75 Cygni

[Lady Isabella]

Hi

While doing a routine check of SS Cygni last night, I decided to spend some time with the star 75 Cygni, a lovely M-Type star. While taking the magnification up to 400x, I thought that I could detect a very faint star on the inside edge of the first diffraction ring.

Does anyone have any up todate information regarding the P.A. and separation for the companion star.

[Doc]

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

position, motion, parallax:

position (J2000) RA: 21h 40min 11.1sec DEC: +43° 16' 26''

position (B1900) RA: 21h 36min 15.5sec DEC: +42° 49' 11''

proper motion (J2000) RA: 0.063 arcsec/a DEC: 0.016 arcsec/a

radial velocity -28 km/s

note: variable radial velocity

trigonometric parallax 0.004 arcsec

galactic coordinates longitude: 90° latitude: -7.04°

note (category: dynamical parallaxes): 0.007".

magnitude

visual magnitude 5.11

(V on UBV Johnson system)

spectral / color information

spectral class M1IIIab

B-V-magnitude 1.6

U-B-magnitude 1.9

IR-note

object is infrared source (NASA merged infrared catalogue, Schmitz et al., 1978)

variability information

variable star identification 13834

double/multiple star system information

number of components of multiple star system 3

separation 57.9 arcsec

mag difference (of double or brightest multiple) 4.2

component ID AC

note (category: double and multiple data): AB binary. B, 10.5v at 3". Component C, optical.

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

position, motion, parallax:

position (J2000) RA: 21h 40min 11.116sec DEC: +43° 16' 25.77'' ±0.22 arcsec source: 15

proper motion (J2000) RA: 0.0057 arcsec/a DEC: 0.016 arcsec/a source: 25

radial velocity -28 km/s source: 25

trigonometric parallax 0.004 arcsec - source: 25

galactic coord. (B1950) longitude: 90.01° latitude: -7.04°

magnitude:

visual 5.11 (observed) source: 25

photovisual 5.4 source: 2

spectral information:

spectral class K5 source: 96

Morgan-Keenan M1IIIab source: 25

B-magnitude 6.71 ±0.05 B-V-magnitude 1.6

U-magnitude 8.61 ±0.05 U-B-magnitude 1.9

double/multiple star system information:

source of data: 19

separation between brightest and second brightest component 2.7 arcsec

magnitude difference between brightest and second brightest component 4.7

position angle 324 °

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

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: 21h 38min 13.144sec DEC: +43° 2' 46.23'' ±0.02 arcsec

position (J2000) RA: 21h 40min 11.065sec DEC: +43° 16' 25.99''

proper motion B1950 (FK4) RA: 0.0049 arcsec/a DEC: 0.022 arcsec/a ±0.004 arcsec/a in RA

±0.002 arcsec/a in DEC

proper motion J2000 (FK5) RA: 0.0052 arcsec/a DEC: 0.019 arcsec/a

source of proper motion data Determined by source catalog

magnitude:

visual 5.4 (accuracy: 2 decimals)

source of visual magnitude data Taken from Harvard or San Luis photometry.

spectral information:

spectral class K5

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

remarks for duplicity and variability

Double star in Aitken's Double Star Catalogue (Aitken 1932)

catalogues

source catalogue GC, catalogue number: 30338

Durchmusterung BD+42 4177

Boss General Catalogue 30338

Henry Draper Catalogue 206330

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

position and proper motion:

position (J2000) RA: 21h 40.2min DEC: +43° 16'

proper motion (J2000) RA: 0.063 arcsec/a DEC: 0.016 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

AB 1860 13 324° 2.7'' 5.1 9.8 M2III AC 20

AC 1875 11 254° 54.4'' 5.1 9.3 - STT 221

1975 - 61.8''

discoverer information:

discoverer code discoverer reference

AC 20 - -

STT 221 Struve, O. -

notes:

note 75 Cyg.

data from Combined General Catalogue of Variable Stars (suspected variables) (Kholopov+ 1998)

position:

position (equinox 1950.0) RA: 21h 38min 13.2sec DEC: +43° 2' 46''

variability informations:

variability type -

magnitute at max. brightness 5.11

magnitute at min. brightness

photometric system visual, photovisual or Johnson's V

spectral information

spectral class M1

references

to a study 140098D (designation: 75 CYG)

miscanellous

There are notes in the published catalog (Kukarkin et al.(1982)).

[Lady Isabella]

Thank you Doc, most helpful.

[starf]

hello all, by all accounts the AC components seem to be fairly fixed with not much change in either theta or rho since it was first measured in 1875. according to WDS 2006 the last measurement was in 2003 and there is only a 2 degree difference. According to these entries there have been 15 measurement of AB and 19 of AC but ive no idea how to access these measurements, or whether these measurements apply purely to the two dates. (maybe ian knows)

21402+4316AC 20AB 1860 1975 15 323 326 2.9 2.8 5.1 9.8 M2III +063+016 +42 4177 N D 214011.1 +431625.

21402+4316STTA221AC 1875 2003 19 255 253 54.4 62.2 5.28 10.26 +063+013 D 214011.1 +431625.

http://159.226.168.243/astrodata/ds2006/WDS2006.5/CATALOG/wdsweb_format.txt

with the main mass being a red giant (presumably on the AGB) it may have some variability like the mira variables but i cant find anything apart from a very basic entry in the GCVS (NSV 13834) - does the spectral class K5 referred to in doc's post refer to its variability? The B star is 100 times fainter and only 2.8 seconds of arc away from its giant neighbour. it must be on the limits of visibility in a small telescope and maybe even in a big one.

regards

mike

[Lady Isabella]

Hello Mike

That's a thing, I wonder if 75 Cyg has or is undergoing some form of brightness change? Or even an outburst of the component star?