scholarly journals Spectral and UBV Data for 583 Stars (Supergiants and Foreground Stars) in the Direction of the Large Magellanic Cloud

1973 ◽  
Vol 50 ◽  
pp. 293-294
Author(s):  
A. Ardeberg ◽  
J. P. Brunet ◽  
E. Maurice ◽  
L. Prévot
Keyword(s):  
Spectral Type ◽  
High Velocity ◽  
Internal Standard ◽  
Large Magellanic Cloud ◽  
Radial Velocities ◽  
Continuous Series ◽  
H Ii Regions ◽  
Single Observation ◽  
Objective Prism ◽  
Luminous Objects

The stars observed are mainly from the Catalogue by Fehrenbach and Duflot. Some other stars – overexposed on the objective-prism plates, faint blue stars in H ii regions, stars with overlapping objective-prism spectra – have been added.The photoelectric UBV photometry was done with the 1-m telescope at La Silla. The UBV filters have always been those recommended by Johnson. Normally 3 measurements or more on different nights have been made for each star. For a single observation of a program star the internal standard deviations are The spectra have been taken with a Cassegrain spectrograph mounted on the 1.52-m telescope at La Silla. The dispersion is 73 Å mm−1, the spectral range 3250-5000 Å, and the limiting resolution 1.3 Å.As a result of our observations, we present 409 stars as members of the LMC, 42 as possible members and 132 as galactic foreground stars (19 of these having high radial velocity). Remarkable features regarding velocities, spectra, magnitudes and colors are noted and commented.All stars down to B = 11.5 have been observed spectrographically as well as photometrically. This is also the case for the majority of the high-velocity stars down to B = 12.0. For fainter objects the photometry is quite representative, whereas the spectroscopy is more scarce. The limiting magnitude is B = 14.0.As radial velocities were used as membership criterion, our data do not suffer from any spectral type selection effects.It was easy to apply the MK criteria to our dispersion using the Yerkes atlas and the Bidelman list of supergiants. A continuous series of supergiant standards in the LMC has been established from 06 to G2. Comparison with Radcliffe data and with recent results of Divan gives a dispersion in spectral type of less than one tenth of a spectral class. Also the luminosity classification shows good agreement.In the classification several difficulties were met:(1) The LMC stars are very luminous objects. In the Galaxy we do not have many corresponding stars. This is especially so for later spectral types.(2) With the dispersion used, the differences between IaO and la are not very pronounced, especially not for F-G type stars.(3) Many of the LMC supergiants are P Cygni stars. They show very sharp, often asymmetric line profiles with a sharp rise to the long wavelength side. This might cause erroneous classification, and also affect radial velocities.(4) The presence of an extended atmosphere, causing dilution effects, can give spurious spectral classification.We have found 8 A type high-velocity stars. The UBV results confirm their classification. 11 G-K type stars have been found to be high-velocity stars, among which are two subdwarfs earlier discussed by Fehrenbach and Thackeray. The number of late type high-velocity stars is quite high.Full accounts have been given in Astron. Astrophys. Suppl.6 (1972), 249.

A Critical Examination of the Stock Velocity Survey

1984 ◽  
Vol 88 ◽  
pp. 231-239
Author(s):  
Wayne Osborn ◽  
D.J. MacConnell
Keyword(s):  
Recent Work ◽  
Large Scale ◽  
Practical Problem ◽  
Large Magellanic Cloud ◽  
Radial Velocities ◽  
Critical Examination ◽  
Cluster Membership ◽  
Large Numbers ◽  
Observational Technique ◽  
Objective Prism

The possibility of determining stellar radial velocities for large numbers of stars from objective-prism plates was recognized soon after objective-prism spectroscopy became a common observational technique ; (Pickering, 1887). However, the initial investigations quickly revealed a serious practical problem: how does one determine the rest wavelength position in slitless spectra? This difficulty caused the objective-prism method of obtaining radial velocities to be neglected for many years. It was not until the second half of this century that the method saw a large-scale application. This was the work of Fehrenbach who developed a technique based on a specially designed zero-deviation prism, and successfully used it to isolate members of the Large Magellanic Cloud from foreground field stars (Fehrenbach 1947a, 1947b, 1948; Fehrenbach and Duflot 1970). The Fehrenbach technique has since been applied in a number of other studies; one can mention, as examples, recent work on spectroscopie binaries (Gieseking and Karimie 1982), on cluster membership (Gieseking 1980), and on velocity dispersions at intermediate galactic latitudes (Fehrenbach and Burnage 1982).

A Search for High Velocity Stars

1984 ◽  
Vol 88 ◽  
pp. 183-186
Author(s):  
A. Florsch
Keyword(s):  
High Velocity ◽  
Galactic Plane ◽  
Photographic Plate ◽  
Radial Velocities ◽  
Density Limit ◽  
Measuring Devices ◽  
New Process ◽  
Objective Prism ◽  
Visual Measurements

Fehrenbach’s objective-prism technique for the measurement of radial velocities is well known and has already proved its efficiency. New measuring devices (MESUCOR, FENTOMIX at the O.H.P.) based on the correlation between records make the measurement more rapid and more accurate and will encourage others to use this method. An example is the Hipparcos radial-velocities program. But it is also true that this new process has its limits and does not permit one to get all the information which is on an objective-prism plate, for it is limited by the quality (principally the density) of the images. It will be necessary to continue with the classical visual measurements, especially if one wants to detect faint high-velocity stars quickly, which are often at the density limit of the photographic plate. We must keep in mind that the objective-prism technique is best for this purpose since a three or four hour exposure leads to a great number of spectra (about 60 near the pole, to 200 in the galactic plane in a field of 2X2 degrees).

scholarly journals The Southern Objective Prism Survey

1973 ◽  
Vol 50 ◽  
pp. 289-289
Author(s):  
J. Stock ◽  
H. Wroblewski
Keyword(s):  
High Velocity ◽  
Galactic Halo ◽  
Radial Velocities ◽  
Galactic Latitude ◽  
Early Type ◽  
Late Type ◽  
High Luminosity ◽  
High Galactic Latitude ◽  
Objective Prism ◽  
Halo Population

Five thousand sq deg of the Southern sky of intermediate to high galactic latitude have been surveyed with deep objective prism plates, taken with a UV-transparent prism. The plates reach on the average the 13th photographic magnitude and have been searched for the following types of objects: (1) high luminosity stars, (2) planetary nebulae, (3) metal weak late-type giants, (4) Me stars, (5) carbon stars, (6) early-type subdwarfs, (7) peculiar objects. Catalogues containing a total of over 3200 objects of these types have been compiled and will soon be published in Publ. Dpto. Astron. Univ. de Chile.Of particular interest are the metal-weak late-type giants, which are believed to be members of the galactic halo population. Slit spectra were obtained for a number of these stars and radial velocities derived. In each case the object was found to be a high velocity star. In view of the large number of such objects found in the survey, a method of determining relative radial velocities from pairs of objective prism plates was developed. The method, which is described in detail in the following paper, was tested successfully on several plate pairs, confirming the high velocities for the metal weak stars and showing that the method could be used for an exhaustive search for high velocity stars.

Novae in the Magellanic Clouds

1979 ◽  
Vol 46 ◽  
pp. 96-101
Author(s):  
J.A. Graham
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
University Of Michigan ◽  
The Past ◽  
Spectroscopic Information ◽  
Objective Prism ◽  
The University ◽  
Small Cloud ◽  
Low Dispersion

During the past several years, a systematic search for novae in the Magellanic Clouds has been carried out at Cerro Tololo Inter-American Observatory. The Curtis Schmidt telescope, on loan to CTIO from the University of Michigan is used to obtain plates every two weeks during the observing season. An objective prism is used on the telescope. This provides additional low-dispersion spectroscopic information when a nova is discovered. The plates cover an area of 5°x5°. One plate is sufficient to cover the Small Magellanic Cloud and four are taken of the Large Magellanic Cloud with an overlap so that the central bar is included on each plate. The methods used in the search have been described by Graham and Araya (1971). In the CTIO survey, 8 novae have been discovered in the Large Cloud but none in the Small Cloud. The survey was not carried out in 1974 or 1976. During 1974, one nova was discovered in the Small Cloud by MacConnell and Sanduleak (1974).

scholarly journals The Age of Old Galactic Populations

1998 ◽  
Vol 11 (1) ◽  
pp. 560-561
Author(s):  
M. Grenon
Keyword(s):  
High Velocity ◽  
Radial Velocities ◽  
Thick Disk ◽  
Early Evolution ◽  
Galactic Bulge ◽  
Colour Class ◽  
The Galaxy ◽  
Nearby Stars

As a preparation to the HIPPARCOS mission, a large observing programme on NLTT stars (propermotion > 0.18 ″/yr) was started in Genevaphotometry. The original programme consists of 10047 stars brighter than mR = 11.5, or mR = 12.5 if of colour class m. Among them, 7813 targets could be included in the HIPPARCOS programme, selected according to their observability and internal priorities in favour of large parallaxe stars (photometric distances < 100 pc) and high-velocity stars. The bulk of new nearby, halo, mild-metal poor and SMR stars in the HIP Catalogue originates from this proposal (N° 139). No less than 208 new nearby stars with π ≥ 40 mas were discovered south of δ +10°, the closest has π(HIP)= 182 mas. Radial velocities were obtained with CORAVEL at OHP and ESO. Most aspects of the early evolution of the Galaxy may be addressed with this sample. Here we discuss, as examples, the ages of the thick disk and of the galactic bulge.

scholarly journals 3D optical spectroscopic study of NGC 3344 with SITELLE: I. Identification and confirmation of supernova remnants

2019 ◽  
Vol 488 (1) ◽  
pp. 803-829 ◽  
Author(s):  
I Moumen ◽  
C Robert ◽  
D Devost ◽  
R P Martin ◽  
L Rousseau-Nepton ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Flux Ratio ◽  
Large Magellanic Cloud ◽  
Emission Lines ◽  
Ionization Mechanism ◽  
H Ii Regions ◽  
Nearby Galaxy ◽  
Galactocentric Distance ◽  
Ionized Gas ◽  
Diffuse Ionized Gas

ABSTRACT We present the first optical identification and confirmation of a sample of supernova remnants (SNRs) in the nearby galaxy NGC 3344. Using high spectral and spatial resolution data, obtained with the CFHT imaging Fourier transform spectrograph SITELLE, we identified about 2200 emission line regions, many of which are H ii regions, diffuse ionized gas regions, and also SNRs. Considering the stellar population and diffuse ionized gas background, which are quite important in NGC 3344, we have selected 129 SNR candidates based on four criteria for regions where the emission lines flux ratio [S ii]/H α ≥ 0.4. Emission lines of [O ii] λ3727, H β, [O iii] λλ4959,5007, H α, [N ii] λλ6548,6583, and [S ii] λλ6716,6731 have been measured to study the ionized gas properties of the SNR candidates. We adopted a self-consistent spectroscopic analysis, based on Sabbadin plots and Baldwin, Phillips & Terlevich diagrams, to confirm the shock-heated nature of the ionization mechanism in the candidates sample. With this analysis, we end up with 42 Confirmed SNRs, 45 Probable SNRs, and 42 Less likely SNRs. Using shock models, the confirmed SNRs seem to have a metallicity ranging between Large Magellanic Cloud and 2×solar. We looked for correlations between the size of the confirmed SNRs and their emission lines ratios, their galaxy environment, and their galactocentric distance: We see a trend for a metallicity gradient among the SNR population, along with some evolutionary effects.

scholarly journals Is High-Velocity Cloud Complex C Associated with the Galactic Warp?

2003 ◽  
Vol 20 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Daisuke Kawata ◽  
Christopher Thom ◽  
Brad K. Gibson
Keyword(s):  
High Latitude ◽  
High Velocity ◽  
Large Magellanic Cloud ◽  
Alternative Interpretation ◽  
North Polar ◽  
Gas Cloud ◽  
Cloud Complex ◽  
Galactic Warp ◽  
Velocity Cloud ◽  
Spiral Arm

AbstractWe test the hypothesis that high-velocity gas cloud Complex C is actually a high-latitude spiral arm extension in the direction of the Galactic warp, as opposed to the standard interpretation — that of a once extragalactic, but now infalling, gas cloud. A parallel Tree N-body code was employed to simulate the tidal interaction of a satellite perturber with the Milky Way. We find that a model incorporating a perturber of the mass of the Large Magellanic Cloud on a south to north polar orbit, crossing the disk at ˜15 kpc, does yield a high-velocity, high-latitude extension consistent with the spatial, kinematical, and column density properties of Complex C. Unless this massive satellite remains undiscovered because of either a fortuitous alignment with the Galactic bulge (feasible within the framework of the model), or the lack of any associated baryonic component, we conclude that this alternative interpretation appears unlikely.

scholarly journals Spectroscopic Observations of the Early-Type Contact Binary AW Lacertae

1989 ◽  
Vol 107 ◽  
pp. 354-354
Author(s):  
Y. Nakamura ◽  
A. Okazaki ◽  
J. Katahira
Keyword(s):  
Spectral Type ◽  
Variable Stars ◽  
Radial Velocities ◽  
Early Type ◽  
Mass Ratio ◽  
Photometric Analysis ◽  
Spectroscopic Observations ◽  
Type Contact ◽  
Contact Binary ◽  
Photometric Solution

Abstract.Spectroscopic observations were performed of the early-type contact binary AW Lac with an image-intensified coude spectrograph of 1.9−m telescope at the Okayama Astro-physical Observatory. A total of twenty-two spectra covering blue region with a dispersion of 16 Amm−1 have been secured on Kodak IIa-O baked plates. In every spectra sharp interstellar Call H,K lines are clearly seen. The spectral type of AW Lac has been estimated as early B, which substantially confirms the one adopted in the photometric analysis by Jiang et al. (1983) and is diffrent from A0 listed in General Catalogue of Variable Stars (Kholopov et al. 1985). Contrary to the suggestion by the photometric solution of Jiang et al., no definite secondary lines could be separated, though some indications of light contamination due to the secondary component are surely observed. This would imply that the light ratio of the components should be somewhat smaller than that derived by photometric analysis. No emission features appeared either. The measurement of radial velocities of the primary component for the orbital elements was made for twenty spectra by a conventional method. It was difficult to measure the radial velocities because the lines are quite broadened and deformed. Hence the measured values for the radial velocities should be regarded as rather preliminary. The derived spectroscopic elements, combined with the photometric data, give the absolute dimensions of the system for each assumed mass ratio q. For q = 1, being the adopted photometric solution by Jiang et al., we obtain too small value for the primary’s mass, comparing with its spectral type. For the mass ratio as small as q = 0.6, we can obtain a reasonable value for the mass of the primary. However, in order to get more definite conclusion the cross-correlation method would be more appropriate for the spectroscopic analysis of this system.

PROPERTIES AND ORIGIN OF THE HIGH-VELOCITY GAS TOWARD THE LARGE MAGELLANIC CLOUD

2009 ◽  
Vol 702 (2) ◽  
pp. 940-954 ◽  
Author(s):  
N. Lehner ◽  
L. Staveley-Smith ◽  
J. C. Howk
Keyword(s):  
High Velocity ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud

scholarly journals Study of Spectroscopic Binaries with the Objective Prism Method

1983 ◽  
Vol 62 ◽  
pp. 104-107
Author(s):  
Frank Gieseking
Keyword(s):  
Radial Velocity ◽  
Frequency Distribution ◽  
Radial Velocities ◽  
Spectroscopic Binaries ◽  
Steep Decrease ◽  
Visual Magnitude ◽  
Objective Prism ◽  
The Individual ◽  
Large Telescopes

The frequency distribution of SB’s over apparent visual magnitude emerging from the catalogue of Batten et. al. (1978) shows a very steep decrease of the number of spectroscopically detected SB’s already for such bright stars of magnitude 7. Considering the number of all stars in the individual magnitude intervals, we find a kind of completeness parameter of the spectroscopic surveys: If we scale it somewhat optimistically at 100% between 0 and 3 mag, we see a 50% decrease of the completeness of our knowledge of stellar radial velocities already for stars fainter than 4.5 mag.This situation is mainly due to the fact that the measurement of radial velocities with conventional slit spectrographs is extremely laborious, requiring long exposure times at large telescopes for the exposure of only one spectrum at a time. – Therefore more efficient methods for radial velocity determinations of fainter stars are urgently needed.

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