75 Cygni

{{Starbox observe

| epoch = J2000

| constell = Cygnus

| ra = {{RA|21|40|11.10795}}

| dec = {{DEC|+43|16|25.8161}}

| appmag_v = 5.09

}}

{{Starbox character

| type = asymptotic giant branch

| class = M1IIIab

| b-v = {{Val|1.601|0.006}}

| u-b =

| variable = suspected

}}

{{Starbox astrometry

| radial_v = {{Val|−29.25|0.14}}

| prop_mo_ra = +62.366

| prop_mo_dec = +15.488

| parallax = 7.5210

| p_error = 0.1706

| parallax_footnote =

| absmag_v = −0.36

}}

{{Starbox detail

| mass = 1.4

| radius = 46

| luminosity = 442

| temperature = 3,906

| gravity = 1.69

| metal_fe = −0.24

| rotational_velocity =

| age_myr =

}}

{{Starbox catalog

| names = {{odlist | F=75 Cyg | BD=+42°4177 | FK=3730 | GC=30338 | HD=206330 | HIP=106999 | HR=8284 | SAO=51167 | NSV=13834 | AAVSO=2136+42 | WDS=J21402+4316 }}

}}

{{Starbox reference

| Simbad = 75+Cygni

}}

75 Cygni is a binary star system in the northern constellation of Cygnus. It is visible to the naked eye as a dim, reddish-hued point of light with an apparent visual magnitude of 5.09. The system is located at a distance of about 434 light years from the Sun, based on parallax, and is drifting closer with a radial velocity of −29 km/s.

The pair had an angular separation of {{Val|2.7|ul=arcsecond}} as of 2008, with the companion having a visual magnitude of 10.7. The brighter magnitude 5.18 primary is an aging red giant star with a stellar classification of M1IIIab. Having exhausted the supply of hydrogen at its core, it has expanded to around 46 times the radius of the Sun. It is a suspected variable star of unknown type and amplitude. The star is radiating 442 times the Sun's luminosity from its enlarged photosphere at an effective temperature of {{val|fmt=commas|3,906|ul=K}}.

It is likely that 75 Cygni is on the asymptotic giant branch, having exhausted its core helium, but there is a chance that it might be a higher-mass star on the red giant branch, before igniting its core helium.

An optical companion, with a spectral type of K, is about an arcminute away and has an apparent magnitude of 10.14.

References

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