Colour Index

2021 ◽  
pp. 1-7
Author(s):  
Geoffrey Hallas
Keyword(s):  
Colour Index

scholarly journals 523676 (2013 UL10): the first active red centaur

2018 ◽  
Vol 620 ◽  
pp. A93 ◽  
Author(s):  
E. Mazzotta Epifani ◽  
E. Dotto ◽  
S. Ieva ◽  
D. Perna ◽  
P. Palumbo ◽  
...  
Keyword(s):  
Production Rate ◽  
Canary Islands ◽  
Colour Index ◽  
Nucleus Size ◽  
Dust Production ◽  
La Palma ◽  
Upper Limit ◽  
Nucleus Surface ◽  
Perihelion Passage

Aims. We present observations of 523676 (2013 UL10), a centaur orbiting between Jupiter and Uranus that is dynamically similar to the few tens of active centaurs that are currently known. Methods. We analysed visible BVR images of the centaur obtained at the Telescopio Nazionale Galileo (La Palma, Canary Islands, Spain) to investigate the weak comet-like activity and to derive information on the nucleus surface colours and size. Results. Centaur 523676 (2013 UL10) is the only centaur known so far that has both comet-like activity and red surface colours: its nucleus has a colour index [B – R] = 1.88 ± 0.11. The nucleus R magnitude (R = 20.93 ± 0.09) allowed us to derive an upper limit for its nucleus size of D ≤ 10 km. We estimated its dust production rate to be Qd ~ 10 kg s−1 at 6.2 au (just after its perihelion passage), resulting in a timescale for the surface blanketing process τB of approximately tens of years, which is very short with respect to typical dynamical lifetime inside the group. Future monitoring of 523676 (2013 UL10) is needed to further constrain the blanketing model for active centaurs and its timescale.

scholarly journals A Large Amplitude Flaring dMe Star in the 1978 October 6B γ-ray Burst Error Box

1995 ◽  
Vol 151 ◽  
pp. 91-94
Author(s):  
J. Greiner ◽  
C. Motch
Keyword(s):  
Large Amplitude ◽  
Colour Index ◽  
Burst Error ◽  
Γ Ray

During a search for flaring optical counterparts to γ-ray burst sources (GRBs) on archival patrol plates, an optical outburst image was found in the 3200 arcmin2 error box of the GRB which occurred on 1978 October 6 (GB 781006B = GBS 0008+13; Greiner et al. 1991) and was named S 10933 according to the convention of new Sonneberg variables. This outburst image appears on three simultaneously exposed plates taken on 1966 August 14/15 from 23.33 to 0.13 UT. The brightness estimates yielded mpg = 13m.3 ± 0m.1 and mv = 13m.8 ± 0m.2 with a high negative colour index of C = −0m.5 ± 0m.3.

scholarly journals A Spiral-Like Disk of Ionized Gas in IC 1459: Signature of a Merging Collision?

1990 ◽  
Vol 124 ◽  
pp. 215-219
Author(s):  
Paul Goudfrooij ◽  
H.U. Nørgaard-Nielsen ◽  
H.E. Jørgensen ◽  
L. Hansen ◽  
T. de Jong
Keyword(s):  
Spiral Structure ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
Major Axis ◽  
Colour Index ◽  
Line Flux ◽  
Ionized Gas ◽  
The Galaxy ◽  
Merger Event ◽  
Stellar Body

AbstractWe report the discovery of a large (15 kpc diameter) Hα+[NII] emission-line disk in the elliptical galaxy IC 1459, showing weak spiral structure. The line flux peaks strongly at the nucleus and is more concentrated than the stellar continuum. The major axis of the disk of ionized gas coincides with that of the stellar body of the galaxy. The mass of the ionized gas is estimated to be ~ 1 105 M⊙, less than 1% of the total mass of gas present in IC 1459. The total gas mass of 4 107 M⊙ has been estimated from the dust mass derived from a broad-band colour index image and the IRAS data. We speculate that the presence of dust and gas in IC 1459 is a signature of a merger event.

scholarly journals Spiral structure and distribution of stellar associations in NGC 6946

1970 ◽  
Vol 38 ◽  
pp. 87-90
Author(s):  
E. Ye. Khachikian ◽  
K. A. Sahakian
Keyword(s):  
Spiral Structure ◽  
Absolute Magnitude ◽  
Colour Index ◽  
Spiral Arms ◽  
Ngc 6946 ◽  
Stellar Associations

The associations of NGC 6946 outline its spiral arms. There is no relation between the colour or magnitude of the associations and their distance from the centre. Their mean absolute magnitude is −11m.1 and their mean colour index near zero.

scholarly journals 25. Commission de Photométrie Stellaire

1939 ◽  
Vol 6 ◽  
pp. 215-228
Author(s):  
M. F. H. Seares ◽  
MM. Baade ◽  
J. Baillaud ◽  
Beljawski ◽  
A. Bemporad ◽  
...  
Keyword(s):  
Zero Point ◽  
Colour Index ◽  
Visual Magnitude ◽  
International Polar ◽  
The Mean

The committee of the Carte du Ciel in 1910 adopted the following convention : That for Ao stars between magnitudes 5·5 and 6·5 the mean photographic magnitude should equal the mean Harvard visual magnitude. As a corollary, the colour index of Ao stars would then be zero.The zero point of the photographic magnitudes of the International Polar Sequence was fixed as nearly as possible in accordance with this definition; but it was by no means certain that the magnitudes thus adopted for the few stars of the Sequence represented the zero point defined by all the Ao stars specified.

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