HR 4458

{{Short description|Binary star system in the constellation Hydra}}

{{Starbox observe 2s

| constell = Hydra

| epoch = J2000

| component1 = A

| ra1 = {{RA|11|34|29.48644}}

| dec1 = {{DEC|-32|49|52.8228}}

| appmag_v1 = 5.97

| component2 = B

| ra2 = {{RA|11|34|30.47776}}

| dec2 = {{DEC|-32|50|02.4048}}

| appmag_v2 = 15

}}

{{Starbox character

| class = K0 V + DC8

| r-i = 0.40{{cn|date=March 2025}}

| v-r = 0.44{{cn|date=March 2025}}

| b-v = 0.80

| u-b = 0.325

| variable =

}}

{{Starbox astrometry

| component1 = A

| radial_v = {{val|-22.09|0.12}}

| prop_mo_ra = –670.230

| prop_mo_dec = +822.399

| pm_footnote =

| parallax = 104.6133

| p_error = 0.0277

| parallax_footnote =

| absmag_v = 6.05

| component2 = B

| radial_v2 =

| prop_mo_ra2 = –701.802

| prop_mo_dec2 = +828.928

| pm_footnote2 =

| parallax2 = 104.6570

| p_error2 = 0.0267

| parallax_footnote2 =

| absmag_v2 = 15

}}

{{Starbox detail

| component1=HR 4458 A

| mass = 0.87

| radius = 0.84

| temperature = 5,241

| gravity = 4.59

| metal_fe = −0.37

| rotational_velocity = 6.79

| luminosity_bolometric = 0.368

| age_gyr = 4.6–5.8

| component2=HR 4458 B

| mass2 = 0.58

| radius2 =

| temperature2 = 5,000

| gravity2 = 8.12

| metal_fe2 =

| rotational_velocity2 =

| luminosity_bolometric2 = 0.000088

| age_gyr2 = 5.69{{efn|name=cooling}}

}}

{{Starbox catalog

| names = {{odlist | name=289 G. Hya | F=20 Crt | GJ=432 | CD=−32°8179 | HD=100623 | HIP=56452 | HR=4458 | SAO=202583 | PLX=2678.00 | LHS=308 | LTT=4280 }}

| component2=B

| names2={{odlist | WD=1132-325}}, VB 4

}}

{{Starbox reference

| Simbad=HD+100623 |sn=A

| Simbad2=HD+100623B |sn2=B

| ARICNS=00888

}}

HR 4458 (HD 100623) is a binary star system 31.18 light-years away in the equatorial constellation of Hydra. It has the Flamsteed designation 20 Crateris and the Gould designation 289 G. Hydrae; the former refers to the constellation Crater, but when the IAU formally defined constellation boundaries, it was placed in Hydra. This object is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.97. It is moving closer to the Earth with a heliocentric radial velocity of −22 km/s.

The primary component is a K-type main-sequence star with a stellar classification of K0 V. It is around five billion years old with 84% of the Sun's radius. The star is radiating 37% of the Sun's luminosity from its photosphere at an effective temperature of 5,241 K. It has been examined for the presence of an infrared excess, but none was detected.

There is a 15th-magnitude common proper motion companion at an angular separation of {{val|16.2|ul=″}}, corresponding to a projected separation of {{Val|162.5|ul=AU}}. This is a white dwarf star with a classification of DC8. The orbital period of the pair is estimated as {{Convert|406000|days|years|disp=out|abbr=off}}.

Notes

{{notelist|refs=

}}

References

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}}

External links

{{cite web

| url =http://www.solstation.com/stars/hr4458ab.htm

| title =CD-32 8179 / HR 4458 AB

| publisher =SolStation

| access-date =2007-06-06

| archive-url =https://web.archive.org/web/20121013003737/http://www.solstation.com/stars/hr4458ab.htm

| archive-date =2012-10-13

| url-status =dead

}}

Category:K-type main-sequence stars

HR, 4458

Category:White dwarfs

Category:Binary stars

Category:Hydra (constellation)