scholarly journals The Radial Velocities of Planetary Nebulae in NGC 3379

1993 ◽  
Vol 155 ◽  
pp. 570-570
Author(s):  
Robin Ciardullo ◽  
George Jacoby
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Surface Photometry ◽  
Stellar Kinematics ◽  
Velocity Measurements

Several authors have analyzed the kinematics of elliptical galaxies using surface photometry in combination with absorption line velocity dispersion measurements. However, these analyses never explore the halos of galaxies, since the best absorption line measurements extend only ∼1 re. The only way to extend our knowledge of stellar kinematics to larger radii is to use the emission lines of planetary nebula for radial velocity measurements.

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.

scholarly journals The Observations of AG PEG During 1985–87

1988 ◽  
Vol 103 ◽  
pp. 257-257
Author(s):  
A.A. Boyarchuk ◽  
T.S. Belyakina ◽  
A.E. Tarasov ◽  
N. Tomov
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Radial Velocities ◽  
Light Curves ◽  
Emission Lines

AbstractThe light curves in UBVRI and profiles of the emission lines of Hα, HeII 5411 and HeI 5876, 6678 obtained during 1985–87. The radial velocities of the emission lines HeI 6678 and HeII 5411 demonstrated clear periodic variations in antiphase with the radial velocity defined for the absorption line.

scholarly journals Velocity Dispersion and Luminosity Function of Planetary Nebulae in the Nuclear Bulge of M31

1983 ◽  
Vol 103 ◽  
pp. 543-543
Author(s):  
D. G. Lawrie ◽  
H. C. Ford
Keyword(s):  
Maximum Likelihood ◽  
Radial Velocity ◽  
Luminosity Function ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Image Intensifier ◽  
Interference Filter ◽  
Radial Velocities ◽  
Method Of Maximum Likelihood ◽  
Heliocentric Velocity

We used a sequence of velocity-modulated photographs to find and measure the radial velocities of faint planetary nebulae in the center of M31. The photographs were made with a Velocity Modulating Camera (VMC) which consists of a temperature-tuned 2.1 Å (FWHM) (O III) λ 5007 interference filter, a cooled, two-stage image intensifier, and a calibrating photomultiplier. The camera was mounted at the Cassegrain focus of the Shane 3 m telescope at Lick Observatory. We identified 19 new planetary nebulae, bringing the total number of known planetaries within 250 pc of M31's nucleus to 45. From the plate series, we derived radial velocities and relative brightnesses from 32 of the nebulae and placed radial velocity limits on the remaining nebulae in the field. By applying the method of maximum likelihood to the observed radial velocity distribution, we derive a mean heliocentric velocity of −309 (±25) km s−1 and a velocity dispersion of 155 (±22) km s−1 for the planetary nebulae.

scholarly journals Spectroscopy of Extragalactic Planetary Nebulae in the Ultraviolet

1983 ◽  
Vol 103 ◽  
pp. 545-545
Author(s):  
T.R. Gull ◽  
S.P. Maran ◽  
T.P. Stecher ◽  
L. H. Aller
Keyword(s):  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
High Excitation ◽  
Long Wavelength ◽  
International Ultraviolet Explorer ◽  
Interstellar Media ◽  
Progenitor Stars ◽  
Stellar Envelopes

Three high-excitation planetary nebulae in the Magellanic Clouds were successfully observed with the International Ultraviolet Explorer. Emission lines as well as nebular and stellar continua were detected. Fluxes in the lines 1550 C IV, 1640 He II, 1663 O III, and 1909 C III were measured in spectra of LMC P40, SMC N2, and SMC N5 obtained with the IUE short wavelength spectrograph; 2422 Ne IV was measured in P40 with the long wavelength spectrograph. The data were analyzed together with groundbased observations by Aller in order to derive ionization models and the nebular abundances of He, C, N, O, S, Ar. The C abundances are as large as those typically found in galactic planetaries, although the interstellar media of the Clouds are notably deficient in C. Thus, the C was synthesized in the progenitor stars and presumably was lifted to the stellar envelopes by convection prior to the ejection of the nebulae. Other planetary nebulae in the Clouds, as well as the planetary nebula in the Fornax galaxy, may be observable with IUE.

scholarly journals The LAMOST spectroscopic survey of planetary nebulae in M31 and M33

2016 ◽  
Vol 12 (S323) ◽  
pp. 388-389
Author(s):  
Maosheng Xiang ◽  
Xiaowei Liu ◽  
Meng Zhang ◽  
Haibo Yuan ◽  
Zhiying Huo
Keyword(s):  
Radial Velocity ◽  
Planetary Nebulae ◽  
Radial Velocities ◽  
Velocity Measurements ◽  
The Galaxy ◽  
Galaxy Center ◽  
Projected Distance

AbstractWe present LAMOST observations and radial velocity measurements of about 1500 planetary nebulae (PNe) in M31 and M33. Most of the PNe are previously known, but 36 of them are newly discovered in the outskirts of M31, and the furthest one has a projected distance larger than 50 kpc away from the galaxy center. Eighteen objects in the area of M33 are probably newly discovered PNe, and quite a few of them are associated with previously known clusters. For all the 1500 PNe, homogeneous radial velocities are measured from the LAMOST spectra, with a typical uncertainty of a few km s−1.

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 Planetary Nebulae in the Andromeda Galaxy and its Companions

1978 ◽  
Vol 76 ◽  
pp. 19-34 ◽  
Author(s):  
Holland C. Ford
Keyword(s):  
Radial Velocity ◽  
Globular Clusters ◽  
Direct Determination ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Direct Measure ◽  
Chemical Abundances ◽  
Andromeda Galaxy ◽  
Powerful Means

The identification and observation of planetary nebulae in the Andromeda galaxy (M31) and its companions provide a powerful means of studying their old stellar populations. The direct determination of chemical abundances and radial velocities for even the brightest individual old stars is impossible at the distance of M31. The strongest emission lines of planetary nebulae are as bright as the entire visual continuum of the most luminous giants. Consequently, spectrophotometry of planetary nebulae presently provides the only direct measure of chemical abundances, and, with the exception of globular clusters, the only radial velocity determinations for the old populations.

scholarly journals Stellar Kinematics of Elliptical Galaxies in Pairs

1990 ◽  
Vol 124 ◽  
pp. 33-36
Author(s):  
Rainer Madejsky ◽  
Ralf Bender
Keyword(s):  
Radial Velocity ◽  
Elliptical Galaxy ◽  
Orbital Plane ◽  
Elliptical Galaxies ◽  
Line Of Sight ◽  
Stellar Kinematics ◽  
Velocity Difference ◽  
The Moment ◽  
Inner Parts ◽  
Very High

Observations of elliptical galaxy pairs allow the study of different states of tidal interaction between galaxies. The comparison with normal elliptical galaxies directly reveals the disturbed morphological and kinematical properties. Numerical simulations have shown that with the known initial luminosity profile, the time elapsed since closest approach between two galaxies can be estimated from the radial position of the disturbances (Aguilar and White, 1986).The two galaxy pairs Arp 166 (NGC 750/1) and 3C 278 (NGC 4782/3) considered here exhibit distorted and nonconcentric isophotes (cf. Madejsky, 1989). In Arp 166 the major relative shift of the centers of the isophotes occurs in the outer parts while in 3C 278 the nonconcentric isophotes are more pronounced in the inner parts of the galaxies, suggesting that more time ha&elapsed since the moment of closest approach in Arp 166 than in 3C 278. Furthermore, in Arp 166, both galaxies have the same radial velocity, implying that their orbital plane is perpendicular to the line of sight. In turn, the galaxies NGC 4782 and NGC 4783 are moving with a very high radial velocity difference of 680kms-1. Taking into account the location of both galaxies, which are the dominant members of a small group of about 25 galaxies (De Souza and Quintana, 1990), the true velocity difference probably is not much higher than the observed radial velocity difference. Therefore it is very likely that we are viewing at high inclination onto (i.e. nearly parallel to) the orbital plane of the galaxies NGC 4782 and 4783.

scholarly journals Neon, sulphur, and argon abundances of planetary nebulae in the sub-solar metallicity Galactic anti-centre

2018 ◽  
Vol 615 ◽  
pp. A29 ◽  
Author(s):  
G. J. S. Pagomenos ◽  
J. Bernard-Salas ◽  
S. R. Pottasch
Keyword(s):  
Planetary Nebula ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Ionic Species ◽  
Infrared Emission ◽  
Emission Lines ◽  
Solar Neighbourhood ◽  
Radial Dependence ◽  
Galactic Centre ◽  
H Ii Regions

Context. Spectra of planetary nebulae show numerous fine structure emission lines from ionic species, enabling us to study the overall abundances of the nebular material that is ejected into the interstellar medium. The abundances derived from planetary nebula emission show the presence of a metallicity gradient within the disk of the Milky Way up to Galactocentric distances of ~10 kpc, which are consistent with findings from studies of different types of sources, including H II regions and young B-type stars. The radial dependence of these abundances further from the Galactic centre is in dispute. Aims. We aim to derive the abundances of neon, sulphur and argon from a sample of planetary nebulae towards the Galactic anti-centre, which represent the abundances of the clouds from which they were formed, as they remain unchanged throughout the course of stellar evolution. We then aim to compare these values with similarly analysed data from elsewhere in the Milky Way in order to observe whether the abundance gradient continues in the outskirts of our Galaxy. Methods. We have observed 23 planetary nebulae at Galactocentric distances of 8–21 kpc with Spitzer IRS. The abundances were calculated from infrared emission lines, for which we observed the main ionisation states of neon, sulphur, and argon, which are little affected by extinction and uncertainties in temperature measurements or fluctuations within the planetary nebula. We have complemented these observations with others from optical studies in the literature, in order to reduce or avoid the need for ionisation correction factors in abundance calculations. Results. The overall abundances of our sample of planetary nebulae in the Galactic anti-centre are lower than those in the solar neighbourhood. The abundances of neon, sulphur, and argon from these stars are consistent with a metallicity gradient from the solar neighbourhood up to Galactocentric distances of ~20 kpc, albeit with varying degrees of dispersion within the data.

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.

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