scholarly journals A Flare on AD Leo observed in Optical, UV and Microwaves

1989 ◽  
Vol 104 (2) ◽  
pp. 63-66
Author(s):  
P.B. Byrne ◽  
D.E. Gary
Keyword(s):  
Emission Line ◽  
Transition Region ◽  
Photometric Observation ◽  
The Other ◽  
Optical Flare

SummaryWe report a simultaneous IUE, VLA and ground-based photometric observation of a flare on the dMe star, AD Leo, on 2nd February 1903. The optical flare was extremely impulsive, lasting in total only about 3 mins. A relatively longlived 6 cm flare was observed with the VLA which was initially 100% polarized. An IUE spectrum, taken ≈ 8 min after the onset of the optical U band flare, shows motu than a factor of 2 increase in the Ha II λ 1640Å emission line. The other mid-transition region lines such as C IV λλ154B/52Å show almost no response.

scholarly journals CO and OH in the Galactic Center Region

1980 ◽  
Vol 87 ◽  
pp. 111-112
Author(s):  
Junji Inatani ◽  
Nobuharu Ukita
Keyword(s):  
Emission Line ◽  
Intensity Ratio ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Point Of View ◽  
The Other ◽  
Kinetic Temperature ◽  
Two Dimensional ◽  
Center Region ◽  
Dimensional Distribution

The two-dimensional distribution of molecular clouds in the galactic center region has been investigated in the CO 115 GHz line and in the OH 1665 and 1667 MHz lines. As the former is an emission line, we can find molecular clouds without the unavoidable bias to continuum sources which is inherent in a survey of OH absorption lines. Because the CO line is usually optically thick, the brightness temperature of the line is directly related to the kinetic temperature of the cloud. On the other hand, the real optical depth of the OH line can be obtained from the intensity ratio between 1665 and 1667 MHz lines (assuming LTE). From this point of view we have compared the CO and OH observational results.

scholarly journals The Nature and Origin of Structure in Broad Emission Line Profiles

1997 ◽  
Vol 159 ◽  
pp. 193-194 ◽  
Author(s):  
C. Martin Gaskell ◽  
Stephanie A. Snedden
Keyword(s):  
Emission Line ◽  
The Other ◽  
Central Component ◽  
Balmer Line ◽  
Line Profiles ◽  
Broad Emission ◽  
Broad Emission Line

AbstractWe postulate that all structure in broad lines can be explained by a central component (at the systemic redshift) and the addition of two ‘displaced components’, one blueshifted and the other redshifted. We have been able to successfully classify all Balmer-line profiles on this basis. 3C 390.3-type objects are merely examples where the shifts of the displaced components are unusually large. We believe that the displaced peaks are less prominent in the UV lines because the higher ionization lines are broader.

Arp 70: an interacting galaxy with extreme outflows

2020 ◽  
Vol 493 (1) ◽  
pp. 1434-1446
Author(s):  
A Camps-Fariña ◽  
J E Beckman ◽  
J Font ◽  
I del Moral-Castro ◽  
S F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
The Other ◽  
Spectral Signature ◽  
Main Peak ◽  
Physical Parameters ◽  
Line Profiles ◽  
Public Repository ◽  
Line Region ◽  
Fabry Perot ◽  
H Ii Region

ABSTRACT We analysed a Fabry–Pérot (FP) cube of the interacting pair of galaxies Arp 70, which was obtained from the CeSAM public repository of FP data. On the larger galaxy Arp 70b, we detected the spectral signature of two different outflows, one located in the centre and the other associated with a giant H ii region in the arm region. The central outflow is especially prominent, with the flux of the secondary peaks in the emission-line profiles due to the outflowing gas being similar to that of the main peak. We used an archive fibre spectrum from SDSS to confirm this detection in H α as well as in the [N ii] line and, in addition, to perform diagnostics on the nature of the ionization. The emission at the centre is consistent with a low-ionization nuclear emission-line region and a weak active galactic nucleus. Using the spatial distribution of the profiles in the FP cube, we estimated the shape of the outflow which is consistent with two cones of expanding material, one approaching and the other receding from us, and used this to estimate the physical parameters of the outflow, finding energies of order 1057 erg and masses of order 108 M⊙. On the giant H ii region, we found a very large expanding superbubble with a diameter of ∼5 kpc. The bubble has an energy of order 1054 erg and a mass of about 4 × 107 M⊙. We discuss the possible origins for both of these features and whether they could be associated with the interaction between the galaxies.

scholarly journals Isotope shift in the resonance line of magnesium

1936 ◽  
Vol 154 (883) ◽  
pp. 679-683 ◽  
Keyword(s):  
Emission Line ◽  
Hyperfine Structure ◽  
Atomic Beam ◽  
Resonance Line ◽  
Isotope Shift ◽  
Wave Length ◽  
Spectral Lines ◽  
The Other ◽  
Absorption Lines ◽  
Doppler Width

By making use of an atomic beam instead of an ordinary gas or vapour, it is possible to observe structures of spectral lines very much smaller than the normal Doppler width. The structure of resonance lines can thus be observed as fine absorption lines on the background of the emission line possessing the full Doppler width. This method was used by the present authors for the detection and measurement of the hyperfine structure of the resonance lines of potassium and sodium. The following paper gives an account of the investigation of the structure of the singlet resonance line (2852 A) of magnesium by the same method. The line was found to possess two components at a separation of 0.033 cm -1 , the component of longer wave-length being very much stronger than the other.

scholarly journals Kinematics and dynamics of galactic Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 407-407
Author(s):  
S. Durand
Keyword(s):  
Emission Line ◽  
Milky Way ◽  
Large Range ◽  
Planetary Nebulae ◽  
The Other ◽  
Initial Mass ◽  
Kinematics And Dynamics ◽  
Astrophysical Interest ◽  
Bright Emission ◽  
Bright Emission Line

Planetary Nebulae (PNe) are transient objects of considerable astrophysical interest: there are thought to descend from low and intermediate initial mass stars and therefore cover a large range of ages. On the other hand there are easily identified thanks to their bright emission-line spectra. In view of this it is perhaps surprising that little use has been made of PNe for kinematical studies of the Milky Way.

scholarly journals Far-Ultraviolet and Visible Observations of Flares on dme Stars

1983 ◽  
Vol 71 ◽  
pp. 245-248
Author(s):  
G E Bromage ◽  
B E Patchett ◽  
K J H Phillips
Keyword(s):  
Solar Flare ◽  
Transition Region ◽  
The Other ◽  
Ev Lac ◽  
Far Ultraviolet ◽  
Large Flare ◽  
Region Line ◽  
Line Strengths

ABSTRACTFour large flare events – one on each of the dMe stars UV Cet, AT Mic, EV Lac and EQ Peg – have been witnessed during a total of 17½ hours of far-UV (λλ1150-1950) IUE exposures. Some observational characteristics of these four events are compared. Two showed strong enhancements of chromospheric and transition-region line strengths. The other two did not, even though their visible flares were intense (ΔU ~ 2 mag). The brightest UV flare spectrum (EQ Peg) is contrasted with that of the largest solar flare seen from ‘Skylab’.

scholarly journals Nuclear Activity in the Hickson Compact Groups of Galaxies

1999 ◽  
Vol 186 ◽  
pp. 418-418
Author(s):  
M. Shimada ◽  
S. Nishiura ◽  
Y. Ohyama ◽  
T. Murayama ◽  
Y. Taniguchi
Keyword(s):  
Emission Line ◽  
The Other ◽  
Compact Groups ◽  
Early Type ◽  
Late Type ◽  
No Emission ◽  
Nuclear Activity ◽  
Groups Of Galaxies ◽  
Nearby Galaxies ◽  
Hickson Compact Groups

In order to study environmental effects on the nuclear activity in galaxies, we have been conducting a spectroscopic study of Hickson Compact Groups of galaxies (HCGs, Hickson 1982) which are the densest agglomeration of galaxies. We obtained nuclear spectra of 62 galaxies in 29 HCGs in the spectral range 6200–7000Å with the 188cm telescope at Okayama Astrophysical Observatory. These spectra were classified into the three types by using the emission line ratio [NII]λ6583/Hα; (1) AGN: [NII]λ6583/Hα >0.6, (2) HII nuclei: [NII]λ6583/Hα <0.6, and (3) Absorption: no emission line. We compared the nuclear activity of galaxies in HCGs with that of nearby galaxies (Ho 1996; Ho, Filippenko & Sargent 1997) which provides a representative sample of field galaxies. In early-type spirals (Sa-Sbc), the fraction of HII nuclei in HCGs is smaller than that in the field galaxies, while the fraction of absorption in HCGs is larger than that in field galaxies. On the other hand, in early-type galaxies (E-S0a) and late-type spirals (Sc-P), we found little difference in the nuclear activity between HCGs and field galaxies.

scholarly journals The photosynthesis of hydrogen chloride. II. —“Oxygen free” mixtures

1933 ◽  
Vol 140 (840) ◽  
pp. 112-125 ◽  
Keyword(s):  
Comparative Study ◽  
Transition Region ◽  
Hydrogen Chloride ◽  
The Other ◽  
Pure Hydrogen ◽  
Self Consistent ◽  
Complete Study ◽  
Chlorine Reaction ◽  
Kinetics Of ◽  
Rich Mixtures

The complete study of the photochemical hydrogen-chlorine reaction falls into four sections consequent upon the fact that the presence of oxygen in large or small quantity very materially alters the kinetics of the process. These may be classified as follows:— (1) The kinetics of pure hydrogen-chlorine mixtures. (2) The kinetics of oxygen-rich mixtures. (3) The transition region between (1) and (2). (4) The photosensitized formation of water associated with (2) and (3). A mechanism proposed for any one of the above processes must be consistent with the other three, and a full and comparative study of all four should lead to a self-consistent mechanism by which all the above aspects of the problem can be unified in one explanation.

scholarly journals A Summary of the Observations of the Twin QSOs, 0957+561 A, B

1980 ◽  
Vol 92 ◽  
pp. 181-184
Author(s):  
Frederic H. Chaffee ◽  
Ray J. Weymann ◽  
Marc Davis ◽  
Nathaniel P. Carleton ◽  
D. Walsh ◽  
...  
Keyword(s):  
Emission Line ◽  
Absorption Line ◽  
Point Sources ◽  
The Other ◽  
Gravitational Lens ◽  
Time Interval ◽  
Radio Structure ◽  
Angular Extent ◽  
Relative Brightness ◽  
Time Variations

An analysis of all observations of the “twin” QSOs, 0957+561 A, B, to date does not yet allow us to distinguish between their being two nearly identical QSOs or a single QSO split into two images by an intervening gravitational lens. The more identical the two objects are found to be, the more difficult any explanation which postulates the existence of two distinct QSOs becomes. Jodrell Bank and VLA observations reveal additional radio structure to the northeast of the northern QSO image which, if physically associated with a single QSO doubly imaged by a gravitational lens, would itself be imaged weakly to the southwest. More detailed radio mapping should be able to test the existence of such an image.The VLBI map of Porcas and his collaborators reveals that the radio images corresponding to the optical ones are point sources separated by 6.175 arcsec having an angular extent to less than 20 milliarcseconds, whereas all further radio structure is resolved out.Optical spectroscopy of the twins reveals two nearly identical sources with indistinguishable emission line redshifts and with absorption line redshifts identical to within 15 km/sec. It is the identity of these optical characteristics which makes all non-gravitational lens hypotheses most difficult.The most compelling test of the lens hypothesis is the measurement of time variations of the two images at as many wavelengths as possible. If brightness variations of one image are repeated by the other after a time interval determined by the details of the observerlens-QSO geometry (such an interval could be of the order of many months or years) the lens hypothesis would be confirmed. Several observations indicate prior variations of the images, and programs to monitor their relative brightness in the future will be of great importance.

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