HM Sge Research Articles

The nature of classical symbiotic stars

The results of the optical and infrared observations of classical symbiotic stars Z and, CI Cyg, BF Cyg, AG Dra, AX Per, V443 Her, and YY Her are summarized. It is shown that the hot component of most classical symbiotic stars is a hot subdwarf and not a Main-Sequence star with an accretion disc. The energy source of its outbursts is the gravitational energy of the matter accreted from the cool component's surface. The cool component is a red giant filling the Roche lobe and having class II luminosity. In the intervals between outbursts the hot component's luminosity may be determined by its own energy sources. It is probable that among classical symbiotic stars there are-in an insignificant quantity-systems in which the hot component is a Main-Sequence star with an accretion disc. In such systems eclipses of the hot source of radiation by the red giant must without fail occur and the hot component must be a yellow or red dwarf. The transition from a symbiotic nova (V1016 Cyg, HM Sge, and RR Tel) to a classical symbiotic nova takes place at the moment when the cool component's size is approaching the size of the Roche lobe, resulting in a sharp increase of the accretion rate of its matter onto the hot component. The nonstationarity of this process leads to the appearance of nova-like outbursts on classical symbiotic stars' light curves.

X-ray emissions from symbiotic novae

view Abstract Citations (46) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray emissions from symbiotic novae. Kwok, S. ; Leahy, D. A. Abstract X-ray observations of three symbiotic novae made with the Einstein Observatory by Allen (1981) have been further analyzed. The observed spectra are consistent with thermal bremsstrahlung from circumstellar hot gas of about 10 to the 7th K. It is proposed that this hot region is the shocked gas resulting from the fast wind from the white dwarf component of the symbiotic nova colliding with the slow wind from the M giant component. The expected decline in X-ray luminosity as the shocked region expands is consistent with the monotonic decreasing X-ray fluxes from the youngest (HM Sge) to the oldest (RR Tel) member of the symbiotic novae. Publication: The Astrophysical Journal Pub Date: August 1984 DOI: 10.1086/162353 Bibcode: 1984ApJ...283..675K Keywords: Dwarf Novae; Stellar Activity; Symbiotic Stars; X Ray Sources; Bremsstrahlung; Heao 2; M Stars; Stellar Luminosity; Stellar Winds; X Ray Spectra; Astrophysics full text sources ADS | data products SIMBAD (3)

Evolution of the optical spectrum of HM Sagittae: 1977-1982

view Abstract Citations (33) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evolution of the optical spectrum of HM Sagittae : 1977-1982. Stauffer, J. R. Abstract High-resolution spectra have been obtained for HM Sge and V1016 Cygni, two prominent members of the RR Tel family of symbiotic stars. Gaussian fits were made to the emission lines present in those spectra in order to attempt a kinemaic separation of the different line-emitting regions expected in those stars. The dominant emission lines are attributed to an expanding, biconical shell created by the interaction of a high-velocity wind from the white dwarf with a preexisting, low velocity wind from the cool star. Twenty eight low-resolution spectra of HM Sge were obtained during the period 1977 June through 1982 June. Relative fluxes for emission lines in the 3800 - 8300 Å region have been derived from those spectra. Prior to 1979 August, the effective temperature of the hot star was less than 70,000K. By 1980 May, the temperature of the hot star had increased to 160,000K. A plausible model for the system is that the 1975 outburst of HM Sge resulted from a hydrogen flash in the accretion envelope of the white dwarf. The 1979 transition occurred when the wind from the white dwarf completed removal of that envelope, exposing the hotter core of the white dwarf. Publication: The Astrophysical Journal Pub Date: May 1984 DOI: 10.1086/162043 Bibcode: 1984ApJ...280..695S Keywords: Companion Stars; High Resolution; Red Giant Stars; Stellar Spectra; Visible Spectrum; White Dwarf Stars; Astronomical Catalogs; Emission Spectra; Line Spectra; Radiant Flux Density; Spectral Line Width; Stellar Envelopes; Stellar Evolution; Stellar Models; Stellar Winds; Astrophysics full text sources ADS | data products SIMBAD (2)

The radio history of HM Sagittae

The remarkable radio brightening of HM Sge over the period 1977 - 80 is documented at a number of frequencies. The data, together with an angular size measurement obtained at the VLA, are used to assess various models of the radio-emitting region. Simple models are not compatible with both the radio data and the assumed luminosity distance.

Spectrophotometric observations of symbiotic stars and related objects

Calibrated optical spectrophotometric observations of 16 symbiotic and symbiotic-like objects are presented. The objects observed include Z And, T CrB, CH Cyg, CI Cyg, V1016 Cyg, V1329 Cyg, AG Dra, YY Her, RS Oph, XX Oph, AG Peg, AX Per, CL Sco, HM Sge, AS 289, and M1-2. Integrated emission-line intensities are tabulated for comparison with ultraviolet and infrared data, as well as with previous optical studies. The reddening to each of the objects is derived by assuming that Balmer lines are emitted in their case B recombination ratios. However, the values so derived are often systematically higher than reddening estimates from the ultraviolet 2200 A feature. Comparisons with the available data from other wavelength ranges are noted.

The outbursts of symbiotic novae

view Abstract Citations (77) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The outbursts of symbiotic novae. Kenyon, S. J. ; Truran, J. W. Abstract Possible conditions are discussed under which thermonuclear burning episodes in the hydrogen-rich envelopes of accreting white dwarfs give rise to outbursts similar in nature to those observed in the symbiotic stars Ag Peg, RT Ser, RR Tel, AS 239, V1016 Cyg, V1329 Cyg, and HM Sge. In principle, thermonuclear runaways involving low-luminosity white dwarfs accreting matter at low rates produce configurations that evolve into A-F supergiants at maximum visual light and which resemble the outbursts of Rr Tel, RT Ser, and AG Peg. Very weak, nondegenerate hydrogen shell flashes on white dwarfs accreting matter at high rates do not produce cool supergiants at maximum, and may explain the outbursts in V1016 Cyg, V1329 Cyg, and HM Sge. The extremely slow outbursts of symbiotic novae appear to be typical of accreting white dwarfs in wide binaries, which suggests that the outbursts of classical novae may be accelerated by the interaction of the expanding white dwarf envelope with its close binary companion. Publication: The Astrophysical Journal Pub Date: October 1983 DOI: 10.1086/161367 Bibcode: 1983ApJ...273..280K Keywords: Binary Stars; Bursts; Dwarf Novae; Stellar Mass Accretion; Thermonuclear Reactions; White Dwarf Stars; F Stars; Stellar Evolution; Stellar Models; Supergiant Stars; Astrophysics full text sources ADS | data products SIMBAD (7)

EMISSION-LINE PROFILES FOR SELECTED PLANETARY NEBULAE AND SYMBIOTIC STARS V1016 CYGNI AND HM SAGITTAE.

ABSTRACT Emission-line profiles are given for twelve planetary nebulae in Hα and for seven in [O III] λ5007, for four symbiotic stars in Hα, and for the emission objects V1016 Cyg and HM Sge in both Hα and λ5007. Expansion velocities generally between 10 and 30 km s-1 are estimated for the planetary nebulae; the profiles are similar in Hα and λ5007 in most cases for which both are available. The profiles for V1016 Cyg, HM Sge, and the symbiotic stars are much wider and in most cases exhibit variability and multiple components. In particular, the variations in the line profiles of V1016 Cyg and HM Sge are displayed and described.

IUE observations of proto-planetary and variable planetary nebulae. I - V1016 Cygni, HM Sagittae, and HBV 475. II - A search for variability in IC 4997 and NGC 6905

view Abstract Citations (47) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS IUE observations of proto-planetary nebulae. I. V1016 Cyg, HM SGE andHBV 475. Feibelman, W. A. Abstract The IUE satellite has undertaken UV observations of the proto-planetary nebulae V1016 Cyg, HM Sge, and HBV 475, yielding emission line fluxes, line ratios, line profiles, electron densities, and distances from these objects. While levels of increasing excitation and ionization as a function of time are shown by the data for the first two nebulae, the trend for HBV 475 is found to lead in the opposite direction. The formation of a shell is suggested by dramatic changes in the HM Sge UV line profiles over the last four years, including the disappearance of W-R features and the incipient splitting of the semi-forbidden C III 1909 A line. An additional IUE search for UV variability in the planetary nebulae IC 4997 and NGC 6905 has yielded emission line fluxes, line ratios and profiles, and central star temperatures, as well as stratification effects data for several ions in NGC 6905 Publication: The Astrophysical Journal Pub Date: July 1982 DOI: 10.1086/160105 Bibcode: 1982ApJ...258..548F Keywords: Emission Spectra; Iue; Line Spectra; Planetary Nebulae; Protoplanets; Ultraviolet Spectra; Electron Density (Concentration); Ionization; Molecular Excitation; Stellar Temperature; Astronomy full text sources ADS | data products SIMBAD (6) MAST (1) INES (1) Related Materials (1) Part 2: 1982ApJ...258..562F

Visible and/or near infrared spectral variations of v1016 Cygni, HM sagittae and MWC 349

The recent spectral evolution of the three peculiar emission-line objects with IR excess V1016 Cyg, HM Sge, and MWC 349 is described, on the basis of data obtained at the Asiago (blue and red spectral regions) and Haute Provence (near infrared) Observatories. In the near infrared spectral region, details are given concerning the data briefly described in IAU Circular No. 3498 (Andrillat and Swings, 1980).

X-ray observations of symbiotic stars

AbstractObservations are reported of 19 symbiotic stars made with the imaging proportional counter of the Einstein Observatory. Three of the objects (HM Sge, V 1016 Cyg and RR Tel) were detected as soft X-ray sources. All three have shown slow-nova eruptions in the past 40 years. The data are interpreted as support of a model for slow novae involving thermonuclear events on white dwarfs which accrete from M giant companions. Symbiotic stars in their steady state, not being detected X-ray sources, are presumed to be powered by the accretion process alone.

Spectral evolution of HM Sagittae in the ultraviolet

We have observed the ultraviolet spectrum of HM Sge with the International Ultraviolet Explorer during 1978-1980.

X-ray observations of symbiotic stars

Observations are reported of 19 symbiotic stars made with the imaging proportional counter of the Einstein Observatory. Three of the objects (HM Sge, V 1016 Cyg and RR Tel) were detected as soft X-ray sources. All three have shown slow-nova eruptions in the past 40 years. The data are interpreted as support of a model for slow novae involving thermonuclear events on white dwarfs which accrete from M giant companions. Symbiotic stars in their steady state, not being detected X-ray sources, are presumed to be powered by the accretion process alone.

Near Infrared Spectroscopy of Possible Precursors to Planetary Nebulae - Hm-Sagittae

view Abstract Citations (20) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Near-infrared spectroscopy of possible precursors to planetary nebulae : HM Sagittae. Thronson, H. A. ; Harvey, J. M. Abstract Two 1.5-2.3 μm spectra of the candidate protoplanetary nebula HM Sge are presented and discussed. A number of the Brackett series of hydrogen are seen in emission, allowing an estimate of source excitation and extinction. In addition, one spectrum shows the photospheric absorption features that are characteristic of a late-type giant star. The second spectrum shows no such features. Using previous models and observations, the infrared line-emitting region is found to be extremely small-in agreement with the idea that the source has recently begun a period of rapid mass loss or exchange. It is suggested that the recently observed brightening of HM Sge was due to partial unveiling of the source due to the motion of a dusty shell. Such an effect may also explain the current small amplitude variation in visual extinction. The object is found to lie on the Harman-Seaton sequence, as appropriate for young, evolving protoplanetaries. A number of the observations are in agreement with a model of planetary nebula formation, although the total nebular mass appears to be at least three orders of magnitude below that found in planetary nebulae. A search for radio 12CO emission was unsuccessful, consistent with HM Sge being oxygen rich. Publication: The Astrophysical Journal Pub Date: September 1981 DOI: 10.1086/159183 Bibcode: 1981ApJ...248..584T full text sources ADS | data products SIMBAD (5)

Is a stellar wind inherent in WR–stars throughout the whole of their evolution?

In addition to certain manifestation of a stellar wind during steady states of WR-stars that we have heard here about I have two notes on their extremal stages of evolution which may be also connected to such a hydrodynamical event.The first note. There is a pecular object, HM Sge that had brightened for several magnitudes during several months. It has a strong emission spectrum that is similar to a planetary nebula spectrum in general, and it was suggested that we register a planetary nebula birth. However, in Crimea we have found that a total width of H-alfa emission line is ~ 2000 Km/sec and a central part of its profile is asymmetric significantly. These features exclude a genetic, relationship between HM Sge and Planetary nebulae.

HM Sagittae as a young planetary nebula

HM Sagittae is suggested to be a very young planetary nebula recently transformed from a red-giant star through continuous mass loss. The observational data for HM Sge have been analyzed in terms of the interacting stellar wind model of planetary nebula formation. The model is in accord with virtually all the spectral data available--radio, optical, and infrared--as well as with the remarkable brightening of HM Sge observed in 1975. In particular, all three gaseous components predicted by the model are observed in the optical spectrum. The density in the newly formed shell is found to be at least 5 x 10/sup 7/ cm/sup -3/, a value considerably higher than that found by the conventional analysis, which assumes a single-component homogeneous nebula. The radio spectrum is dominated by free-free emission from the remnant red-giant wind. The infrared spectrum suggests the presence of two dust components, one consisting of silicate grains left over from the red-giant stage and the other of grains newly formed after the 1975 brightening. The low observed shell mass is consistent with the interacting stellar wind model but is not consistent with the conventional sudden-ejection model of planetary nebula formation.

Infrared spectra of HM Sagittae and V1016 Cygni

Spectrophotometry of HM Sge from 2 to 13 microns is presented along with 2 to 4-micron spectrophotometry of V1016 Cyg. From 2.5 to 8 microns, the spectrum of HM Sge can be represented by a 950-K blackbody, and a strong silicate emission feature is seen from 8 to 13 microns. Both HM Sge and V1016 Cyg show evidence of CO absorption at 2.3 microns. It is suggested that the infrared radiation from these objects arises from a combination of emission by optically thin dust and by the reddened photosphere of a cool star.

EMISSION-LINE WIDTHS IN THE SPECTRUM OF THE POSSIBLE PROTO-PLANETARY NEBULA HM SAGITTAE.

ABSTRACT We have observed the new emission-line object HM Sge in the region of lambda 6200 to lambda 6700 at 6 A mm to the -1. The line profiles show a huge disparity in width ranging from 35 km sec to the -1 for N II to 1700 km sec to the -1 for H alpha. We suggest the interpretation that the great width of H alpha is due to electron scattering in the central source while most of the other lines are broadened kinematically as part of the expanding planetary nebula. The very narrow N II lines may be formed in a larger region that was formerly the expanding envelope of a cool star.

Optical and infrared observations of the new emission-line object HM Sagittae

view Abstract Citations (46) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Optical and infrared observations of the new emission-line object HM Sagittae. Davidson, K. ; Humphreys, R. M. ; Merrill, K. M. Abstract The blue spectrum and photometry from 0.4 to 12 ttm of HM Sge in 1977 June are discussed. These data permit the estimation of various physical parameters of interest including size scales, gas densities, a few ionic abundances, and the total energy flux. The object may be a symbiotic star; the possible relationship with planetary nebulae is not clear. Subject headings: stars: combination spectra - stars: emission4ine - stars: individual Publication: The Astrophysical Journal Pub Date: February 1978 DOI: 10.1086/155899 Bibcode: 1978ApJ...220..239D Keywords: Emission Spectra; Infrared Radiation; Light (Visible Radiation); Stellar Spectra; Gas Density; Hot Stars; Photoionization; Photometry; Planetary Nebulae; Astronomy; Emission-Line Stars:Infrared Spectra; Emission-Line Stars:Spectra; Infrared Spectra:Symbiotic Stars full text sources ADS | data products SIMBAD (6)

RECENT NOVA AND VARIABLE-STAR RESEARCH WITH THE HARVARD PHOTOGRAPHIC COLLECTION.

ABSTRACT This report contains a summary of research conducted in 1976 and early 1977 with the Harvard plate stacks on novae, possihle novae, and an emission variahle. Light curves for He 3-1481 and HM Sge are included, as well as the results of searches for earlier outbursts of recent novae. Key words: novae-emission variahles

Current Status of HM Sge Measurements

Current Status of HM Sge Measurements