotation Rates ◽  
Photoelectric Observations

AbstractSince about ten years coordinated programs of photoelectric observations of asteroids are carried out to derive rotation rates and light curves. Quite a number of those asteroids exhibit features in their light curves, with similar characteristics as variable stars and especially eclipsing binaries. This would allow also an interpretation that there might be an evidence for the binary nature of some asteroids, based on observational hints. A few examples are given and a list of indications for the possible binary nature of asteroids, based on their light curve features, is presented.

scholarly journals A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

2020 ◽  
Vol 492 (4) ◽  
pp. 5897-5915 ◽  
Author(s):  
Nathan Smith ◽  
Jennifer E Andrews ◽  
Maxwell Moe ◽  
Peter Milne ◽  
Christopher Bilinski ◽  
...  
Keyword(s):  
Wind Speed ◽  
Light Curve ◽  
Spectral Type ◽  
Fold Increase ◽  
Small Magellanic Cloud ◽  
Bolometric Luminosity ◽  
Type Spectrum ◽  
Low Metallicity ◽  
Rayet Star ◽  
Luminous Blue Variable

ABSTRACT MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20 yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data reveal that this star brightened in 2010, with a light curve resembling that of the classic LBV star AF And in M31. Other Ofpe/WN9 stars have erupted as LBVs, but MCA-1B was unusual because it remained hot. It showed a WN-type spectrum throughout its eruption, whereas LBVs usually get much cooler. MCA-1B showed an almost four-fold increase in bolometric luminosity and a doubling of its radius, but its temperature stayed ≳29 kK. As it faded, it shifted to even hotter temperatures, exhibiting a WN7/WN8-type spectrum, and doubling its wind speed. MCA-1B is reminiscent of some supernova impostors, and its location resembles the isolated environment of SN 2009ip. It is most similar to HD 5980 (in the Small Magellanic Cloud) and GR 290 (also in M33). Whereas these two LBVs exhibited B-type spectra in eruption, MCA-1B is the first clear case where a Wolf–Rayet (WR) spectrum persisted at all times. Together, MCA-1B, HD 5980, and GR 290 constitute a class of WN-type LBVs, distinct from S Doradus LBVs. They are most interesting in the context of LBVs at low metallicity, a possible post-LBV/WR transition in binaries, and as likely Type Ibn supernova progenitors.

scholarly journals Optical Observations of Recent Novae

1977 ◽  
Vol 42 ◽  
pp. 149-181
Author(s):  
B. Wolf
Keyword(s):  
Light Curve ◽  
Absolute Magnitude ◽  
Optical Observations ◽  
Variable Amplitude ◽  
Classical Novae ◽  
Binary Nature ◽  
M 10 ◽  
Speed Of Evolution

AbstractThe observations of two rather different classical novae, V 1500 Cyg (= Nova Cyg 1975) and NQ Vul (= Nova Vul 1976), are presented and compared. Nova Cyg 1975 is outstanding with respect to absolute magnitude (M = -10), range of brightening (Δm = 19), and speed of evolution (t3= 3.6 days). Its prenova object had to be fainter than about magnitude 9. The corresponding values for Nova Vul 1976 are rather conservative (M≈-7.5, Δm ≈ 12, t3=40 days, absolute magnitude of the prenova ≈4.5). The light curve of Nova Cyg 1975 is very smooth. Some superimposed photometric variations of a small and slightly variable amplitude of a period of 3.4 hours are most naturally ascribed to a binary nature of Nova Cyg 1975. Nova Vul 1976 has a completely different lighteurve with extremely strong rapid irregular variations of considerably amplitude. There is a remarkable second maximum about 14 days after discovery.

scholarly journals Spectrum Analysis of the Binary Star 53 Aur with a CP3 Component

1993 ◽  
Vol 138 ◽  
pp. 161-164
Author(s):  
Juraj Zverko ◽  
Ján Budaj ◽  
Milan Zboril ◽  
Jozef Žižňovský
Keyword(s):  
Spectrum Analysis ◽  
Total Mass ◽  
Binary Star ◽  
Rotational Velocity ◽  
High Dispersion ◽  
Orbital Elements ◽  
Binary Nature ◽  
Different Types ◽  
Magnitude Difference

The CP-star 53 Aur (HD 47152, HR 2425) has been assigned in the literature different types of peculiarity. Bertaud (1959) classified it as A0p-EuCr, Cowley et al. (1969) as B9p-Eu(Cr?), Osawa (1965) as Hg and Zverko (1974) as Mn -type. MacAlister (1978) discovered its binary nature and Tokovinin (1986) first determined its orbit with a period of 13.7 y. Subsequent interferometric observations by Baize (1989) yielded new orbital elements with a period of 25.816 y, total mass of 5.8 M⊙ and magnitude difference of two B9 components 0.3 mag. Adelman (1982) performed spectrophotometry and fitted the Balmer jump with Teff=10 500 K, while the Paschen continuum with Teff=9 500 K, log g=4 in both cases. Palmer (1965) estimated the projected rotational velocity to 325 km s−1 from the width of the Ca II-K line, while Wolff and Preston (1975) obtained 33 km s−1 from the Mg II 448.1 nm line. In this work we analyze high-dispersion spectra obtained in two distant orbital phases, namely in 1975 and in 1992 to distinguish the components of the system.

scholarly journals Physical properties of V1329 Cygni

1982 ◽  
Vol 70 ◽  
pp. 169-171
Author(s):  
T. Iijima
Keyword(s):  
Light Curve ◽  
Physical Properties ◽  
Type Systems ◽  
Mass Function ◽  
Eclipsing Binary ◽  
Long Period ◽  
Binary Model

In this paper, I shall present another model for V1329 Cyg. Grygar et al. (1979) proposed a long period eclipsing binary model consisting of a massive M giant and a hot component. Some problems, however, have remained on the binary model. Namely, the mass function is too large, the amplitude of the light variations changes from period to period, the light curve differs from that of Algol type systems and is similar to long period binaries, and so on (Iijima et al. 1981). It has been believed that some peculiarities in the system could explain those problems. Recently however, some phenomena which are inconsistent with the binary model were observed (Iijima and Mammano 1981).

scholarly journals The Light Variation and the Orbital Elements of am LEONIS = ADS 8024 A

1971 ◽  
Vol 5 ◽  
pp. 177-177
Author(s):  
L. Binnendijk
Keyword(s):  
Light Curve ◽  
Light Variation ◽  
National Observatory ◽  
Orbital Elements ◽  
Primary Minimum ◽  
Visual Component ◽  
Total Eclipse ◽  
Photometric Elements

AbstractThe star was followed photoelectrically in two colors through five consecutive nights in 1968 at Kitt Peak National Observatory. The light of the fainter visual component (a physical companion) was excluded. At primary minimum the system undergoes a total eclipse lasting 25 min. New internally consistent elements have been derived. A subluminous region on the larger star can be located. The previous light curve by Abrami leads to the same geometrical elements but to different photometric elements even when freed from the light of the distant companion.The paper appeared in Astron. J. 74, 1031 (1969).

scholarly journals PTF11mnb: First analog of supernova 2005bf

2018 ◽  
Vol 609 ◽  
pp. A106 ◽  
Author(s):  
F. Taddia ◽  
J. Sollerman ◽  
C. Fremling ◽  
E. Karamehmetoglu ◽  
R. M. Quimby ◽  
...  
Keyword(s):  
Light Curve ◽  
Rotation Period ◽  
Supernova Explosion ◽  
Light Curves ◽  
Main Peak ◽  
Optical Photometry ◽  
Early Peak ◽  
Envelope Model ◽  
Analytic Models ◽  
Rayet Star

Aims. We study PTF11mnb, a He-poor supernova (SN) whose light curves resemble those of SN 2005bf, a peculiar double-peaked stripped-envelope (SE) SN, until the declining phase after the main peak. We investigate the mechanism powering its light curve and the nature of its progenitor star. Methods. Optical photometry and spectroscopy of PTF11mnb are presented. We compared light curves, colors and spectral properties to those of SN 2005bf and normal SE SNe. We built a bolometric light curve and modeled this light curve with the SuperNova Explosion Code (SNEC) hydrodynamical code explosion of a MESA progenitor star and semi-analytic models. Results. The light curve of PTF11mnb turns out to be similar to that of SN 2005bf until ~50 d when the main (secondary) peaks occur at −18.5 mag. The early peak occurs at ~20 d and is about 1.0 mag fainter. After the main peak, the decline rate of PTF11mnb is remarkably slower than what was observed in SN 2005bf, and it traces well the 56Co decay rate. The spectra of PTF11mnb reveal a SN Ic and have no traces of He unlike in the case of SN Ib 2005bf, although they have velocities comparable to those of SN 2005bf. The whole evolution of the bolometric light curve is well reproduced by the explosion of a massive (Mej = 7.8 M⊙), He-poor star characterized by a double-peaked 56Ni distribution, a total 56Ni mass of 0.59 M⊙, and an explosion energy of 2.2 × 1051 erg. Alternatively, a normal SN Ib/c explosion (M(56Ni) = 0.11 M⊙, EK = 0.2 × 1051 erg, Mej = 1 M⊙) can power the first peak while a magnetar, with a magnetic field characterized by B = 5.0 × 1014 G, and a rotation period of P = 18.1 ms, provides energy for the main peak. The early g-band light curve can be fit with a shock-breakout cooling tail or an extended envelope model from which a radius of at least 30 R⊙ is obtained. Conclusions. We presented a scenario where PTF11mnb was the explosion of a massive, He-poor star, characterized by a double-peaked 56Ni distribution. In this case, the ejecta mass and the absence of He imply a large ZAMS mass (~85 M⊙) for the progenitor, which most likely was a Wolf-Rayet star, surrounded by an extended envelope formed either by a pre-SN eruption or due to a binary configuration. Alternatively, PTF11mnb could be powered by a SE SN with a less massive progenitor during the first peak and by a magnetar afterward.

The Light Variation and the Orbital Elements of AM Leonis = ADS 8024 A

1965 ◽  
Vol 5 ◽  
pp. 177
Author(s):  
L. Binnendijk
Keyword(s):  
Light Curve ◽  
Light Variation ◽  
National Observatory ◽  
Orbital Elements ◽  
Primary Minimum ◽  
Visual Component ◽  
Total Eclipse ◽  
Photometric Elements

AbstractThe star was followed photoelectrically in two colors through five consecutive nights in 1968 at Kitt Peak National Observatory. The light of the fainter visual component (a physical companion) was excluded. At primary minimum the system undergoes a total eclipse lasting 25 min. New internally consistent elements have been derived. A subluminous region on the larger star can be located. The previous light curve by Abrami leads to the same geometrical elements but to different photometric elements even when freed from the light of the distant companion.The paper appeared inAstron. J.74, 1031 (1969).

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