catalogues and names

The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version)

SKY2000 - Master Star Catalog

Smithsonian Astrophysical Observatory Star Catalog

The Washington Visual Double Star Catalog, 1996.0

Combined General Catalogue of Variable Stars (Vol. I-III)

catalogues and names

catalogues and names	Alniyat, s Sco, sig Sco, 20 Sco, HR 6084, HD 147165, SAO 184336, CD -25 11485, FK5: 607, WDS 16212-2536A
other names	Al Niyat
constellation	Scorpius

data from The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version) (Hoffleit+, 1991)

note (category: star names):

Alniyat; Al Niyat. Name applies to pair with HR 6165.

position, motion, parallax:

position (J2000)	RA: 16h 21min 11.3sec	DEC: -25° 35' 34''
position (2000.72)	RA: 16h 21min 14sec	DEC: -25° 35' 40''
position (B1900)	RA: 16h 15min 6.5sec	DEC: -25° 21' 10''
proper motion (J2000)	RA: -0.01 arcsec/a	DEC: -0.021 arcsec/a
radial velocity	3 km/s note: spectroscopic binaries note: orbital data avaible
rotational velocity	53 km/s (uncertain) (variable)
galactic coordinates	longitude: 351.31°	latitude: 17°

note (category: radial and/or rotational velocities):

ADS 10009B, -6k/s.

magnitude

visual magnitude

2.89 (V on UBV Johnson system)

spectral / color information

spectral class	B1III
B-V-magnitude	0.13
U-B-magnitude	-0.7
R-I-magnitude
IR-note	object is infrared source (NASA merged infrared catalogue, Schmitz et al., 1978)

note (category: spectra):

Stationary Ca lines. Although this star is an MK standard for class B1III, it is a variable, a multiple star, and is situated in reflection nebulosity. Component A has also been classified as B2III and B2IV; component B as B9V, B9.5V, and B8Vp. From scanner studies of composite spectra, Beavers (ApJS, 44, 489, 1980) finds ADS 10009A can be resolved into O9.5 and B7 with a magnitude difference of 1.6V.

note (category: colors):

Color excess E(B-V) = +0.40. Reddened star.

variability information

variable star identification

Sig Sco

note (category: variability):

Beta C 2.94 - 3.06B. Multiple periods, 0.2468429, 0.239671, 8.2, and 33.1d. Surrounded by HII region. Primary period varies in period of 23.2y with an amp. of 0.7 sec. Occultations indicate the variable has a 2.2 mag. fainter companion at 0".49. The duplicity had been suspected from occultations as early as 1860. Orbital period probably over 112 yrs. UV observations indicate temperature varies by 2510K and ratio max. to min. radius by 1.095.

double/multiple star system information

number of components of multiple star system	4
separation	0 arcsec
mag difference (of double or brightest multiple)	2
component ID	O

note (category: double and multiple data):

B, 8.26V, +0.25(B-V), -0.23(U-B), B9.5V at 20", optical; vsini : 54k/s. The visual primary is triple: SB, 3.3, 5.3v, sep. 0.0005" and 5.5v at 0.49", discovered by occultation.

note (category: spectroscopic binaries):

ADS 10009A, 34.23d, K 34.0k/s, V0 +2.5k/s, asini 14.9.

miscellaneous information

note (category: group membership):

Sco OB2; Sco-Cen cluster; upper Sco region; HII region S9; in reflection nebula; assoc. Sco R1.

data from SKY2000 - Master Star Catalog (Myers+ 1997)

position, motion, parallax:

position (J2000)	RA: 16h 21min 11.317sec	DEC: -25° 35' 34.17''	±0.06 arcsec	source: 15
position (2000.72)	RA: 16h 21min 14sec	DEC: -25° 35' 40''	JD: 2451809.19
proper motion (J2000)	RA: -0.0008 arcsec/a	DEC: -0.021 arcsec/a		source: 25
radial velocity	3 km/s			source: 25
galactic coord. (B1950)	longitude: 351.32°	latitude: 17°

magnitude:

visual	2.86 (observed)	source: 30
photovisual	3.1	source: 2
photographic	2.9	source: 2

spectral information:

spectral class	B1		source: 96
Morgan-Keenan	B1III		source: 25
B-magnitude	3.02 ±0.05	B-V-magnitude	0.13
U-magnitude	2.32 ±0.05	U-B-magnitude	-0.7

variability information:

source of data: 30

variability type	140
var. amplitude	0.08
var. period	0.25
var. epoch	2444451 30. July 1980, 12:00:00 UT
next max light	2451809.25 21. September 2000, 18:00:00 UT

double/multiple star system information:

source of data: 19

separation between brightest and second brightest component	0.4 arcsec
position angle	80 °

sources:

2	HD and HDE Catalogs
Cannon, A.J., and E.C. Pickering, Harvard Annals, Vols 91-99, 1918-24, Cambridge, Massachusetts: Harvard University; Cannon, A.J., Harvard Annals, Vol. 100, 1925-36, Cambridge, Massachusetts: Harvard University; and Cannon, A.J., and M. Walton Mayall, Harvard Annals, Vol. 112, 1949, Cambridge, Massachusetts: Harvard University
15	FK5, FK5 Extension and FK5 Supplement
Fricke, W., H. Schwan and T. Lederle, "Fifth Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars," Veroff. Astronomisches Recheninstitut, No. 32, Heidelberg, Germany, 1988, and Fricke, W., H. Schwan, and T.E. Corbin, "Fifth Fundamental Catalogue (FK5), Part II. The FK5 Extension," Veröff. Astronomisches Recheninstitut, No. 33, Heidelberg, Germany, 1991
19	WDS Catalog
Worley, C.E., and G.G. Douglass, Washington Catalog of Visual Double Stars 1996.0, United States Naval Observatory, 1996
25	Bright Star Catalogue, 5th edition
Hoffleit, D. and Warren, W.H. Jr., The Bright Star Catalogue, 5th Revised Edition, Version 2, 1994
30	GCVS, 4th edition
Kholopov, P.N., et al., General Catalogue of Variable Stars, fourth edition, Moscow: Nauka Publishing House, 1985-88
96	SAO or HD/HDE Catalog
Reference from Value 1 or Reference from Value 2

data from Smithsonian Astrophysical Observatory Star Catalog (SAO Staff 1966; USNO, ADC 1990)

position and proper motion:

position (B1950)	RA: 16h 18min 8.667sec	DEC: -25° 28' 28.14''	±0.006 arcsec
position (2000.72)	RA: 16h 21min 14sec	DEC: -25° 35' 39''	JD: 2451809.19
position (J2000)	RA: 16h 21min 11.315sec	DEC: -25° 35' 34.12''
proper motion B1950 (FK4)	RA: -0.0007 arcsec/a	DEC: -0.023 arcsec/a	±0.001 arcsec/a in RA ±0.001 arcsec/a in DEC
proper motion J2000 (FK5)	RA: -0.0008 arcsec/a	DEC: -0.02 arcsec/a
source of proper motion data	Determined by source catalog

magnitude:

visual	3.1 (accuracy: 2 decimals)
source of visual magnitude data	Arithmetic mean of maximum and minimum magnitudes of a variable star

spectral information:

spectral class	B1
source of spectral data	Taken from the Henry Draper Catalogue or no spectrum in source catalog.

remarks for duplicity and variability

Variable star in visual magnitude in source catalog

catalogues

source catalogue	FK4, catalogue number: 607
Durchmusterung	CD-2511485
Boss General Catalogue	21982
Henry Draper Catalogue	147165

data from The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996)

position and proper motion:

position (J2000)	RA: 16h 21.2min	DEC: -25° 36'
proper motion (J2000)	RA: -0.01 arcsec/a	DEC: -0.021 arcsec/a

double/multiple star system information:

component	year	number of measures	position angle	angular separation	magnitude of 1st component	magnitude of 2nd component	spectral class(es)	discoverer code
Aa	1976	11	112°	0.3''	2.89	-	B1	BLM
	1990		80°	0.4''
Aa-B	1783	23	270°	20.8''	2.89	8.42	-	H 121
	1959		273°	20''

discoverer information:

discoverer code	discoverer	reference
BLM	Morgan, B. et al
H 121	Herschel, W.	-

notes:

note	Aa: Sigma Sco. A is a Beta CMa-type variable with multiple periods, is a spectroscopic binary, and an occultation double. Composite spectrum; B2III+O9.5V. H IV 121.

data from Combined General Catalogue of Variable Stars (Vol. I-III) (Kholopov+ 1998)

position:

position (equinox 1950.0)

RA: 16h 18min 8.7sec

DEC: -25° 28' 28''

variability informations:

variability type	BCEP	pulsating variable star
magnitute at max. brightness	2.86
magnitute at min. brightness	2.94
photometric system	visual, photovisual or Johnson's V
epoch for maximum light [JD]	2444450.548 30. July 1980, 01:09:07 UT
period [d]	0.246839
next maximum light [JD]	2451809.312268 21. September 2000, 19:29:40 UT
rising time	50 % of period

spectral information

spectral class

B2III+O9.5V

references

to a study	the main characteristics of the star was determined by the authors themselves
to a chart/photograph	no chart is avaible, but the star is contained in the 'Cordoba Durchmusterung'

miscanellous

ID in the GCVS catalogue	73/9018
constellation	Scorpius
notes on existence	The star is equivalent to '0740001 R'.
There are notes in published catalog.

variability type description

variability type

description

BCEP

Variables of the Beta Cephei type (Beta Cep, Beta CMa), which are pulsating O8-B6 I-V stars with periods of light and radial-velocity variations in the range of 0.1 - 0.6 days and light amplitudes from 0.01 to 0.3 mag in V. The light curves are similar in shape to average radial-velocity curves but lag in phase by a quarter of the period, so that maximum brightness corresponds to maximum contraction, i.e., to minimum stellar radius. The majority of these stars probably show radial pulsations, but some (V649 Per) display nonradial pulsations; multiperiodicity is characteristic of many of these stars.