7 Aquarii

{{Starbox begin

| name = 7 Aquarii

}}

{{Starbox observe

| epoch = J2000

| constell = Aquarius

| ra = {{RA|20|56|54.02626}}

| dec = {{DEC|−09|41|51.1610}}

| appmag_v = {{nowrap|5.499 (5.62 + 11.4)}}

}}

{{Starbox character

| class = K4 III

| b-v = {{Val|+1.474|0.006}}

| u-b =

| variable = Suspected

}}

{{Starbox astrometry

| radial_v = {{Val|−32.4|1.6}}

| prop_mo_ra = −5.577

| prop_mo_dec = −10.245

| parallax = 4.9495

| p_error = 0.1309

| parallax_footnote =

| absmag_v = −0.61

}}

{{Starbox detail

| source =

| mass =

| radius = 46

| luminosity = 403.66

| temperature = 3,990

| metal_fe = −0.17

| gravity = 1.650

| rotational_velocity =

| age_gyr =

}}

{{Starbox catalog

| names = {{odlist | F=7 Aqr | BD=−10°5553 | HD=199345 | HIP=103401 | HR=8015 | SAO=144968 | NSV=13419 | WDS=J20569-0942 | ADS=14449 }}

}}

{{Starbox reference

| Simbad = 7+Aqr

}}

7 Aquarii, abbreviated 7 Aqr, is a binary star system in the zodiac constellation of Aquarius. 7 Aquarii is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.5; the brighter component is baseline magnitude 5.62 while the faint secondary is magnitude 11.4. As of 2002, the pair had an angular separation of {{Val|2.10|ul=arcsecond}} along a position angle of 165°. The distance to this system, based upon an annual parallax shift of {{val|4.9|ul=mas}}, is around 660 light years. It is moving closer to the Earth with a heliocentric radial velocity of −32 km/s.

The primary component is an aging giant star with a stellar classification of K4 III. It is a suspected variable star of unknown type with a maximum magnitude of 5.48. The interferometry-measured angular diameter of this star, after correcting for limb darkening, is {{val|2.14|0.02|u=mas}}, which, at its estimated distance, equates to a physical radius of about 46 times the radius of the Sun. The star is radiating 404 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,990 K.

References

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}} The radius (R_*) is given by:

: $\begin{align} 2\cdot R_*
& = \frac{(10^{-3}\cdot 202\cdot 2.14)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& \approx 93\cdot R_{\bigodot}
\end{align}$

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