SU Andromedae

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SU Andromedae
SU Andromedae.jpg
SU Andromedae in optical light
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Andromeda
Right ascension 00h 04m 36.4076s [1]
Declination +43° 33′ 04.7264″ [1]
Apparent magnitude  (V)8.0 to 8.5 [2]
Characteristics
Spectral type C6,4(C5II) [2]
U−B color index +4.13 [3]
B−V color index +2.58 [3]
Variable type LC [2]
Astrometry
Proper motion (μ)RA: −3.362±0.058 [1]   mas/yr
Dec.: −2.097±0.040 [1]   mas/yr
Parallax (π)0.6979 ± 0.0439 [1]   mas
Distance 4,700 ± 300  ly
(1,430 ± 90  pc)
Absolute magnitude  (MV)−2.2 [4]
Details
SU And
Luminosity 2,535 [5]   L☉
Temperature 2,905 [5]   K
co-moving companion
Radius 1.95 [6]   R☉
Luminosity9.833 [6]   L☉
Temperature 7,311 [6]   K
Other designations
SU  Andromedae, SU And, HD  225217, HIP  363, BD+42 4827
Database references
SIMBAD data

SU Andromedae is a carbon star in the constellation of Andromeda. It is a variable star classified as a slow irregular pulsating supergiant, and varies from an apparent visual magnitude of 8.5 at minimum brightness to a magnitude of 8.0 at maximum brightness with no clear period. [2]

Contents

Variability

visual band light curve of SU Andromedae, adapted from Miles (2010) SUAndLightCurve.png
visual band light curve of SU Andromedae, adapted from Miles (2010)

Thomas Espin noted the possible variability of this star in 1895. [8] Williamina Fleming, in 1906, was examining photographic plates taken for the purpose of creating the Henry Draper Catalogue when she independently discovered and confirmed it as a variable star. [9]

Spectrum

The spectrum of SU Andromedae is dominated by Swan bands from the molecule C2. These stars were classified as type N under the Harvard scheme, stars with the blue continuum completely obscured by molecular absorption bands. Carbon star spectral types were later refined in the Morgan-Keenan system and SU Andromedae was typically classified as C64, [10] indicating a fairly cool carbon star and the subscript 4 showing modest Swan band intensity. [11]

Under the modern revised Morgan-Keenan system, SU Andromedae is classified as C-N5 C26-. [12] The C-N spectral type is to distinguish those stars from the C-R type where the blue continuum is not entirely hidden by absorption bands. A classification based on the infrared spectrum is C5 II, again a moderately cool carbon star with a luminosity class of II for a bright giant. [3]

Companion

SU Andromedae is 22" from a magnitude 12.77 star, probably an F0 main sequence star. This star has a Gaia Data Release 2 parallax of 0.7479±0.0905 [6] and an absolute magnitude of about +2.4. It has an almost identical space motion as SU Andromedae and is assumed to be a distant co-moving companion. Based on that assumption, the absolute magnitude of SU Andromedae is calculated to be about −2.2. [4]

Related Research Articles

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OU Andromedae Star in the constellation Andromeda

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HD 224801, also known as CG Andromedae, is an Alpha² Canum Venaticorum variable star in the constellation Andromeda. Located approximately 188 parsecs (610 ly) away, the star varies between apparent magnitudes 6.32 and 6.42 over a period of approximately 3.74 days.

RW Cephei Star in the constellation Cepheus

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WZ Cassiopeiae Star in the constellation Cassiopeia

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U Camelopardalis Star in the constellation Camelopardalis

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EU Andromedae Star in the constellation Andromeda

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GR Andromedae Star in the constellation Andromeda

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PX Andromedae Star in the constellation Andromeda

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V957 Scorpii

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References

  1. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.
  2. 1 2 3 4 N. N. Samus; O. V. Durlevich; et al. "SU And database entry". Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.). CDS . Retrieved 2018-10-14.
  3. 1 2 3 Richer, Harvey B. (1971). "Some Intrinsic Properties of Carbon Stars". Astrophysical Journal. 167: 521–535. Bibcode:1971ApJ...167..521R. doi:10.1086/151049.
  4. 1 2 Olson, B. I.; Richer, H. B. (1975). "The absolute magnitudes of carbon stars - Carbon stars in binary systems". Astrophysical Journal. 200: 88–94. Bibcode:1975ApJ...200...88O. doi:10.1086/153763.
  5. 1 2 Bergeat, J.; Knapik, A.; Rutily, B. (2002). "Carbon-rich giants in the HR diagram and their luminosity function". Astronomy and Astrophysics. 390 (3): 967–986. Bibcode:2002A&A...390..967B. doi: 10.1051/0004-6361:20020525 .
  6. 1 2 3 4 Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.
  7. ↑ Miles, Richard (June 2010). "SU Andromedae Light curve". British Astronomical Association Variable Star Section Circular. 144: 27. Bibcode:2010BAAVC.144...27M . Retrieved 11 October 2021.
  8. ↑ Espin, T. E. (1895). "Stars with remarkable spectra". Astronomische Nachrichten. 137 (22): 369–376. Bibcode:1895AN....137..369E. doi:10.1002/asna.18951372202.
  9. ↑ Pickering, E. C.; Fleming, W. P. (1906). "Stars having peculiar spectra. Thirteen new variable stars". Astrophysical Journal. 23: 257–261. Bibcode:1906ApJ....23..257P. doi:10.1086/141337.
  10. ↑ Skiff, B. A. (2014). "Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)". VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014). Bibcode:2014yCat....1.2023S.
  11. ↑ Keenan, Philip C.; Morgan, W. W. (1941). "The Classification of the Red Carbon Stars". Astrophysical Journal. 94: 501–510. Bibcode:1941ApJ....94..501K. doi:10.1086/144356.
  12. ↑ Barnbaum, Cecilia; Stone, Remington P. S.; Keenan, Philip C. (1996). "A Moderate-Resolution Spectral Atlas of Carbon Stars: R, J, N, CH, and Barium Stars". Astrophysical Journal Supplement. 105: 419–473. Bibcode:1996ApJS..105..419B. doi:10.1086/192323.
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