Mu1 Cancri
{{Short description|Red giant star in the constellation Cancer}}
{{DISPLAYTITLE:Mu1 Cancri}}
{{other stars by Bayer designation|Mu Cancri{{!}}μ Cancri}}
{{Starbox begin
| name = Mu1 Cancri
}}
{{Starbox image
| image = 250px
| caption = A visual band light curve for BL Cancri, plotted from data presented by Tabur et al. (2009)
}}
{{Starbox observe
| epoch = J2000.0
| constell = Cancer
| appmag_v = +5.99 ({{val|5.87|–|6.07}})
}}
{{Starbox character
| type = Asymptotic giant branch
| u-b =
| r-i =
| variable = Lb
}}
{{Starbox astrometry
| radial_v = {{Val|+29.61|0.57}}
| prop_mo_ra = −5.831
| prop_mo_dec = −9.488
| parallax = 5.4293
| p_error = 0.1351
}}
{{Starbox detail
| source =
| mass =
| radius = {{val|56.5|4.8|5.2}}
| temperature = {{val|3744|186|150|fmt=commas}}
| metal_fe =
| rotational_velocity =
| age_gyr =
}}
{{Starbox catalog
| names = {{odlist | B=μ1 Cnc | F=9 Cancri | V=BL Cancri | FK5=| BD=+23°1887 | HD=66875 | HIP=39659 | HR=3169 | SAO=79940 }}
}}
{{Starbox reference
| Simbad = *+9+Cnc
}}
{{starbox end}}
Mu1 Cancri, Latinised from μ1 Cancri, is a variable star in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinized from μ1 Cancri, and abbreviated Mu1 Cnc or μ1 Cnc. The "1" in the name is because (from Earth) it appears to be close to 10 Cancri, or Mu2 Cancri. It is also known by the variable star designation BL Cancri, or BL Cnc. This star is dimly visible to the naked eye with an apparent visual magnitude that ranges from 5.87 down to 6.07. The position of the star near the ecliptic means it is subject to lunar occultations.
Parallax measurements put this star at about {{convert|184|pc|ly|order=flip|abbr=off|lk=on}} from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.28 due to interstellar dust. It is drifting further away with a line of sight velocity of +30 km/s.
The star Mu1 Cancri is an evolved red giant currently on the asymptotic giant branch with a stellar classification of M3 III. The lack of technetium-99 in the spectrum indicates it has not yet gone through third dredge-up. The star has expanded to 57 times the radius of the Sun and it is radiating 565 times the Sun's luminosity from its enlarged photosphere at an effective temperature of {{Val|3774|fmt=commas|ul=K}}.
In 1967, Olin J. Eggen announced his discovery that Mu1 Cancri is a variable star. It was given its variable star designation in 1972. It is a slow irregular variable with thermal pulsation periods of 22.6, 37.8 and 203.7 days.
References
{{reflist|refs=
{{Cite Gaia DR2 | 680089968036743936
| mode=cs2 | postscript. | access-date=2025-06-24 }}
{{Cite Gaia DR3 | 680089968037163392
| mode=cs2 | postscript. | access-date=2025-06-24 }}
{{citation | postscript=. | display-authors=1
| last1=Kukarkin | first1=B. V. | last2=Kholopov | first2=P. N.
| last3=Kukarkina | first3=N. P. | last4=Perova | first4=N. B.
| title=58th Name-List of Variable Stars | journal=Information Bulletin on Variable Stars
| date=September 1972 | volume=717 | pages=1–36 | bibcode=1972IBVS..717....1K
| url=https://ibvs.konkoly.hu/pub/ibvs/0701/0717.pdf | access-date=31 December 2024}}
| last=Eggen | first=O. J.
| title=Narrow and broad band photometry of red stars : I. Northern giants
| journal= The Astrophysical Journal Supplement Series| date=September 1967 | volume=14 | pages=307–358
| doi=10.1086/190158 | bibcode=1967ApJS...14..307E
| url=https://articles.adsabs.harvard.edu/pdf/1967ApJS...14..307E | access-date=31 December 2024}}
| 39659 | mode=cs2 | postscript. | access-date=2025-06-24 }}
| title=Technetium and the third dredge up in AGB stars. I. Field stars
| last1=Lebzelter | first1=T. | last2=Hron | first2=J.
| journal=Astronomy and Astrophysics
| volume=411 | pages=5335–42 | date=December 2003
| issue=3 | doi=10.1051/0004-6361:20031458 | bibcode=2003A&A...411..533L
| arxiv=astro-ph/0310018 | s2cid=18879265 | postscript=. }}
| display-authors=1 | last1=Famaey | first1=B.
| last2=Jorissen | first2=A. | last3=Luri | first3=X.
| last4=Mayor | first4=M. | last5=Udry | first5=S.
| last6=Dejonghe | first6=H. | last7=Turon | first7=C.
| title=Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
| journal=Astronomy and Astrophysics
| volume=430 | issue=1 | pages=165–186 | date=January 2005
| doi=10.1051/0004-6361:20041272 | bibcode=2005A&A...430..165F
| arxiv=astro-ph/0409579 | s2cid=17804304 | postscript=. }}
| last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C.
| title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project
| journal=Astronomy & Astrophysics
| volume=546 | id=A61 | pages=14 | date=October 2012
| doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D
| arxiv=1208.3048 | s2cid=59451347 | postscript=. }}
| title=Long-term photometry and periods for 261 nearby pulsating M giants
| last1=Tabur | first1 =V. | last2=Bedding | first2=T. R. | author2-link= Tim Bedding
| journal=Monthly Notices of the Royal Astronomical Society
| volume= 400 | issue=4 | pages=1945–61 | year=2009
| doi=10.1111/j.1365-2966.2009.15588.x | doi-access=free | bibcode=2009MNRAS.400.1945T
| arxiv=0908.3228 | s2cid=15358380 | postscript=. }}
| title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system
| journal=CDS/ADC Collection of Electronic Catalogues
| volume=2237 | year=2002 | last1=Ducati | first1=J. R.
| bibcode=2002yCat.2237....0D | postscript=. }}
| title=mu.01 Cnc
| access-date=2017-06-17 | postscript=. | mode=cs2 }}
| last=Eggen | first=Olin J.
| title=Asymptotic giant branch stars near the sun
| journal=Astronomical Journal | postscript=.
| volume=104 | issue=1 | date=July 1992 | pages=275–313
| doi=10.1086/116239 | bibcode=1992AJ....104..275E }}
| title=Rosemary Hill Observatory Lunar Occultation Summary for 1983-1984
| last1=Schneider | first1=Glenn | last2=Anderson | first2=Chris
| journal=Publications of the Astronomical Society of the Pacific
| volume=105 | page=367 | date=April 1993 | postscript=.
| doi=10.1086/133163 | bibcode=1993PASP..105..367S | s2cid=123581239 }}
{{citation | display-authors=1
| title=General catalogue of variable stars: Version GCVS 5.1
| last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V
| last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N
| last5=Pastukhova | first5=E. N | journal=Astronomy Reports
| volume=61 | issue=1 | pages=80 | year=2017
| bibcode=2017ARep...61...80S | s2cid=125853869
| doi=10.1134/S1063772917010085 | postscript=. }}
| title=Technetium and the third dredge up in AGB stars. I. Field stars
| last1=Lebzelter | first1=T. | last2=Hron | first2=J.
| journal=Astronomy and Astrophysics
| volume=411 | pages=533–542 | date=December 2003
| issue=3 | doi=10.1051/0004-6361:20031458 | arxiv=astro-ph/0310018
| bibcode=2003A&A...411..533L | s2cid=18879265 | postscript=.
}} See CncBL in Table 2.
| title=Spectral calibration of K-M giants from medium-resolution near-infrared HK-band spectra
| last1=Ghosh | first1=Supriyo | last2=Mondal | first2=Soumen
| last3=Das | first3=Ramkrishna | last4=Khata | first4=Dhrimadri
| display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society
| volume=484 | issue=4 | pages=4619–4634 | date=April 2019
| doi=10.1093/mnras/stz299 | doi-access=free | arxiv=1901.09170
| bibcode=2019MNRAS.484.4619G | s2cid=119462500 }}
}}
{{Stars of Cancer|state=collapsed}}
{{DEFAULTSORT:Mu1 Cancri}}
Category:Slow irregular variables
Category:Asymptotic-giant-branch stars
Category:Cancer (constellation)