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 The X-Ray Nova GRO J0422+32 in Decline and Quiescence

1996 ◽  
Vol 158 ◽  
pp. 399-400
Author(s):  
M. R. Garcia ◽  
P. J. Callanan ◽  
J. E. McClintock ◽  
P. Zhao
Keyword(s):  
Emission Line ◽  
Emission Region ◽  
Dwarf Novae ◽  
X Ray ◽  
First Order ◽  
Band Emission ◽  
Line Region ◽  
Hα Emission ◽  
The Stability ◽  
The Continuum

We have followed the X-ray nova GRO J0422+32, spectroscopically and photometrically, throughout the decline to quiescence.In the final stages of decay (days 430…880 after the outburst, see Callanan et al. (1995) for the epoch 1995), the equivalent width (EW) of the Hα emission increases monotonically and the R magnitude decreases monotonically. This suggests that the flux in the Hα line is constant, while the continuum fades. The Hα flux is the product of the R band flux (F(R), arbitrarily scaled to 100 at R = 19 mag) and the EW, and is shown in the last column of the table below. The Hα flux varies by only ~ 30% while the continuum fades by a factor of eight (from R = 19 mag to R = 21.3 mag). So, to first order, the Hα luminosity is constant in the final stages of decay. While it is generally the case that the emission line EWs in individual dwarf novae also increase during the decay, the exact behavior seen in GRO J0422+32 is not what is seen for dwarf novae (on average). Using the relation between EW[Hβ] and Mv given in figure 6 of Patterson (1984), we would expect a factor of ~ 5 variation in the Hα flux during days 430…880. The stability of the Hα flux implies that somehow the emission line region is ‘disconnected’ from the continuum (R–band) emission region.

scholarly journals Optical spectroscopy of type 2 LINERs

2020 ◽  
Vol 635 ◽  
pp. A50
Author(s):  
L. Hermosa Muñoz ◽  
S. Cazzoli ◽  
I. Márquez ◽  
J. Masegosa
Keyword(s):  
Emission Line ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
True Nature ◽  
Star Forming ◽  
Broad Component ◽  
Line Region ◽  
Line Fitting

Context. Type 2 Low-ionization Nuclear Emission-line Regions (LINERs) have been optically classified with the Palomar data as not presenting a broad component in the Balmer emission lines that are associated with the broad-line region (BLR) of the active galactic nuclei (AGN). Aims. We aim to unveil the presence of different kinematic components of emission lines in the nuclear region of a sample of local (z ≤ 0.022) type 2 LINERs. We focus on the analysis of the true nature of LINERs by means of the detection (or nondetection) of a broad component that originated in the BLR of the AGN. Additionally, we search for the possible presence of nonrotational motions such as outflows in these LINERs. Methods. We applied a decomposition of the nuclear emission lines using an spectroscopic analysis of the optical spectra of nine type 2 LINERs of intermediate-resolution spectroscopic data retrieved from the Hubble Space Telescope (HST) archive. The study is completed with archival spectra from the Double Spectrograph from the Palomar Observatory. Results. The emission line fitting reveals the presence of a broad component associated with the BLR in six out of the nine galaxies for the space-based data, and for two out of the eight from the ground-based spectra. The velocity dispersion for two galaxies (NGC 4486 and NGC 4594) measured in HST/STIS data suggest the presence of outflows. Conclusions. The results indicate that the spatial resolution plays a major role in the detection of the BLR, as it appears diluted in the ground-based data (even after removing stellar contribution). This is also true for the emission line diagnostics, as the contaminant light contributes to lower emission line ratios toward the star-forming area of standard BPTs. We propose to reclassify NGC 4594 as a type 1 LINER, since a BLR component is seen in both space- and ground-based spectra. We find ambiguous results for the BLR component of NGC 4486. The modest outflow detection in our sample may indicate that they are not as frequent as seen for type 1 LINERs.

An Extended Emission Line Region around Mrk 1172

2019 ◽  
Vol 15 (S359) ◽  
pp. 438-440
Author(s):  
Augusto Lassen ◽  
Rogério Riffel ◽  
Ana L. Chies-Santos ◽  
Evelyn Johnston ◽  
Boris Haeussler ◽  
...  
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Emission Lines ◽  
Gas Content ◽  
Early Type ◽  
Strong Emission ◽  
Line Region ◽  
Hard Radiation ◽  
Star Formation Activity ◽  
Extended Emission

AbstractWe serendipitously found an intriguing Extended Emission Line Region (EELR) near the quiescent and massive early-type Mrk 1172, with a projected extension of approximately 14 × 14 kpc. Its irregular shape, high gas content, strong emission lines and proximity to an isolated possible faded quasar raise questions about the ionization of this gas and the nature of this object. Analyzing the stellar population in both objects we observe that the EELR has a dominance of young-intermediate and intermediate stellar populations (200 Myr < t < 1 Gyr) with significant star formation activity, while Mrk 1172 is dominated by old stellar population (t > 5 Gyr). BPT diagnostic diagrams indicate that the gas in the EELR is photoionized by hot massive stars rather than by a hard radiation field or by shocks. Further analysis on abundances of the gas and its kinematics shall be performed to better comprehend the nature of this object and how it is interacting with Mrk 1172.

scholarly journals Spectral variability of the 3C 390.3 nucleus for more than 20 years – II.  Variability of the broad emission-line profiles and He ii λ4686 Å emission-line fluxes

2020 ◽  
Vol 495 (1) ◽  
pp. 971-980
Author(s):  
S G Sergeev
Keyword(s):  
Emission Line ◽  
Emission Region ◽  
Line Profiles ◽  
Broad Emission ◽  
Line Region ◽  
Balmer Lines ◽  
Optical Continuum ◽  
Broad Emission Line ◽  
Disc Configuration ◽  
Factor C

ABSTRACT Results of the analysis of the variability of the H β and H α broad emission-line profiles and the He ii λ4686 Å emission-line fluxes in the 3C 390.3 nucleus during 1992–2014 are present. The observed velocity-dependent lag for the Balmer lines is similar to that expected from the Keplerian disc configuration, although there are some differences. Probably, a radial infall motion can be present in the broad-line region of 3C 390.3 in addition to the Keplerian rotation. The lag of the broad He ii line is 26 ± 8 d, significantly less than that of the Balmer lines, so the He ii emission region is much smaller in size. In terms of the power-law relationship between line and optical continuum fluxes with slowly varying scale factor c(t): $F_{\rm line}\propto c(t)\, F_{\rm cont}^a$, the power a is 1.03 for the broad He ii line, while according to Paper I, the power is equal to 0.77 and 0.54 for the broad H β and H α lines, respectively. It means that the variability amplitude is the largest in the He ii, less in H β, and more less in H α. However, the Balmer lines contain a long-term trend that is not seen in the helium line. The narrow He ii line is variable with the amplitude (max-to-min ratio) Rmax ≈ 3, which is much greater than the variability amplitudes of both the narrow Balmer lines and the narrow [O iii] λ5007 Å line.

scholarly journals Planetary Nebulae Symposium - Introductory Remarks

1978 ◽  
Vol 76 ◽  
pp. XIX-XXI
Author(s):  
Yervant Terzian
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Emission Lines

It seems proper to start our Symposium from the very beginning. The oldest known discovery of a planetary nebula dates back to Messier who in 1764 catalogued the Dumbbell nebula, NGC 6853, as Messier 27. Only 100 years later Huggins discovered the emission line spectra of planetary nebulae and he pointed out that his discovery proves that these objects are not clusters of stars but are “enormous masses of luminous gas or vapor”. In 1887, a curious suggestion was made by Lockyer who thought that the nebulae were clusters of burning meteorites when he incorrectly identified three nebular emission lines with magnesium.

scholarly journals Evidence for disks around certain luminous Magellanic cloud stars from the study of FeII

1987 ◽  
Vol 122 ◽  
pp. 443-444
Author(s):  
G. Muratorio ◽  
M. Friedjung
Keyword(s):  
Energy Distribution ◽  
Emission Line ◽  
Line Emission ◽  
Magellanic Cloud ◽  
Emission Lines ◽  
Absorption Lines ◽  
Line Of Sight ◽  
Continuous Energy

Study of FeII emission lines in emission and absorption using both emission line self absorption curves and ultraviolet spectral synthetis, shows that line emission is produced in the case of certain luminous Magellanic Cloud stars, in a region not in front of the photosphere. This region is most easily understood as being a disk. Absorption lines of FeII are either produced by a wind, or if the disk inclination is small with respect to the line of sight, in layers associated with the disk. The presence of disks also helps one to explain the form of the continuous energy distribution.

scholarly journals Emission-Line Variability and the Nature of the Broad-Line Region

1989 ◽  
Vol 134 ◽  
pp. 97-99
Author(s):  
B. M. Peterson
Keyword(s):  
Emission Line ◽  
Strong Correlation ◽  
Emission Lines ◽  
Broad Line ◽  
Rapid Variability ◽  
Broad Line Region ◽  
Line Region

Variability of the emission-line spectra of broad-line AGNs is now a well-established phenomenon (see Peterson 1988 for a review). The rapid variability of the emission lines and the strong correlation between continuum and line fluxes suggests broad-line region (BLR) dimensions too small to be consistent with theoretical estimates based on photoionization equilibrium considerations.

scholarly journals Microlensing Induced Spectral Variability In Q2237+0305

1996 ◽  
Vol 173 ◽  
pp. 241-246
Author(s):  
Geraint F. Lewis ◽  
Mike J. Irwin ◽  
Paul C. Hewett
Keyword(s):  
Emission Line ◽  
Line Emission ◽  
Emission Lines ◽  
Broad Line ◽  
Spectral Variability ◽  
Broad Emission ◽  
Quasar Spectra ◽  
Line Region ◽  
Broad Emission Line ◽  
The Continuum

The degree of microlensing induced amplification is dependent upon the size of a source. As quasar spectra consist of the sum of emission from different regions this scale dependent amplification can produce spectral differences between the images of a macrolensed quasar. This paper presents the first direct spectroscopic evidence for this effect, providing a limit on the scale of the continuum and the broad line emission regions at the center of a source quasar (2237+0305). Lack of centroid and profile differences in the emission lines indicate that substructure in the broad emission line region is > 0.05 parsecs.

scholarly journals The Weak Emission Line Stars

2003 ◽  
Vol 209 ◽  
pp. 235-236
Author(s):  
Jeffrey Fogel ◽  
Orsola De Marco ◽  
George Jacoby
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Type I ◽  
Evolutionary Sequence ◽  
Lower Mass ◽  
Stellar Temperatures ◽  
Central Stars

In this paper, we study the evolution of the weak emission line central stars of planetary nebula (WELS), which are similar to the H-deficient Wolf-Rayet central stars except for systematically weaker emission lines. Our attempts at finding an evolutionary sequence for the WELS similar to what was established for Wolf-Rayet central stars, were unsuccessful. No correlation was found between any of the analysed quantities: emission and absorption line fluxes or stellar and nebular parameters from the literature. It does appear, however, that WELS have intermediate stellar temperatures (30–80 kK), and do not reside in the middle of Type I planetary nebulae, possibly indicating lower mass precursors.

Optical long-slit spectroscopy in the cluster Abell S0805

2019 ◽  
Vol 488 (3) ◽  
pp. 3685-3715
Author(s):  
P C da Rocha-Poppe ◽  
V A Fernandes-Martin ◽  
M Faúndez-Abans ◽  
M de Oliveira-Abans ◽  
G A Silva ◽  
...  
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Spectral Synthesis ◽  
Emission Lines ◽  
Cluster Galaxy ◽  
Nuclear Activity ◽  
Star Forming ◽  
Line Region ◽  
Nitrogen Emission ◽  
First Time

ABSTRACT This contribution aims to study the nature (kinematic, nuclear activity, and stellar population) of a sample of 10 galaxies in the poor cluster Abell S0805. As no detailed optical spectroscopy for some members has been published yet, the selected sample makes this study ideal for investigating the properties of the following objects: ESO 104- G(002, 006, 007, 008, 009, 010, 013), Fairall 0187, and PGC (062384, 062391). Our main results were obtained after subtraction of the underlying stellar population with the spectral synthesis code starlight. The residual spectra reveal seven galaxies with only absorption lines [ESO 104- G(002, 007, 008, 009), Fairall 0187 and PGC (062384, 062391)], and three galaxies with emission lines [ESO 104- G(006, 010, 013)]. According to the boundaries in the diagnostic diagrams, the intensities of H α and the low-ionization lines ([N ii] λ6584 Å and [S ii] λλ6716,6731 Å) suggest the following results: (i) the brightest cluster galaxy (ESO 104- G006, an elliptical cD galaxy) shows low-ionization nuclear emission-line region (LINER)-like excitation, quite common in ‘cool core clusters’; (ii) the ESO 104- G010 (‘X-Galaxy’ or ‘Crystal Frog’) shows an excess of the nitrogen emission-line [N ii] λ6584 Å not yet reported. We also suggest this object as a LINER; (iii) the spiral ESO 104- G013 is a star-forming galaxy with typical emission lines. No obvious signs of interaction were observed in this study. The heliocentric velocities agree within 1σ with the most recent values. The stellar population, rotation curves, and velocity dispersions are also discussed for the first time for some objects.

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