scholarly journals Near-IR spectroscopic monitoring of WR 140 (WC7pd+O4-5) during the 2001 periastron passage

2003 ◽  
Vol 212 ◽  
pp. 253-254
Author(s):  
Watson P. Varricatt ◽  
Peredur M. Williams ◽  
Nagarhalli M. Ashok
Keyword(s):  
Emission Line ◽  
Ir Spectrum ◽  
Emission Lines ◽  
X Ray ◽  
Spectroscopic Monitoring ◽  
Near Ir ◽  
Wind Activity ◽  
Ir Spectroscopic ◽  
Emission Line Profile ◽  
The Continuum

The near-IR spectrum of the periodic dust making WCpd+O4-5 binary WR 140 was monitored to cover the 2001 periastron passage and maximum colliding-wind activity. The He i λ1.083μm emission-line profile showed the appearence of a subpeak on epochs close to periastron passage. The evolution of the subpeak was consistent with the motion of the stars and the colliding wind region. The appearance and evolution of the emission subpeak suggests that the theoretical 1/r dependence of X-ray flux does not hold, so that there is no need to change the values of eccentricity and epoch of periastron passage derived from the RV orbit. JHK spectra show variations of the continuum and and dilution of the emission lines, in agreement with the production and cooling of dust.

scholarly journals Broad He i 1.08-µm absorption from the obscurer in the active galaxy NGC 5548

2020 ◽  
Vol 500 (2) ◽  
pp. 2063-2075
Author(s):  
Conor Wildy ◽  
Hermine Landt ◽  
Martin J Ward ◽  
Bożena Czerny ◽  
Daniel Kynoch
Keyword(s):  
Active Galaxy ◽  
Time Variability ◽  
Broad Absorption ◽  
X Ray ◽  
Spectroscopic Monitoring ◽  
Near Ir ◽  
Ngc 5548 ◽  
Ir Spectroscopic ◽  
Ionization Parameter ◽  
High Column

ABSTRACT The nucleus of the active galaxy NGC 5548 was the target of two intensive spectroscopic monitoring campaigns at X-ray, ultraviolet (UV), and optical frequencies in 2013/2014. These campaigns detected the presence of a massive obscuration event. In 2016/2017, Landt et al. conducted a near-IR spectroscopic monitoring campaign on NGC 5548 and discovered He i  1.08-μm absorption. Here, we decompose this absorption into its components and study its time variability. We attribute the narrow He  i absorption lines to the warm absorber (WA) and, as for the newly appeared low-ionization WA lines in the UV, their presence is most likely due to a reduction in ionization parameter caused by the obscurer. The observed variability of the narrow He i absorption is consistent with what is expected for the WA. Most importantly, we also detect fast, broad He i absorption, which we attribute to the obscurer. This He i broad absorption, which is indicative of a high column density gas, is unsaturated and variable on time-scales of a few months. The observed variability of the obscurer is mainly due to changes in ionization, although density changes also play a role. We test the physical cycle model of Dehghanian et al. which proposes that helium recombination can account for how the obscurer influences the physics of the WA gas. Our results support their model, but also indicate that the reality might be more complex.

scholarly journals H2 Emission from External Galaxies

1992 ◽  
Vol 150 ◽  
pp. 103-107
Author(s):  
Kimiaki Kawara
Keyword(s):  
Uv Radiation ◽  
Supernova Remnants ◽  
Emission Lines ◽  
Hot Stars ◽  
Shock Excitation ◽  
X Ray ◽  
Spectroscopic Observations ◽  
Near Ir ◽  
Bare Nucleus ◽  
External Galaxies

2 μm spectroscopic observations by many authors have revealed significant rotation-vibrational H2 emission is widespread from starburst to bare nucleus galaxies. Near-IR H2 emission lines can arise from various excitation sources: UV radiation by hot stars, shock excitation by supernova remnants or AGN driven winds, and UV/X-ray radiation by an AGN. In this review recent data will be compared with such H2 excitation models.

scholarly journals Evolution and State of the Local ISM

1996 ◽  
Vol 171 ◽  
pp. 442-442
Author(s):  
T. Schmutzler ◽  
D. Breitschwerdt
Keyword(s):  
Basic Feature ◽  
Emission Lines ◽  
Continuum Emission ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Self Consistent ◽  
X Ray Background ◽  
Collisional Ionization ◽  
Consistent Approach ◽  
The Continuum

The most puzzling observations concerning the LISM (distance < 100 pc) can be explained by a fast adiabatically cooled gas in the cavity of an old superbubble. The ultrasoft X-ray background and contributions to the C- and M-bands are due to the continuum emission of delayed recombination [1]. In contrast to collisional ionization equilibrium (CIE) models, but consistent with recent observations [2], our model predicts a lack of emission lines and a low emissivity in the EUV range. In the figure below we compare the emissivities resulting from CIE at T = 106 K and those from our model at T = 4.2 × 104 K. The basic feature of our model is a thermally self-consistent approach of the time-dependent evolution.

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 Slow decline and rise of the broad [O iii] emission line in globular cluster black hole candidate RZ2109

2019 ◽  
Vol 489 (4) ◽  
pp. 4783-4790 ◽  
Author(s):  
Kristen C Dage ◽  
Stephen E Zepf ◽  
Arash Bahramian ◽  
Jay Strader ◽  
Thomas J Maccarone ◽  
...  
Keyword(s):  
Black Hole ◽  
Emission Line ◽  
Globular Clusters ◽  
X Ray ◽  
Hydrogen Emission ◽  
Black Hole Candidate ◽  
The Core ◽  
Spectroscopic Monitoring ◽  
Slow Decline ◽  
Over Time

ABSTRACT RZ2109 is the first of several extragalactic globular clusters shown to host an ultraluminous X-ray source. RZ2109 is particularly notable because optical spectroscopy shows it has broad, luminous [O iii] λλ4959,5007 emission, while also having no detectable hydrogen emission. The X-ray and optical characteristics of the source in RZ2109 make it a good candidate for being a stellar mass black hole accreting from a white dwarf donor (i.e. an ultracompact black hole X-ray binary). In this paper we present optical spectroscopic monitoring of the [O iii]5007 emission line from 2007 to 2018. We find that the flux of the emission line is significantly lower in recent observations from 2016 to 2018 than it was in earlier observations in 2007–2011. We also explore the behaviour of the emission line shape over time. Both the core and the wings of the emission line decline over time, with some evidence that the core declines more rapidly than the wings. However, the most recent observations (in 2019) unexpectedly show the emission line core rebrightening

scholarly journals X-ray Spectroscopy of the Ultra-soft Transient 4U1543-47

1990 ◽  
Vol 115 ◽  
pp. 205-208
Author(s):  
H. van der Woerd ◽  
N.E. White ◽  
S.M. Kahn
Keyword(s):  
Emission Line ◽  
Compact Object ◽  
Relativistic Effects ◽  
Emission Feature ◽  
Continuum Emission ◽  
X Ray ◽  
Black Hole Candidate ◽  
Transmission Grating ◽  
Cool Plasma ◽  
The Continuum

AbstractThe X-ray transient 4U1543-47 was observed in 1983 by the EXOSAT observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). Two emission line features are resolved. A broad (FWHM ~2.7 keV) line at 5.9 keV is detected in the GSPC, which we interprete as a redshifted and broadened iron Kα line. The Une broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth (τ ≈ 5), or from Doppler and relativistic effects in the vicinity of a compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission line feature at 0.74 keV, which may be an iron L-transition complex. However, we find that such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral Oxygen. The continuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from a very cool plasma (kT = 0.84 keV) with large scattering depth (τ ≈ 27). The continuum spectrum is strikingly similar to that of black hole candidate LMC X-3.

scholarly journals Near-IR Spectroscopic Monitoring of Jupiter at the Time of the SL-9 Impact

1995 ◽  
Vol 10 ◽  
pp. 629-630 ◽  
Author(s):  
R. Schulz ◽  
Th. Encrenaz ◽  
J.A. Stüwe ◽  
G. Wiedemann
Keyword(s):  
Spectroscopic Monitoring ◽  
Near Ir ◽  
Ir Spectroscopic

scholarly journals A stellar census in globular clusters with MUSE: A spectral catalogue of emission-line sources

2019 ◽  
Vol 631 ◽  
pp. A118 ◽  
Author(s):  
Fabian Göttgens ◽  
Tim-Oliver Husser ◽  
Sebastian Kamann ◽  
Stefan Dreizler ◽  
Benjamin Giesers ◽  
...  
Keyword(s):  
Emission Line ◽  
Binary Stars ◽  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Variable Stars ◽  
Emission Lines ◽  
Data Set ◽  
Stellar Spectra ◽  
X Ray ◽  
Emission Line Galaxies

Aims. Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousand other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra (i.e. spectra that contain emission lines), we can use this large spectroscopic data set of over a million stellar spectra as a blind survey to detect stellar exotica in globular clusters. Methods. To detect emission lines in each spectrum, we modelled the expected shape of an emission line as a Gaussian curve. This template was used for matched filtering on the differences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of Hα emission are checked visually and cross-matched with published catalogues. Results. We find 156 stars with Hα emission, including several known cataclysmic variables (CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the optical counterpart of a known black hole, several probable sub-subgiants and red stragglers, and 21 background emission-line galaxies. We find possible optical counterparts to 39 X-ray sources, as we detected Hα emission in several spectra of stars that are close to known positions of Chandra X-ray sources. This spectral catalogue can be used to supplement existing or future X-ray or radio observations with spectra of potential optical counterparts to classify the sources.

scholarly journals The Timescales of Variations in Continuum and Hydrogen Lines During Stellar Flares

1983 ◽  
Vol 71 ◽  
pp. 239-243
Author(s):  
B.R. Pettersen
Keyword(s):  
Emission Line ◽  
Narrow Band ◽  
Light Curves ◽  
Emission Lines ◽  
Continuum Radiation ◽  
Stellar Flares ◽  
Hydrogen Lines ◽  
The Continuum

AbstractLight curves of major stellar flares have been used to study the behavior of U-B, B-V, and V-R. The majority of the flux transmitted through these filters is continuum radiation, but U and B are affected by emission lines. The variability of Ha and H$ emission lines were monitored through narrow band filters. The timescales of emission line variability are considerably longer than those for the continuum, and the emission line flare peak occurs a few minutes after the continuum flare maximum. No variability in lines at a timescale of seconds is detected in our data.

Electronic Structure of Al-Li Alloys by Means of Electron Microprobe

1987 ◽  
Vol 42 (12) ◽  
pp. 1385-1390 ◽  
Author(s):  
W. Franz ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Heat Treatment ◽  
Electronic Structure ◽  
Charge Transfer ◽  
Elastic Modulus ◽  
Emission Line ◽  
Electron Microprobe ◽  
Emission Lines ◽  
X Ray

By means of an electron microprobe the lithium-K-and aluminium-K-X-ray emission lines of Al-Li alloys were studied. The Li-line can be well described by the calculated emission line. The evaluation yields the transfer of electrons from the Li-s- to the Al-p-band during alloying. The charge transfer is enhanced by heat treatment. The dependence of the elastic modulus on the charge transfer is discussed.

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