scholarly journals Confirmation of the Luminous Blue Variable Status of MWC 930

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
A. S. Miroshnichenko ◽  
N. Manset ◽  
S. V. Zharikov ◽  
J. Zsargó ◽  
J. A. Juárez Jiménez ◽  
...  
Keyword(s):  
Emission Line ◽  
Terminal Velocity ◽  
High Luminosity ◽  
Luminous Blue Variables ◽  
Near Ir ◽  
Photometric Observations ◽  
Emission Line Spectrum ◽  
Bona Fide ◽  
Luminous Blue Variable

We present spectroscopic and photometric observations of the emission-line star MWC 930 (V446 Sct) during its long-term optical brightening in 2006–2013. Based on our earlier data we suggested that the object has features found in Luminous Blue Variables (LBV), such as a high luminosity (~3 105 L⊙), a low wind terminal velocity (~140 km s−1), and a tendency to show strong brightness variations (~1 mag over 20 years). For the last~7 years it has been exhibiting a continuous optical and near-IR brightening along with a change of the emission-line spectrum appearance and cooling of the star’s photosphere. We present the object’sV-band light curve, analyze the spectral variations, and compare the observed properties with those of other recognized Galactic LBVs, such as AG Car and HR Car. Overall we conclude the MWC 930 is a bona fide Galactic LBV that is currently in the middle of an S Dor cycle.

scholarly journals Photometry of AM Her Stars – Line and Continuum Emission

1979 ◽  
Vol 53 ◽  
pp. 324-328
Author(s):  
Paula Szkody
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Main Sequence ◽  
Close Binary ◽  
Line Spectrum ◽  
Continuum Emission ◽  
Late Type ◽  
Emission Line Spectrum ◽  
Orbital Periods

The 4 known AM Her stars or polars (AM Her, ANUMa, W Pup, and 2A0311-227) are characterized by large circular polarizations of 10-35%, (Tapia 1977a, b, Krzeminski and Serkowski 1977), an emission line spectrum with strong H and He lines (Crampton and Cowley 1977, Greenstein et al. 1977), complex photometric variations (Szkody 1978, Priedhorsky and Krzeminski 1978, Warner & Nather 1972), long term high and low states and short orbital periods (80-180 min.). Models of these systems envision a close binary containing a magnetic white dwarf primary (B ~ 108G) and late type main sequence secondary transferring material into an accretion funnel over one or both poles of the white dwarf (Stockman et al. 1977, Lamb & Masters 1979, Liebert et al. 1978).

scholarly journals The enigmatic binary system HD 5980

2019 ◽  
Vol 486 (1) ◽  
pp. 725-742 ◽  
Author(s):  
D John Hillier ◽  
Gloria Koenigsberger ◽  
Yaël Nazé ◽  
Nidia Morrell ◽  
Rodolfo H Barbá ◽  
...  
Keyword(s):  
Mass Loss ◽  
Emission Line ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Phase Dependence ◽  
Wind Speeds ◽  
Line Intensities ◽  
Orbital Phase ◽  
Emission Line Spectrum ◽  
Luminous Blue Variable

Abstract The Small Magellanic Cloud multiple system HD 5980 contains a luminous blue variable (LBV) that underwent a major eruption in 1994, and whose current spectrum is that of a hydrogen-rich Wolf–Rayet (WR) star. Since the eruption, the wind mass-loss rate has been declining while wind speeds have been steadily increasing. Observations obtained in 2014 when Star A (the LBV) eclipses Star B indicate that the fitted mass-loss rate and luminosity have reached the lowest values ever determined for such spectra: $\dot{M}$  = 4.5 × 10−5$\mathrm{M}_\odot \, \hbox{yr}^{-1}$, L  = 1.7 × 106 L⊙. In addition, the radius of the LBV’s continuum-emitting region is similar to that derived from the eclipse light curves of the late 1970s. Hence, it appears to have attained a similar ‘low’ state to that of the late 1970s. While a good fit to the emission spectrum is obtained using a cmfgen model, there are discrepancies in the UV. In particular, the extent of the observed absorption profiles is ∼1000 km s−1 greater than predicted by the emission-line intensities. Further, HST UV observations obtained in 2016, when Star A is eclipsed by Star B, show unusual P Cygni profiles that are not easily explained. Surprisingly the 2016 emission-line spectrum is similar to that at the opposite eclipse obtained in 2014. The complex UV profiles are likely to arise as a consequence of the dynamics of the wind–wind collision and radiative braking, both of which will cause significant departures from spherical symmetry, and have a strong orbital phase dependence. However, other scenarios, such as intrinsically aspherical winds, cannot be ruled out.

scholarly journals BI Crucis

1988 ◽  
Vol 103 ◽  
pp. 297-298
Author(s):  
A. Altamore ◽  
C. Rossi ◽  
R. Viotti
Keyword(s):  
Emission Line ◽  
Line Spectrum ◽  
Cool Component ◽  
Iras Source ◽  
Emission Line Spectrum ◽  
Vibration Rotation ◽  
Absorption Features ◽  
Co Emission ◽  
The Continuum

BI Crucis is a 12 mag star whose optical spectrum is characterized by a red continuum and variable emission line spectrum (Allen 1974, Henize and Carlson 1980, Whitelock et al. 1983). In order to investigate its symbiotic character on 18 February 1983 we have obtained at the 1.5m ESO telescope a 59 Å/mm spectrogram of the 5700-6900 Å region. BI Cru displayed a very rich emission line spectrum with very strong Hα. and prominent HeI (5876 and 6678Å) lines. Several FeII lines are also present which appear optically thick (Figure 1). A few absorption features (NaI, 6269-84) of interstellar origin are present. However, we find no trace of TiO bands (or of neutral atoms) in spite of Allen’s (1974) finding, but in agreement with Whitelock et al. (1983). Allen (priv. comm.) remarks that in his spectrum there are slight ‘waves’ in the continuum that looked like TiO absorptions. Thus the symbiotic nature of BI Cru is mostly based on its long term IR variability (T≅280 d, Whitelock et al. 1983). They also found the first overtone vibration rotation band of CO at 2.3 μm in emission. The CO emission band was recently resolved by McGregor et al. (1987). This is the first observation of CO in emission in a symbiotic object. The red continuum is more probably a highly reddened hot continuum. We note that a weak continuum is present in the LWR IUE image taken in March 1981 (Fig.2). This spectrum also shows a few emission lines of Mgll and FeII. BI Cru is also a strong IRAS source. Following the model of Kenyon et al. (1986) for D-type symbiotics, the cool component of BI Cru could be reddened by circumstellar dust. A high resolution ESO CAT/CES red spectrum shows Hα doubled by a central absorption extending from −38 to −290 km/s with respect to the center of the emission line which suggests the presence of intermediate velocity winds like in other symbiotic stars.

scholarly journals The Ionization of Novae Ejecta

1990 ◽  
Vol 122 ◽  
pp. 215-227
Author(s):  
R.E. Williams
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Line Spectrum ◽  
Ionized Gas ◽  
Grain Formation ◽  
Emission Line Spectrum ◽  
Pass Through

AbstractNovae ejecta pass through four distinct phases of evolution of the emission-line spectrum, caused by different ionization characteristics of the shell. These include a neutral (I), an auroral (II), a coronal (III), and a nebular (IV) phase. Photoionization from the contracting photosphere of the hot white dwarf is the source of the ionization, including the highly ionized coronal phase. Changing emission line ratios in certain novae that develop dust are caused by condensation of grains from the gas, and can be used to determine the composition of the dust. In V1370 Aql, substantial silicate grain formation appears to have taken place, probably within the ionized gas.

scholarly journals The unusual emission line spectrum of I Zw 1

2004 ◽  
Vol 2004 (IAUS222) ◽  
pp. 271-274
Author(s):  
Monique Joly ◽  
M.-P. Véron-Cetty ◽  
P. Véron
Keyword(s):  
Emission Line ◽  
Line Spectrum ◽  
Emission Line Spectrum

scholarly journals Long-Term Multicolour Photometry of the Young Stellar Objects FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cygni

2015 ◽  
Vol 32 ◽  
Author(s):  
S. I. Ibryamov ◽  
E. H. Semkov ◽  
S. P. Peneva
Keyword(s):  
Gulf Of Mexico ◽  
Young Stellar Objects ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Photometric Variability ◽  
The North ◽  
Dense Molecular Cloud ◽  
Photometric Observations ◽  
All Optical

AbstractResults from long-term multicolour optical photometric observations of the pre-main-sequence stars FHO 26, FHO 27, FHO 28, FHO 29, and V1929 Cyg collected during the period from 1997 June to 2014 December are presented. The objects are located in the dense molecular cloud L935, named ‘Gulf of Mexico’, in the field between the North America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to define the reasons for the observed brightness variations. The presented paper is a part of our long-term photometric study of the young stellar objects in the region of ‘Gulf of Mexico’.

scholarly journals The May 1985 Superoutburst of OY Carinae: II. Phase-Resolved IUE Spectroscopy and Exosat Observations

1987 ◽  
Vol 93 ◽  
pp. 371-376 ◽  
Author(s):  
B.J.M. Hassall ◽  
T. Naylor ◽  
G.T. Bath ◽  
P.A. Charles ◽  
G. Sonneborn ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Spectrum ◽  
X Ray ◽  
Dwarf Nova ◽  
Uv Emission ◽  
Emission Line Spectrum ◽  
Coronal Region

AbstractWe present ultraviolet and X-ray observations of the eclipsing SU UMa dwarf nova OY Car early in the decline from a superoutburst. From the UV emission line spectrum and lack of X-ray eclipse, we deduce the presence of an extended coronal region.

NGC 3516: The Long‐Term Variability of the Active Galactic Nucleus Emission‐Line and Absorption‐Line Regions

1999 ◽  
Vol 524 (2) ◽  
pp. 707-731 ◽  
Author(s):  
M. R. Goad ◽  
A. P. Koratkar ◽  
J. Kim‐Quijano ◽  
K. T. Korista ◽  
P. T. O'Brien ◽  
...  
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Active Galactic Nucleus

scholarly journals A CO EMISSION LINE FROM THE OPTICAL AND NEAR-IR UNDETECTED SUBMILLIMETER GALAXY GN10

2009 ◽  
Vol 695 (2) ◽  
pp. L176-L180 ◽  
Author(s):  
E. Daddi ◽  
H. Dannerbauer ◽  
M. Krips ◽  
F. Walter ◽  
M. Dickinson ◽  
...  
Keyword(s):  
Emission Line ◽  
Near Ir ◽  
Co Emission

scholarly journals Near-IR echelle spectroscopy of Class I protostars: Mapping Forbidden Emission-Line (FEL) regions in [FeII]

2002 ◽  
Vol 397 (2) ◽  
pp. 693-710 ◽  
Author(s):  
C. J. Davis ◽  
E. Whelan ◽  
T. P. Ray ◽  
A. Chrysostomou
Keyword(s):  
Emission Line ◽  
Class I ◽  
Near Ir ◽  
Echelle Spectroscopy
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