HD 189276

{{Starbox observe

| epoch = J2000.0

| constell = Cygnus

| ra = {{RA|19|55|55.37920}}

| dec = {{DEC|+58|50|45.4752}}

| appmag_v = 4.98

}}

{{Starbox character

| type = red giant branch

| class = K4.5IIIa or K5II-III

| b-v = {{Val|1.584|0.011}}

| u-b =

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|+4.26|0.34}}

| prop_mo_ra = −8.953

| prop_mo_dec = −20.206

| parallax = 3.6680

| p_error = 0.0864

| parallax_footnote = {{cite Gaia EDR3|2235649675799721088}}

| absmag_v = −2.25

}}

{{Starbox detail

| source =

| mass = {{Val|4.05|0.56}}

| radius = 178.11

| luminosity = {{Val|1533|49|fmt=commas}}

| temperature = {{Val|3940|198|30|fmt=commas}}

| gravity = 1.70

| metal_fe = −0.1

| rotational_velocity = 1.7

| age_myr =

}}

{{Starbox catalog

| names = {{odlist | BD=+58°2013 | FK5=3591 | HD=189276 | HIP=98073 | HR=7633 | SAO=32122 | 2MASS=J19555536+5850454}}

}}

{{Starbox reference

| Simbad = HD+189276

}}

HD 189276 is a single star in the northern constellation Cygnus, positioned near the northern constellation border with Draco. It has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.98. The star is located at a distance of approximately 820 light years from the Sun based on parallax, and it has an absolute magnitude of −2.25. It is drifting further away with a radial velocity of +4 km/s. The star has a high peculiar velocity of {{Val|38.5|1.8|2.2|u=km/s}} and thus is a probable runaway star.

This is an aging star on the red giant branch with a stellar classification of K4.5IIIa. With the supply of hydrogen at its exhausted, it has cooled and expanded to 178 times the girth of the Sun. This is an active star that appears to be approaching the tip of the red-giant branch. Interferometric measurements of the star suggest significant departures from symmetry. HD 189276 has four times the mass of the Sun and is radiating 1,533 times the Sun's luminosity from its bloated photosphere at an effective temperature of {{val|fmt=commas|3,940|ul=K}}.

References

{{reflist|refs=

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{{citation | postscript=.

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| title=Lithium abundances and rotational behavior for bright giant stars

| display-authors=1 | journal=Astronomy and Astrophysics

| volume=450 | issue=3 | pages=1173–1179 | date=May 2006

| doi=10.1051/0004-6361:20053485 | bibcode=2006A&A...450.1173L | doi-access=free }}

{{citation

| title=Asymmetries on red giant branch surfaces from CHARA/MIRC optical interferometry

| display-authors=1 | last1=Chiavassa | first1=A.

| last2=Norris | first2=R. | last3=Montargès | first3=M.

| last4=Ligi | first4=R. | last5=Fossati | first5=L.

| last6=Bigot | first6=L. | last7=Baron | first7=F.

| last8=Kervella | first8=P. | last9=Monnier | first9=J. D.

| last10=Mourard | first10=D. | last11=Nardetto | first11=N.

| last12=Perrin | first12=G. | last13=Schaefer | first13=G. H.

| last14=ten Brummelaar | first14=T. A. | last15=Magic | first15=Z.

| last16=Collet | first16=R. | last17=Asplund | first17=M.

| journal=Astronomy & Astrophysics

| volume=600 | id=L2 | pages=5 | date=April 2017

| arxiv=1703.02406 | bibcode=2017A&A...600L...2C

| doi=10.1051/0004-6361/201730438 | s2cid=27367943 | postscript=. }}

}}

Category:K-type giants

Category:Runaway stars

Category:Cygnus (constellation)