HD 89890

{{Short description|Brightest member of a star system in the constellation Vela}}

{{Starbox begin

| name = HD 89890

}}

{{Starbox image

| image = 250px

| caption = A visual band light curve for MV Velorum, adapted from Sterken et al. (1996)

}}

{{Starbox observe

| epoch = J2000

| constell = Vela

| ra = {{RA|10|20|54.77319}}

| dec = {{DEC|−56|02|35.5728}}

| appmag_v = 4.50

}}

{{Starbox character

| type =

| class = {{nowrap|B3 III + A0 IVpSi + A2 + K0 III}}

| b-v = {{Val|−0.102|0.014}} (A + B)

| variable =

}}

{{Starbox astrometry

| radial_v = {{Val|+10.4|2.8}}

| prop_mo_ra = −7.5

| prop_mo_dec = +4.0

| parallax = 2.6564

| p_error = 0.2314

| parallax_footnote =

| absmag_v = −3.21 (A + B)

}}

{{Starbox detail

| source =

| component1 = A (HD 89890)

| mass =

| radius = {{Val|10.07|0.20}}

| luminosity = 3,082.41

| gravity = {{Val|3.00|0.03}}

| temperature = {{Val|15000|150|fmt=commas}}

| metal_fe =

| rotational_velocity = {{Val|26.8|0.5}}

| age_myr =

}}

{{Starbox catalog

| names={{odlist | WDS=J10209-5603 }}

| component1 = A+B

| names1={{odlist | HIP=50676 | HR=4074 | CPD=−55 3286 }}

| component2 = A

| names2={{odlist | B=J Velorum | HD=89890 | SAO=237959 | V=MV Velorum | TYC=8604-975-1 }}

| component3 = B

| names3={{odlist | SAO=237960 | TYC=8604-2444-1 }}

| component4 = C

| names4={{odlist | CD=-55 3306 | SAO=237958 | TYC=8604-2137-1 }}

}}

{{Starbox reference

| Simbad = HD+89890|sn=HD 89890 (A)

| Simbad2 = HIC+50676|sn2=HIC 50676 (A+B)

| Simbad3 = SAO+237960|sn3=TYC 8604-2444-1 (B)

| Simbad4 = SAO+237958|sn4=CD-55 3306 (C)

}}

HD 89890 is the brightest member of a multiple star system with at least four components, located in the southern constellation of Vela. It is visible to the naked eye with an apparent visual magnitude of 4.50. The annual parallax shift of {{Val|2.6|ul=mas}} provides a distance estimate of around {{Convert|1200|ly|pc|abbr=off|lk=on}}. It is moving further away from Earth with a heliocentric radial velocity of +10 km/s.

System

The Washington Double Star Catalog lists three visible components for this system. The brightest, component A, is of visual magnitude 4.50. Component B has a magnitude of 7.179, and as of 2000 lies at an angular separation of {{Val|7.10|ul=arcsecond}} from A, along a position angle (PA) of 102°. Component C is a magnitude 9.125 star at a separation of {{Val|36.20|u=arcsecond}} from A at a PA of 191°. The physical link between the stars was described on the basis of their dynamic parallax and mean velocities. The three components A, B and C have Gaia Data Release 2 parallaxes of {{val|2.6564|0.2314|ul=mas}}, {{val|2.1771|0.0490|u=mas}}, and {{val|1.6097|0.0400|u=mas}}, respectively.

Properties

Component A has a stellar classification of B3 III, and is categorized as a Be star. It shows photometric variations with multiple periods around 4.6 days and line-profile variations with a period of 2.318 days. The radial velocity of this star is constant. It has 10 times the Sun's radius and shines with 3,082 times the Sun's luminosity from its photosphere at an effective temperature of {{val|15000|ul=K|fmt=commas}}.

The component B shows a variation in spectra consistent with being a double-lined spectroscopic binary. The brighter member (Ba) is a silicon star with a class of A0 IVpSi, while the fainter component (Bb) is of type A2. Component C has a class of K0 III, indicating it is an evolved giant star. The measured effective temperature of C is 5,500 K. The fact that component A most likely shares a common origin with C suggests that the former is much older than expected, and may actually be a blue straggler formed from the merger of a close binary. This could have been caused by the gravitational influence of an unseen companion of A.

References

{{reflist|refs=

{{cite book|bibcode=1982IAUS...98..261J|title=Be Stars|volume=98|pages=261–263|last1=Jaschek|first1=M|last2=Egret|first2=D|last3=Jaschek|first3=M|last4=Groth|first4=H. -G|chapter=A Catalogue of be Stars |year=1982|doi=10.1007/978-94-009-8565-0_44|doi-broken-date=1 November 2024 |isbn=978-90-277-1367-4}}

{{citation

| title=XHIP: An extended hipparcos compilation

| last1=Anderson | first1=E. | last2=Francis | first2=Ch.

| journal=Astronomy Letters

| volume=38 | issue=5 | pages=331 | year=2012

| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015

| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}

{{cite journal |last1=Sterken |first1=C. |last2=Vogt |first2=N. |last3=Mennickent |first3=R. E. |title=Long-term photometry of Be stars. II. Periodic variations on time scales of days to months |journal=Astronomy and Astrophysics |date=July 1996 |volume=311 |pages=579–586 |bibcode=1996A&A...311..579S |url=https://ui.adsabs.harvard.edu/abs/1996A&A...311..579S |access-date=30 April 2022}}

{{cite journal

| title=The Tycho-2 catalogue of the 2.5 million brightest stars

| display-authors=1 | last1=Høg | first1=E.

| last2=Fabricius | first2=C. | last3=Makarov | first3=V. V.

| last4=Urban | first4=S. | last5=Corbin | first5=T.

| last6=Wycoff | first6=G. | last7=Bastian | first7=U.

| last8=Schwekendiek | first8=P. | last9=Wicenec | first9=A.

| journal=Astronomy and Astrophysics

| volume=355 | pages=L27–L30 | date=March 2000

| bibcode=2000A&A...355L..27H | doi=10.1888/0333750888/2862| isbn=978-0333750889 }}

{{citation

| title=Stellar parameters and H α line profile variability of Be stars in the BeSOS survey