Emission-line widths in the spectrum of the possible proto-planetary nebula HM Sagittae

1978 ◽  
Vol 90 ◽  
pp. 36 ◽  
Author(s):  
G. Wallerstein
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Line Widths

scholarly journals Upper limits on the mass of supermassive black holes from STIS archival data

2007 ◽  
Vol 3 (S245) ◽  
pp. 233-234
Author(s):  
A. Beifiori ◽  
E. M. Corsini ◽  
E. Dalla Bontà ◽  
A. Pizzella ◽  
L. Coccato ◽  
...  
Keyword(s):  
Black Holes ◽  
Emission Line ◽  
Supermassive Black Holes ◽  
Archival Data ◽  
Early Type ◽  
Preliminary Results ◽  
Upper Limits ◽  
Nearby Galaxies ◽  
Line Widths

AbstractThe growth of supermassive black holes (SMBHs) appears to be closely linked with the formation of spheroids. There is a pressing need to acquire better statistics on SMBH masses, since the existing samples are preferentially weighted toward early-type galaxies with very massive SMBHs. With this motivation we started a project aimed at measuring upper limits on the mass of the SMBHs that can be present in the center of all the nearby galaxies (D < 100 Mpc) for which STIS/G750M spectra are available in the HST archive. These upper limits will be derived by modeling the central emission-line widths ([N II] λλ6548, 6583, Hα and [S II] λλ6716, 6731) observed over an aperture of ~01 (R < 50 pc). Here we present our preliminary results for a subsample of 76 bulges.

scholarly journals Variable Spectra of IC 4997 and NGC 6572

1993 ◽  
Vol 155 ◽  
pp. 488-488
Author(s):  
Siek Hyung ◽  
Lawrence H. Aller ◽  
Walter A. Feibelman
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
Line Intensity ◽  
Planetary Nebula ◽  
Radiative Flux ◽  
Gradual Decrease ◽  
High Dispersion ◽  
Echelle Spectrograph

Variability of the [OIII]4363/4340 H γ ratio in IC 4007 was established in 1956 by William Liller and L.H. Aller who attributed the changes to a gradual decrease of electron density with time. Subsequent 4363/4340 ratio fluctuations negated this explanation. Ferland pointed out that small changes in the radiative flux of the Planetary nebula nucleus (PNN) could explains the variations. Our pervious study emphasized IUE observations, here we compare high dispersion spectra obtained with the Hamilton Echelle Spectrograph with previous measurements to asses line intensity variations. Emission line variability in PNN spectra as noted by Mendez et al. (1988) and by other for HeII 4686 in NGC 6572 may offer significant clues. PNN 4686 appeared by 1990 in IC 4997. Possibly both of these PNN may be evolving into Wolf-Rayet objects, but this development does not necessarily imply that the nebular excitation will increase with time.

K emission-line widths and the solar chromosphere

Solar Physics ◽  
1971 ◽  
Vol 17 (2) ◽  
pp. 316-330 ◽  
Author(s):  
M. K. V. Bappu ◽  
K. R. Sivaraman
Keyword(s):  
Emission Line ◽  
Solar Chromosphere ◽  
Line Widths

scholarly journals Raman Scattering and the Hidden He II Emission Region in the Bipolar Planetary Nebula M2-9

2003 ◽  
Vol 209 ◽  
pp. 399-400
Author(s):  
Hee-Won Lee
Keyword(s):  
Raman Scattering ◽  
Emission Line ◽  
Planetary Nebula ◽  
Emission Lines ◽  
Line Of Sight ◽  
Emission Region ◽  
Physical Size ◽  
Line Region ◽  
Region 10

In the spectrum of the young bipolar planetary nebula M2-9, we detected the He II Raman scattered feature at 6545 Å. However, in the same spectrum the He II emission lines at 6527 Å and 6560 Å are absent, which implies that the He II emission region is hidden from our line of sight and that the H I scattering region is pretty much extended not to be obscured entirely. We perform photoionization computations to estimate the physical size of the He II emission line region ≲ 1015 cm in the presence of hot luminous star with T ≳ 105 K and L ≲ 103L⊙.

scholarly journals V1016 Cygni, Spectral Observations 1968—1971

1971 ◽  
Vol 15 ◽  
pp. 73-84 ◽  
Author(s):  
M. Pim Fitzgerald
Keyword(s):  
Radial Velocity ◽  
Planetary Nebula ◽  
Emission Lines ◽  
Relative Lack ◽  
Line Intensities ◽  
Line Widths ◽  
Increased Strength ◽  
Detailed Picture ◽  
Balmer Decrement ◽  
The Continuum

AbstractIdentification of approximately 230 emission lines between 3120 Å and 5045 Å have been made on twelve plates taken between 1968 and 1971. The line intensities and ratios fail to give a consistent detailed picture of the nebula, but indicate that on average the electron pressure and density have changed little. The Balmer decrement has become less steep since 1968, indicating higher optical depth. However, the permitted iron lines have completely gone, indicating lower density. Excitation is increasing in some parts of the nebula, as indicated by the increased strength of the [Fe V] lines, and the recent appearance of strong lines of [Ne Y]. The continuum remains weak, though it is easily seen on plates taken on April 8, 1969, and on those taken in June 1971. The radial velocity of the object fluctuates between —50 and — 70 km/sec, and the line widths remain about 120 km/sec. The wing to the violet of the emission lines is still present. The continued brightness of this object, and the relative lack of change in the spectrum over several years, indicate even more strongly that V 1016 Cygni is likely to be a planetary nebula in the stages of formation.

scholarly journals Fading and variations in the spectrum of the central star of the young Planetary Nebula SAO 244567 (Hen 1357)

1997 ◽  
Vol 180 ◽  
pp. 123-124
Author(s):  
M. Parthasarathy ◽  
P. Garcia-Lario ◽  
D. de Martino ◽  
S. R. Pottasch ◽  
S.F. de Cordoba
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Optical Spectrum ◽  
Central Star ◽  
Alpha Emission

SAO 244567 (= Hen 1357) is a very young planetary nebula. It was discovered by Parthasarathy et al. (1993, A and A 267, L19). Based on the spectrum obtained around 1950 Henize (1976, ApJ Suppl 30, 491) classified it as a B or A type H-alpha emission line star. The optical spectrum of SAO 244567 obtained in 1971 shows that it was a post-AGB B1 supergiant at that time. It has turned into a planetary nebula within the last 20 years (Parthasarathy et al. 1995, A and A 300, L25).

Cation exchange assisted synthesis of ZnCdSe/ZnSe quantum dots with narrow emission line widths and near-unity photoluminescence quantum yields

2020 ◽  
Vol 56 (45) ◽  
pp. 6130-6133 ◽  
Author(s):  
Xiao Jin ◽  
Kanlin Xie ◽  
Tingting Zhang ◽  
Huada Lian ◽  
Zhenghe Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Emission Line ◽  
Cation Exchange ◽  
Quantum Yields ◽  
Line Widths ◽  
Narrow Emission

ZnCdSe/ZnSe quantum dots reveal a notable FWHM of 17.1 nm with a near-unity PL QY at 631 nm.

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