| rotational_velocity2 =
| age_myr2 =
}}{{Starbox catalog
| names = HD 74389, BD+49°1766, HIP 42994
}}{{Starbox reference
| Simbad = HD+74389
}}{{Starbox end}}HD 74389 is a hierarchical triple star system approximately 362 light years from Earth. The primary, HD 74389 A, was initially listed in the Hipparcos catalog as an A0V spectral type star, but this was subsequently updated in 1990 as A2V when Sanduleak and Pesch imaged it with the Burrell Schmidt telescope at Kitt Peak.[1]The primary component is a white A-type main sequence star with an apparent magnitude of +7.48. Its furthest companion, HD 74389 B, is a DA-type white dwarf located 20.11 arcseconds west of—at least 190 AU from—HD 74389 A, and has a V magnitude of 14.62. The Digitized Sky Survey blue, red and infrared band images also show a background object about 13′′ to the north of HD 74389 A, possibly the M dwarf companion reported by Holberg et al.[2]
On August 4, 2016, NASA's Goddard Space Flight Center announced that its citizen science program, Disk Detective, discovered a debris disk orbiting the primary, making this the first disk ever discovered around a star with a companion white dwarf.[3] Cataloged as DDOI AWI00000wz, the disk temperature was observed to be at most 136 K. Although stars with white dwarf companions are common, and there are three known planetary systems with white dwarfs as distant companions (Gl 86, HD 27442, and HD 147513), no debris disks had previously been discovered with a closely associated white dwarf.[4]
References
1. ^{{cite journal |doi=10.1086/132651|title=On a possible white-dwarf companion to HD 74389|journal=Publications of the Astronomical Society of the Pacific|volume=102|pages=440|year=1990|last1=Sanduleak|first1=N.|last2=Pesch|first2=Peter|bibcode=1990PASP..102..440S}}
2. ^Holberg, J. B., Oswalt, T. D., Sion, E. M., Barstow, M. A., & Burleigh, M. R. 2013, MNRAS, 435, 2077
3. ^Kuchner, Marc. [https://blog.diskdetective.org/2016/08/04/our-first-paper-and-the-first-debris-disk-with-a-white-dwarf-companion/ "Our First Paper and the First Debris Disk with a White Dwarf Companion!"] Web blog post. Disk Detective: A Zooniverse project blog. 4 August 2016.
4. ^{{Cite journal|last1=Kuchner|first1=Marc J.|last2=Silverberg|first2=Steven M.|last3=Bans|first3=Alissa S.|last4=Bhattacharjee|first4=Shambo|last5=Kenyon|first5=Scott J.|last6=Debes|first6=John H.|last7=Currie|first7=Thayne|last8=Garcia|first8=Luciano|last9=Jung|first9=Dawoon|last10=Lintott|first10=Chris|last11=McElwain|first11=Michael|last12=Padgett|first12=Deborah L.|last13=Rebull|first13=Luisa M.|last14=Wisniewski|first14=John P.|last15=Nesvold|first15=Erika|last16=Schawinski|first16=Kevin|last17=Thaller|first17=Michelle L.|last18=Grady|first18=Carol A.|last19=Biggs|first19=Joseph|last20=Bosch|first20=Milton|last21=Cernohous|first21=Tadeás|last22=Luca|first22=Hugo A. Durantini|last23=Hyogo|first23=Michiharu|last24=Wah|first24=Lily Lau Wan|last25=Piipuu|first25=Art|last26=Piñeiro|first26=Fernanda|title=Disk Detective: Discovery of New Circumstellar Disk Candidates through Citizen Science|journal=The Astrophysical Journal|volume=830|issue=2|pages=84|arxiv=1607.05713 |date=19 July 2016|doi=10.3847/0004-637X/830/2/84|bibcode=2016ApJ...830...84K}}
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7. ^1 2 {{cite journal|bibcode=1986A&AS...65..405O|title=UBV photometry of stars whose positions are accurately known. III|journal=Astronomy and Astrophysics Supplement Series|volume=65|pages=405|author1=Oja|first1=T.|year=1986}}
8. ^1 2 3 4 {{cite journal|bibcode=2013MNRAS.435.2077H|title=Where are all the Sirius-like binary systems?|journal=Monthly Notices of the Royal Astronomical Society|volume=435|issue=3|pages=2077|author1=Holberg|first1=J. B.|last2=Oswalt|first2=T. D.|last3=Sion|first3=E. M.|last4=Barstow|first4=M. A.|last5=Burleigh|first5=M. R.|year=2013|doi=10.1093/mnras/stt1433|arxiv = 1307.8047 }}
9. ^1 2 {{cite journal|bibcode= 2012MNRAS.427..343M|title= Fundamental parameters and infrared excesses of Hipparcos stars|journal= Monthly Notices of the Royal Astronomical Society|volume= 427|issue= 1|pages= 343–357|author1= McDonald|first1= I.|last2= Zijlstra|first2= A. A.|last3= Boyer|first3= M. L.|year= 2012|doi= 10.1111/j.1365-2966.2012.21873.x|arxiv = 1208.2037 }}