A first catalogue of automatically selected ultraviolet-excess sources from the UVEX survey

Savage et al. (1977) found that the radio source PKS 1448-232 coincided with a stellar object of about magnitude 16.4 having an ultraviolet excess. A low resolution spectrum obtained with the Anglo-Australian Telescope (AAT) confirmed this object as a QSO with zem = 2.22 and revealed many absorption lines short-ward of the La emission. Consequently this object was included in a programme of spectroscopy at intermediate resolution with the AAT to investigate QSO absorption lines. Savage et al. have given a finding chart with an optical position of 14h48m09s.3, −23°17′10″ (1950.0). The radio fluxes are 0.40 Jy at 2.7 GHz and 0.31 Jy at 5.0 GHz.

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An abundance analysis of AK Sco, a Herbig Ae SB2 system with a magnetic component

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319003831 ◽

2018 ◽

Vol 14 (A30) ◽

pp. 133-133

Author(s):

Swetlana Hubrig ◽

Fiorella Castelli ◽

Silva P. Järvinen

Keyword(s):

Magnetic Field ◽

Special Interest ◽

Weak Magnetic Field ◽

Main Sequence ◽

Secondary Component ◽

Magnetic Component ◽

Ultraviolet Excess ◽

High Eccentricity ◽

Solar Abundance ◽

Herbig Ae Stars

AbstractAK Sco is an SB2 system formed by two nearly identical Herbig Ae stars, with Teff = 6500K and log g = 4.5, surrounded by a circumbinary disk. This actively accreting system is of special interest among the pre-main-sequence binaries because of its prominent ultraviolet excess and the high eccentricity of its orbit. Moreover, recent spectropolarimetric observations using HARPSpol indicate the presence of a weak magnetic field in the secondary component (Järvinen et al. 2018). An abundance analysis of both components has shown that all elements have a solar abundance in the two stars, except for Li and Ba. These elements are enhanced by 2.2 and 0.5 dex, respectively, in the A component and by 2.4 and 0.5 dex, respectively, in the B component.

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The Environments of Markarian Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100005042 ◽

1990 ◽

Vol 124 ◽

pp. 165-167

Author(s):

John W. MacKenty ◽

Brian McLean ◽

Caroline Simpson

Keyword(s):

Hubble Space Telescope ◽

Ultraviolet Excess ◽

Nuclear Activity ◽

Space Telescope ◽

Star Catalog ◽

Guide Star ◽

The Relationship ◽

Peculiar Galaxies

The extensively studied Markarian sample of 1500 ultraviolet excess galaxies contains many Seyfert, starburst, and peculiar galaxies. Using the 20 minute V plates obtained for the construction of the Hubble Space Telescope Guide Star Catalog, we have investigated the morphologies of the Markarian galaxies and the environments in which they are located. This paper reports on the relationship between the types of nuclear activity and the morphologies and environments of the Markarian galaxies.

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The Hertzsprung-Russell Diagram of Metal-Poor Disk Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900145644 ◽

1978 ◽

Vol 80 ◽

pp. 273-276

Author(s):

Sidney van den Bergh

Keyword(s):

Velocity Field ◽

Globular Cluster ◽

High Velocity ◽

Population Model ◽

Open Cluster ◽

Ultraviolet Excess ◽

Red Giants ◽

The Sun ◽

The Galaxy ◽

Red Giant

A quarter of a century ago Keenan and Keller (1953) showed that the majority of high-velocity stars near the Sun outline a Hertzsprung-Russell diagram similar to that of old Population I. This result, which did not appear to fit into Baade's (1944) two-population model of the Galaxy was ignored (except by Roman 1965) for the next two decades. Striking confirmation of the results of Keenan and Keller was, however, obtained by Hartwick and Hesser (1972). Their work appears to show that high-velocity field stars with an ultraviolet excess (which measures Fe/H) of δ(U-B) ≃ +0m.11 lie on a red giant branch that is more than a magnitude fainter than the giant branch of the strong-lined globular cluster 47 Tuc for which δ(U-B) ≃ +0m.10. Furthermore Demarque and McClure (1977) show that the red giants in the old metal poor [δ(U-B) ≃ +0m.11] open cluster NGC 2420 are significantly fainter than are those in 47 Tuc. Calculations by these authors show that the observed differences between the giants in 47 Tuc and in NGC 2420 can be explained if either (1) 47 Tuc is richer in helium than NGC 2420 by ΔY ≃ 0.1 or (2) if 47 Tuc has a ten times lower value of Z(CNO) than does NGC 2420.

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Spectrophotometric and morphological investigation of galaxies with ultraviolet excess. VIII

Astrophysics ◽

10.1007/bf01019426 ◽

1991 ◽

Vol 33 (2) ◽

pp. 394-400

Author(s):

M. A. Kazaryan ◽

�. S. Kazaryan

Keyword(s):

Ultraviolet Excess ◽

Morphological Investigation

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