4 Centauri

{{Short description|Star in the constellation Centaurus}}

{{about-distinguish|h Centauri|V945 Centauri{{!}}H Centauri}}

{{Starbox begin

| name = 4 Centauri

}}

{{Starbox observe

| epoch = J2000.0

| constell = Centaurus

| ra = {{RA|13|53|12.53953}}

| dec = {{DEC|−31|55|39.3947}}

| appmag_v = +4.73{{nowrap|(+4.72{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}} / +8.47{{cite journal|bibcode=1978A&AS...34....1N|title=Catalogue of homogeneous data in the UBV photoelectric photometric system|journal=Astronomy and Astrophysics|volume=34|pages=1|last1=Nicolet|first1=B.|year=1978}})}}

}}

{{Starbox character

| class = B6IV / Am

| b-v = −0.14{{cite journal|title=Multicolor photometry of metallic-line stars. III. A photometric catalogue|author=Mendoza, E. E.|journal=Revista Mexicana de Astronomía y Astrofísica|volume=1|page=175|date=1974|bibcode=1974RMxAA...1..175M}} Color indices accessed using SIMBAD.

| u-b = −0.56

| variable =

}}

{{Starbox astrometry

| radial_v = {{val|+5.2|2}}{{cite journal|title=General catalogue of stellar radial velocities|journal=Washington|author=Wilson, Ralph Elmer|date=1953|bibcode=1953GCRV..C......0W}}

| prop_mo_ra = -12.72

| prop_mo_dec = -9.48

| parallax = 5.12

| p_error = 0.70

| parallax_footnote =

| absmag_v = −1.66

}}

{{Starbox orbit

|reference=

|primary=4 Cen Aa

|name=4 Cen Ab

|period_unitless={{val|6.930137|0.000015|u=days}}

|periastron={{val|fmt=none||2418823.406|0.10}}

|k1={{val|21.0|1.5}}

|eccentricity={{val|0.25|0.10}}

|periarg={{val|152|17}}

}}

{{Starbox orbit

|reference=

|primary=4 Cen Ba

|name=4 Cen Bb

|period_unitless={{val|4.8390|0.0001|u=days}}

|periastron={{val|fmt=none|2442916.55|0.09}}

|k1={{val|16.9|3.5}}

|eccentricity={{val|0.05|0.02}}

|periarg={{val|51|20}}

}}

{{Starbox catalog

|names=h Cen, HD 120955, HR 5221, HIP 67786, CCDM J13532-3156{{cite simbad|title=* 4 Cen|access-date=8 February 2018}}

|component1=4 Cen A

|names1=SAO 204944, GC 18755, {{nowrap|CD−31°10729}}{{cite simbad|title=* 4 Cen A|access-date=8 February 2018}}

|component2=4 Cen B

|names2=SAO 204943, GC 18754, {{nowrap|CD−31°10727}}{{cite simbad|title=* 4 Cen B|access-date=8 February 2018}}

}}

{{Starbox reference

| Simbad=HD+120955|sn=4 Cen

| Simbad2=*+4+Cen+A|sn2=4 Cen A

| Simbad3=*+4+Cen+B|sn3=4 Cen B

}}

{{Starbox end}}

4 Centauri is a star in the constellation Centaurus. It is a blue-white B-type subgiant with an apparent magnitude of +4.75 and is approximately 640 light years from Earth.

4 Centauri is a hierarchical quadruple star system. The primary component of the system, 4 Centauri A, is a spectroscopic binary, meaning that its components cannot be resolved but periodic Doppler shifts in its spectrum show that it must be orbiting. 4 Centauri A has an orbital period of 6.927 days and an eccentricity of 0.23. Because light from only one of the stars can be detected (i.e. it is a single-lined spectroscopic binary), some parameters such as its inclination are unknown.{{cite journal|title=The Spectroscopic Binary H 4 Centauri|author=Paddock, G. F.|journal=Publications of the Astronomical Society of the Pacific|volume=29|number=167|page=56|date=1917|bibcode=1917PASP...29...56P|doi=10.1086/122588|s2cid=120812946 |url=https://zenodo.org/record/1431275}} The secondary component, is also a single-lined spectroscopic binary. It has an orbital period of 4.839 days and an eccentricity of 0.05. The secondary component is a metallic-lined A-type star. The two pairs themselves are separated by 14 arcseconds; one orbit would take at least 55,000 years.{{cite journal|title=Stellar multiplicity in the Scorpius-Centaurus association|author1=Levato, H.|author2=Malaroda, S.|author3=Morrell, N.|author4=Solivella, G.|journal=Astrophysical Journal Supplement Series|volume=64|pages=487–503|date=1987|bibcode=1987ApJS...64..487L|doi=10.1086/191204}}