Nova Muscae Research Articles

Compton Backscattered Annihilation Radiation and the Mass of Nova MUSCAE

Assuming a dynamic model of accretion disks around a compact source, we calculate the spectrum of Compton scattered annihilation line emission from the disks, as a function of the location of the annihilation source as well as the observing angles and disk geometries. We show that spectral characteristics of the back-scattered spectra of the annihilation line, such as the intensity and position of the linelike feature, can provide new diagnostics of the innermost regions of accretion disks around compact objects. From comparisons of our Monte Carlo simulations and the spectrum observed from Nova Muscae, we find that the inclination angle of the accretion disk is 68° (+15°, −14°), implying a central black hole mass of about 5.0 (+2.0, −0.7) M ○.

An interpretation of the narrow positron annihilation feature from X-ray nova MUSCAE 1991

The physical mechanism responsible for the narrow redshifted positron annihilation gamma-ray line from the X-ray nova Muscae 1991 is studied. The orbital inclination angle of the system is estimated and its black hole mass is constrained under the assumptions that the annihilation line centroid redshift is purely gravitational and that the line width is due to the combined effect of temperature broadening and disk rotation. The large black hole mass lower limit of 8 solar and the high binary mass ratio it implies raise a serious challenge to theoretical models of the formation and evolution of massive binaries.

Detection of supersoft X-ray emission from GQ Muscae nine years after a nova outburst

GQ MUS (Nova Muscae 1983) was the first classical nova from which X-rays were detected during outburst1'2. Those Exosat observations were consistent with thermonuclear burning on the surface of a white dwarf emitting 1037–1038 erg s−1 at (3.0–3.5) × 105 K or with shocked circumstellar material emitting 1035 erg s−1 by thermal bremsstrahlung at 107 K. Here we report the detection by the Rosat satellite3 of GQ Mus as a very soft black-body-like source. If the observed X-ray flux is being radiated at the Eddington luminosity (1038 erg s−1) from a one-solar-mass white dwarf, its effective temperature must be ∼3.5 × 105 K. We conclude that the white dwarf is burning hydrogen-rich material near its surface. GQ Mus is, however, the only one of 26 recent novae detected in the all-sky Rosat survey; this suggests that either most novae eject all their accreted material during outburst, or GQ Mus is now burning recently accreted material. GQ Mus appears identical to the supersoft X-ray sources CAL83, CAL87 and RX J0527.8–6954 (ref. 4), lending support to the suggestion that these sources are white dwarfs accreting and burning material from a companion5.

Another canonical time variation of X-rays from black hole candidates in the very high flare state?

An X-ray nova, Nova Muscae 1991 or GS 1124-68, was observed with the LAC on board Ginga. On 1991 January 22, 7 days after its X-ray maximum, the same time variations were discovered as those observed in GX 339-4 at its near-flare maximum. The phase lags between different energy X-rays showed a peculiar large and broad peak, which was the same as that observed in GX 339-4. Shapes of the power spectrum density functions were similar, and indices of the power-law component of the X-ray energy spectra were the same

Synchrotron Bubbles and Radio Transients

AbstractWe discuss a generalisation of the synchrotron bubble model which has been applied to short-lived radio transients which can peak and decay over just a few days. The assumptions of the simple model imply that when the flux is increasing with time, it must also be an increasing function of frequency. Observations of two recent radio transients, Nova Muscae 1991 and the Galactic Centre Transient, include the first data showing such a rising phase, and in both cases the radio flux was a decreasing function of frequency during the observed rising phases. Thus the simple synchrotron bubble model is inadequate, at least for these events. A fundamental feature of the simple model is the assumption that the process accelerating the radiating electrons ceases before the radio emission can escape. We relax this assumption by including an injection of electrons, with a constant energy spectrum, into the synchrotron bubble.

Evidence for a black hole in the X-ray binary Nova MUSCAE 1991

view Abstract Citations (127) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for a Black Hole in the X-Ray Binary Nova MUSCAE 1991 Remillard, Ronald A. ; McClintock, Jeffrey E. ; Bailyn, Charles D. Abstract Optical photometry and spectroscopy of the X-ray Nova Muscae 1991 in quiescence reveal an orbital period of 10.398 +/- 0.014 hr and an absorption-line velocity curve consistent with a sinusoidal modulation at a half-amplitude of 409 +/- 18 km/s. The spectral type of the secondary star is in the range K0 V to K4 V. The value of the mass function, 3.1 +/- 0.4 solar mass, is a conservative lower limit on the mass of the compact primary and suggests that the primary is a black hole. Further considerations of the binary inclination angle and the mass of the secondary strengthen the black hole model. The folded light curves in the I band and the B + V band resemble ellipsoidal variations, with an additional brightening near one of the maxima in the B + V band. The orbital period is 1.4 percent shorter than the photometric period observed during outburst, as expected if the outburst modulations are analogs of 'superhumps' in dwarf novae. In quiescence, the optical properties of the X-ray binary Nova Muscae 1991 bear a striking resemblance to the black hole binary A0620-00, which extends the basis of similarity that was demonstrated during outburst at X-ray and optical wavelengths. Publication: The Astrophysical Journal Pub Date: November 1992 DOI: 10.1086/186628 Bibcode: 1992ApJ...399L.145R Keywords: Black Holes (Astronomy); K Stars; Novae; X Ray Binaries; Absorption Spectra; Light Curve; Stellar Mass; Stellar Models; Stellar Spectrophotometry; Astrophysics; BLACK HOLE PHYSICS; STARS: BINARIES: SPECTROSCOPIC; X-RAYS: STARS full text sources ADS | data products SIMBAD (13)

The Hubble Space Telescope observations of X-ray nova MUSCAE 1991 and its spectral evolution

Hubble Space Telescope Faint Object Spectrograph (FOS) Faint Object Camera (FOC) and observations of Nova Muscae 1991 obtained on May 14-15, 1991 are presented and discussed. A nearly featureless continuum with broad 2200 A absorption feature and no Balmer jump is found. The FOS spectrum is modeled, including previous multiepoch IUE, optical, and X-ray data using a simple blackbody accretion disk model. It is found that the mass transfer rate decays exponentially with a characteristic time of about 43 days. The cooling front predicted by the disk instability model should have been observable, but was not seen.

Discovery and X-ray properties of GS 1124 - 683 (= Nova Muscae)

view Abstract Citations (54) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery and X-Ray Properties of GS 1124-683 (=Nova Muscae) Kitamoto, Shunji ; Tsunemi, Hiroshi ; Miyamoto, Sigenori ; Hayashida, Kiyoshi Abstract The intensity and spectral evolution of the bright X-ray nova GS 1124 -683, observed with the All Sky Monitor from January 5 to the end of August, 1991, are presented. The spectra are roughly represented by a two-component model consisting of a power law and a thermal (disk-blackbody or blackbody) component. In its rising stage, the power-law component was dominant, and the thermal component gradually increased with temperature and emission area. In the decay phase, the power-law component decreased rapidly, whereas the thermal component decayed exponentially with a time constant of 31.2 +/-0.1 days. Some implications of the accretion phenomenon during the X-ray nova activity are discussed. Publication: The Astrophysical Journal Pub Date: August 1992 DOI: 10.1086/171614 Bibcode: 1992ApJ...394..609K Keywords: Black Holes (Astronomy); Novae; X Ray Stars; Ginga Satellite; Light Curve; Spaceborne Astronomy; Stellar Evolution; Stellar Models; Stellar Spectra; Astrophysics full text sources ADS | data products SIMBAD (7)

Periodic variability in the optical counterpart of X-ray Nova MUSCAE 1991

Analysis of over 1000 CCD images of the optical counterpart of the black hole candidate Nova Muscae 1991, taken 3-5 months after the initial outburst, reveal the existence of a luminosity hump of about 0.2 mag which recurs every 10.5 hr. This period presumably either is, or is closely related to, the orbital period, which is thus similar to that of the confirmed black hole system A0620 - 00. The light-curve shape, the lack of significant color variations, and marginal evidence for a change in the recurrence period suggest that the luminosity humps in Nova Muscae may be related to the superhump phenomenon in the SU UMa subclass of dwarf novae. Other implications of the analogy between soft X-ray transients and dwarf novae are discussed.

X-Ray Novae and Related Systems

Accretion disk thermal instability models have been successful in accounting for the basic observations of dwarf novae and the steady behavior of nova-like systems. Models for the dwarf-nova like variability of the old nova and intermediate polar GK Per give good agreement with the burst amplitude, profile and recurrence time in the optical and UV. A month-long “precursor plateau” in the UV is predicted for the expected 1992 outburst prior to the rise to maximum in the optical and UV. The models for the time scales of the outbursts and corresponding UV spectra at maximum are consistent with the inner edge of the accretion disk being essentially constant between quiescence and outburst and a factor of four larger than the corotation radius. These conclusions represent a challenge to the standard theory of magnetic accretion. Disk instability models have also given a good representation of the soft X-ray and optical outbursts of the X-ray novae A0620-00 and GS2000+25. Formation of coronae above the disk, heated by magneto-acoustic flux from the disk, may account for the temporal and spectral properties of the hard X-ray and gamma ray emission of related sources such as Cyg X-1, GS 2023+33 (V404 Cyg), 1E 1740.7-2942 (the “Galactic Center” Einstein Source), and GS 1124-683 (Nova Muscae).

Evidence for a black hole in the X-ray nova Muscae 1991

X-RAY novae form a subclass of low-mass X-ray binaries, which typically consist of a neutron star accreting material from a low-mass, late-type companion. In a few cases, however—notably A0620–00 (ref. 1)—, the accreting object may be a black hole. The detection and study of the optical counterpart is then of great importance in understanding the origin of the X-ray emission and the nature of the companion. We report here the discovery of a new X-ray nova, Nova Muscae 1991, which we found in a search for the optical counterpart of the new transient X-ray source GRS1121–68. The optical position, light-curve and early spectral development of the outburst support the identification of Nova Muscae 1991 as a binary, and similarities with A0620–00 (known optically as V616 Mon) in its early evolutionary stages led us to classify Nova Muscae 1991 as a candidate black-hole binary.

Measurements of Outburst Characteristics, Temperatures, Densities and Abundances in the Ejecta of Nova Muscae 1983

We present results for IUE, optical and IR observations of Nova Muscae 1983, from early outburst to January 1986 obtained by the European IUE Target of Opportunity Team. A detailed description of the data will appear elsewhere (Hassall et al., 1989), but here we summarise the most important results.The outburst lightcurve initially indicated a fast speed class for this nova, but was later characterised by a rather slow optical decline with two or more secondary outbursts with sudden doubling of the bolometric flux. In Figure 1, we show the contributions of X-ray, UV, optical and IR to the total luminosity for 1200 days following outburst, assuming a distance of 4.3kpc and an interstellar extinction E(B-V)=0.5. In the absence of dust formation, first the UV and later the X-ray flux (Ögelman et al, 1984) dominate the radiative energy late into the nebular phase. There was a plateau stage lasting about 500 days, with a bolometric luminosity of ~ 1038ergs s−1 near the Eddington limit. The secondary outbursts were thus super-Eddington. We estimate a total outburst energy (including kinetic and gravitational potential energy of the ejecta) of ~ 5·l046 ergs, corresponding to a mass of ~ 4·10−6Mº of hydrogen burnt in the thermonuclear runaway.

The photometric period of Nova MUSCAE 1983

view Abstract Citations (48) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Photometric Period of Nova MUSCAE 1983 Diaz, M. P. ; Steiner, J. E. Abstract The discovery of a photometric period of 85.5 minutes in GQ Mus (Nova Muscae 1983) is reported. Such a value for the orbital period is the shortest known for classical novae and the second to be discovered below the period gap. On the basis of the photometric and spectroscopic behavior, it is suggested that this star may belong to the class of AM Her objects. Publication: The Astrophysical Journal Pub Date: April 1989 DOI: 10.1086/185415 Bibcode: 1989ApJ...339L..41D Keywords: Astronomical Photometry; Novae; Orbits; Bursts; Hercules Nova; Astrophysics; PHOTOMETRY; STARS: NOVAE full text sources ADS | data products SIMBAD (5)

Exosat observations of X-rays from classical novae during outburst stage

The initial discovery of soft X-rays from Nova Muscae 1983 was followed by eight additional observations of the three brightest novae whose outburst stage coincided with the lifetime ofEXOSAT satellite; namely three more observations of Nova Muscae 1983, three observations of Nova Vulpeculae 1984#1 (PW Vul), and two observations of Nova Vulpeculae 1984#2. Through these observations we sampled the soft X-ray light curve of classical novae from optical maximum to ∼900 days after. The observations seem best explained by the constant bolometric luminosity model of a hot white dwarf remnant. Although the measurements suffer from limited statistics, very broad energy bandpass, and incomplete sampling of any single nova, their constraints on the theories of nova outburst are significant. One constraint is that the lifetime of the white dwarf remnant in Nova Muscae 1983 is ∼2 to 3 years, which leads to the conclusion that the burned envelope massM burn should be of the order of $$10^{ - 6} \left( {\frac{{10^{38} erg s ^{ - 1} }}{{L_{burn} }}} \right)M_ \odot $$ . The second constraint is that the maximum temperature, of the white dwarf remnant should approximately be within 200 000 K to 400 000 K. We estimate that a white dwarf remnant evolving like the central star of a planetary nebula, with core mass of 0.8 to 0.9M ⊙, core luminosity of ∼2×104 L ⊙, and envelope mass of 10−6 M ⊙, can explain the general characteristics of the X-ray measurements for Nova Muscae 1983. In order to have ≥1.1M ⊙ core mass, estimated from the early observations of bolometric luminosity in the UV to infrared range, a wind withM≤5×10−7 M ⊙ yr−1 appears to be necessary. The few observations of Nova Vulpeculae 1984 #1 and Nova Vulpeculae 1984#2, during the first year after outburst, give a risetime and intensity that is consistent with a constant bolometric luminosity model.

Exosat Observations of X-Rays from Classical Novae during Outburst Stage

AbstractThe initial discovery of soft X-rays from Nova Muscae 1983 was followed by eight additional observations of the three brightest novae whose outburst stage coincided with the lifetime of EXOSAT satellite; namely three more observations of Nova Muscae 1983, three observations of Nova Vulpeculae 1984 # 1 (PW Vul), and two observations of Nova Vulpeculae 1984 # 2. Through these observations we sampled the soft X-ray light curve of classical novae from optical maximum to ~ 900 days after. The observations seem best explained by the constant bolometric luminosity model of a hot white dwarf remnant. Although the measurements suffer from limited statistics, very broad energy bandpass, and incomplete sampling of any single nova, their constraints on the theories of nova outburst are significant. One constraint is that the lifetime of the white dwarf remnant in Nova Muscae 1983 is ~ 2 to 3 years, which leads to the conclusion that the burned envelope mass Mburn should be of the order of . The second constraint is that the maximum temperature, of the white dwarf remnant should approximately be within 200 000 K to 400 000 K. We estimate that a white dwarf remnant evolving like the central star of a planetary nebula, with core mass of 0.8 to 0.9 M⊙, core luminosity of ~ 2 × 104L⊙, and envelope mass of 10−6M⊙, can explain the general characteristics of the X-ray measurements for Nova Muscae 1983. In order to have ≥ 1.1 M⊙ core mass, estimated from the early observations of bolometric luminosity in the UV to infrared range, a wind with Ṁ ≤ 5 × 10−7M⊙yr−1 appears to be necessary. The few observations of Nova Vulpeculae 1984 # 1 and Nova Vulpeculae 1984 # 2 , during the first year after outburst, give a risetime and intensity that is consistent with a constant bolometric luminosity model.

X-ray and optical observations of Nova Muscae 1983 during its nebular stage

The detection of X-rays from Nova Muscae 1983 (discovered on January 18, 1983) constitutes the first detection of X-rays from a classical nova during outburst. X-ray observations were carried out on 1984 April 20 and July 14 when Nova Mus had entered the nebular stage. During both observations no significant flux was observed with the medium energy detectors (2-50 keV). The source was detected with the low energy detector (.04-2 keV) using 3000 A Lexan and Parlene- N-Aluminium filters; counting rates of (3.4 ± 1.2) x 103 and (3.7 ± 1.2 x 10~3 counts/sec were measured with the respective filters. The source was detected again on July 14 with about the same intensity. Either a shocked shell of circumstellar gas emitting 107 thermal bremsstrahlung at 1035 erg/sec intensity or a white dwarf remnant emitting 3.5x 105 blackbody radiation at 1037 erg/sec luminosity are compatible with the measurements.

The detection of X-rays from Nova MUSCAE 1983 with the EXOSAT satellite

view Abstract Citations (48) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The detection of X-rays from nova MUSCAE 1983 with the EXOSAT satellite. Oegelman, H. ; Beuermann, K. ; Krautter, J. Abstract Nova Muscae 1983, a fast classical nova, was discovered on January 18, 1983, by Liller (1983). The present investigation is concerned with a study of this star on the basis of X-ray observations which have been conducted with the low- and medium-energy detectors of the Exosat satellite on April 20, 1984. The measured data are combined with other measurements, and a comparison with nova models is conducted with the objective to obtain information regarding the nature of the X-ray emission from Nova Muscae. It is concluded that there are basically two possibilities for explaining the soft X-ray observations. One explanation involves a shocked circumstellar gas under conditions including a temperature of approximately 10,000,000 K and a luminosity of approximately 10 to the 35th ergs/s. The other explanation is based on a white dwarf remnant at a surface temperature of approximately 350,000 K. The observations represent the first detection of X-rays from a classical nova during outburst, including the decline stage. Publication: The Astrophysical Journal Pub Date: December 1984 DOI: 10.1086/184391 Bibcode: 1984ApJ...287L..31O Keywords: Exosat Satellite; Novae; Satellite Sounding; Stellar Radiation; X Ray Sources; Bremsstrahlung; Thermal Radiation; White Dwarf Stars; Astronomy full text sources ADS | data products SIMBAD (1)