RS Cancri

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RS Cancri
RSCncLightCurve.png
A visual band light curve for RS Cancri, plotted from AAVSO data [1]
Observation data
Epoch J2000       Equinox J2000
Constellation Cancer
Right ascension 09h 10m 38.79702s [2]
Declination +30° 57′ 47.2911″ [2]
Apparent magnitude  (V)5.4 - 7.3 [3]
Characteristics
Spectral type M6S [4]
Variable type SRb [3]
Astrometry
Proper motion (μ)RA: −10.723±0.423 [2]   mas/yr
Dec.: −33.822±0.360 [2]   mas/yr
Parallax (π)6.6490 ± 0.4946  mas [2]
Distance 490 ± 40  ly
(150 ± 10  pc)
Absolute magnitude  (MV)5.4 - 7.3 [3]
Details
Radius 225 [5]   R☉
Luminosity 4950 [6]   L☉
Temperature 3200 [6]   K
Other designations
HD  78712, HR  3639, HIP  45058, SAO  61306 [7]
Database references
SIMBAD data

RS Cancri, also known as HR 3639 and HD 78712, is a star about 490 light years from the Earth in the constellation Cancer. It is a semiregular variable star, ranging in brightness from magnitude 5.4 to 7.3 over a period of about 229 days. During the time intervals when it is brighter than magnitude 6, it may be faintly visible to the naked eye of an observer far from city lights.

The variability of RS Cancri was discovered by Edward Pickering based upon 15 observations made in 1892 and 1898. S. Seliwanow derived a period of 129.5 days for the star, in 1923. [8] In 2005, Saul Adelman and John Dennis found that the star showed two periods well determined by their data, 121.8±0.9 and 248±7 days, as well as a poorly-determined third period of about 500 days. [9]

RS Cancri is an S-type star, [4] on the asymptotic giant branch. [10] Its spectrum shows technetium, implying the star has undegone the third dredge-up. [11] RS Cancri has a stellar wind, and is losing mass at a rate of 1.7 × 10−7 solar masses per year. [5]

RS Cancri has a circumstellar shell. It is a good target for studies of such a shell, because its rather high galactic latitude (+42 degrees) means that it is cleanly separated from the interstellar dust and gas seen along most lines of sight through the galactic plane. Dust within the shell produces far-infrared continuum emission that was resolved by IRAS . [12] Both atomic and molecular gas within the shell are also measurably extended, and have been mapped. [5]

The extensive molecular envelope surrounding RS Cancri was first detected in 1977, by Kwok-Yung (Fred) Lo and Kenneth Bechis, who used the 36 foot radio telescope on Kitt Peak to detect the J=1-0 line of carbon monoxide (CO). [13] Years later, when observations of spectral lines could be made with more sensitive equipment, it was noticed that the shapes of the spectral lines suggested that RS Cancri has two distinct stellar wind components, expanding into space at different speeds. [14] Interferometric observations have shown that the two winds consist of a ~2 km/sec wind arising from an equatorial disk within the envelope, and an ~8 km/sec bipolar wind. [15] In subsequent decades, additional molecules such as SiO, SO, SO2, H2O HCN and PN have been detected. [6]

Related Research Articles

<span class="mw-page-title-main">55 Cancri</span> Binary star with at least five exoplanets 41 light-years away

55 Cancri is a binary star system located 41 light-years away from the Sun in the zodiac constellation of Cancer. It has the Bayer designation Rho1 Cancri (ρ1 Cancri); 55 Cancri is the Flamsteed designation. The system consists of a K-type star and a smaller red dwarf.

Omicron1 Cancri, Latinised from ο1 Cancri, is a solitary, white-hued star in the zodiac constellation of Cancer. It is visible to the naked eye with an apparent visual magnitude of +5.20. Based upon an annual parallax shift of 21.87 mas as seen from Earth, this star is located around 149 light-years from the Sun. It most likely forms a co-moving pair with Omicron2 Cancri.

ω2 Cancri is a star in the zodiac constellation Cancer, located around 810 light years away from the Sun. It has the Flamsteed designation 4 Cancri; ω2 Cancri is the Bayer designation, which is Latinised to omega2 Cancri and abbreviated to ω2 Cnc or omega2 Cnc. The star is near the lower limit of visibility to the naked eye, having an apparent visual magnitude of 6.32. It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s. The position of this star near the ecliptic means it is subject to lunar occultations.

5 Cancri is a single star in the zodiac constellation of Cancer, located around 520 light years away from the Sun. It is just visible to the naked eye under good seeing conditions as a dim, blue-white hued star with an apparent visual magnitude of 5.99. This object is moving closer to the Sun with a heliocentric radial velocity of −10 km/s.

Mu<sup>1</sup> Cancri Red giant star in the constellation Cancer

Mu1 Cancri, Latinised from μ1 Cancri, is a variable star in the zodiac constellation of Cancer. The name Mu1 comes from the Bayer naming system: 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. The star is dimly visible to the naked eye with an apparent visual magnitude that ranges from 5.87 down to 6.07. Parallax measurements put it about 630 light-years (192 parsecs) from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.28. The position of the star near the ecliptic means it is subject to lunar occultations.

29 Cancri is a star in the zodiac constellation of Cancer, located 370 light years from the Sun. It is just visible to the naked eye as a dim, white-hued star with an apparent visual magnitude of 5.94. The star is situated near the ecliptic, which means it is subject to lunar occultations.

<span class="mw-page-title-main">38 Cancri</span> Star in the constellation Cancer

38 Cancri is a variable star in the zodiac constellation Cancer, located around 607 light years from the Sun. This object has the variable star designation BT Cancri; 38 Cancri is the Flamsteed designation. It is a member of the Praesepe cluster but is a challenge to view with the naked eye, having an apparent visual magnitude of 6.65. The star is moving closer to the Earth with a heliocentric radial velocity of +32 km/s.

<span class="mw-page-title-main">La Superba</span> Variable star in the constellation Canes Venatici

La Superba is a strikingly red giant star in the constellation Canes Venatici. It is a carbon star and semiregular variable.

<span class="mw-page-title-main">CW Leonis</span> Star in the constellation Leo

CW Leonis or IRC +10216 is a variable carbon star that is embedded in a thick dust envelope. It was first discovered in 1969 by a group of astronomers led by Eric Becklin, based upon infrared observations made with the 62-inch Caltech Infrared Telescope at Mount Wilson Observatory. Its energy is emitted mostly at infrared wavelengths. At a wavelength of 5 μm, it was found to have the highest flux of any object outside the Solar System.

<span class="mw-page-title-main">R Andromedae</span> Star in the constellation Andromeda

R Andromedae is a Mira-type variable star in the constellation Andromeda. Its spectral class is type S because it shows absorption bands of zirconium monoxide (ZrO) in its spectrum. It was among the stars found by Paul Merrill to show absorption lines of the unstable element technetium, establishing that nucleosynthesis must be occurring in stars. The SH molecule was found for the first time outside earth in the atmosphere of this star. The star is losing mass due to stellar winds at a rate of 1.09×10−6M☉/yr.

<span class="mw-page-title-main">T Cephei</span> Star in the constellation Cepheus

T Cephei is a Mira variable star in the constellation Cepheus. Located approximately 600 light-years distant, it varies between magnitudes 5.2 and 11.3 over a period of around 388 days.

FG Sagittae is a supergiant star in the constellation Sagitta at a distance of 4000 light-years. When first noted in 1943, it was identified to be a variable star, and it was found to be a hot, blue star of stellar spectral type B in 1955. Since then it has expanded and cooled, becoming a yellow G-type star by 1991, and then further cooling to become an orange K-type star. It started to pulsate when becoming an A-type star with a period of 15 days. This period later increased to over 100 days.

g Herculis Star in the constellation Hercules

g Herculis is a binary star system in the northern constellation of Hercules. It has the Flamsteed designation 30 Herculis, while g Herculis is the Bayer designation. This system is visible to the naked eye as a faint, red-hued point of light. Based upon a measured parallax of 9.2 mas, it is located around 354 light years away from the Sun. The system is moving further from the Earth with a heliocentric radial velocity of 1.5 km/s.

<span class="mw-page-title-main">T Ceti</span> Variable star in the constellation Cetus

T Ceti is a semiregular variable star located in the equatorial constellation of Cetus. It varies between magnitudes 5.0 and 6.9 over 159.3 days. The stellar parallax shift measured by Hipparcos is 3.7 mas, which yields a distance estimate of roughly 900 light years. It is moving further from the Earth with a heliocentric radial velocity of +29 km/s.

<span class="mw-page-title-main">X Cancri</span> Variable star in the constellation Cancer

X Cancri is a variable star in the northern constellation of Cancer. It has a red hue and is visible to the naked eye at its brightest. The distance to this object is approximately 1,860 light years based on parallax measurements, but is drifting closer with a radial velocity of −5 km/s. It lies very close to the ecliptic and so is subject to lunar occultations.

<span class="mw-page-title-main">EP Aquarii</span> Variable star in the constellation Aquarius

EP Aquarii is a semiregular variable star in the equatorial constellation of Aquarius. At its peak brightness, visual magnitude 6.37, it might be faintly visible to the unaided eye under ideal observing conditions. A cool red giant on the asymptotic giant branch (AGB), its visible light brightness varies by about 1/2 magnitude over a period of 55 days. EP Aquarii has a complex circumstellar envelope (CSE), which has been the subject of numerous studies.

<span class="mw-page-title-main">RT Virginis</span> Star in the constellation Virgo

RT Virginis is a variable star in the equatorial constellation of Virgo, abbreviated RT Vir. It ranges in brightness from an apparent visual magnitude of 7.7 down to 9.7, which is too faint to be visible to the naked eye. Based on parallax measurements made with the VLBI, the distance to this star is approximately 740 light years. It is receding from the Sun with a radial velocity of 17 km/s.

<span class="mw-page-title-main">VZ Cancri</span> Variable star in the constellation Cancer

VZ Cancri is a variable star in the constellation Cancer, abbreviated VZ Cnc. It varies in brightness with a period of 0.178364 days, from an apparent visual magnitude of 7.18 down to 7.91, which lies below the typical threshold of visibility for the naked eye. The distance to this star is approximately 724 light years based on parallax measurements, and it is receding from the Sun with a radial velocity of 25 km/s.

<span class="mw-page-title-main">R Crateris</span> Variable star in the constellation Crater

R Crateris is a star about 700 light years from the Earth in the constellation Crater. It is a semiregular variable star, ranging in brightness from magnitude 8.1 to 9.5 over a period of about 160 days. It is not visible to the naked-eye, but can be seen with a small telescope, or binoculars. R Crateris is a double star; the variable star and its magnitude 9.9 F8V companion are separated by 65.4 arcseconds.

<span class="mw-page-title-main">X Herculis</span> Variable star in the constellation Hercules

X Herculis is a star about 400 light years from the Earth in the constellation Hercules. It is a semiregular variable star, ranging in brightness from magnitude 5.8 to 7.0 over a period of about 102 days. It is rarely visible to the naked-eye, but can be seen easily with a small telescope, or binoculars.

References

  1. ↑ "Download Data". aavso.org. AAVSO. Retrieved 21 March 2023.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID   125853869.
  4. 1 2 Keenan, Philip C. (November 1954). "Classification of the S-Type Stars". Astrophysical Journal. 120: 484–505. Bibcode:1954ApJ...120..484K. doi: 10.1086/145937 .
  5. 1 2 3 Hoai, D. T.; Matthews, L. D.; Winters, J. M.; Nhung, P. T.; Gérard, E.; Libert, Y.; Le Bertre, T. (May 2014). "The multi-scale environment of RS Cancri from CO and H I observations". Astronomy and Astrophysics. 565: A54. arXiv: 1403.2163 . Bibcode:2014A&A...565A..54H. doi: 10.1051/0004-6361/201423529 .
  6. 1 2 3 Winters, J. M.; Hoai, D. T.; Wong, K. T.; Kim, W. J.; Nhung, P. T.; Tuan-Anh, P.; Lesaffre, P.; Darriulat, P.; Le Bertre, T. (February 2022). "Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB star RS Cancri". Astronomy and Astrophysics. 658: A135. arXiv: 2112.00377 . Bibcode:2022A&A...658A.135W. doi: 10.1051/0004-6361/202141662 .
  7. ↑ "V* RS Cnc -- S Star". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2023-03-21.
  8. ↑ Howarth, J. J. (December 2005). "The semi-regular variable RS Cancri: one period, two, or many?". Journal of the British Astronomical Association. 115 (6): 334–337. Bibcode:2005JBAA..115..334H.
  9. ↑ Adelman, Saul J.; Dennis, John W., III (2005). "The S-Type Asymptotic Giant Branch Stars RS Cnc, ST Her, OP Her And HR Peg". Baltic Astronomy. 14: 41–50. Bibcode:2005BaltA..14...41A.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ↑ Nhung, Pham Tuyet; Thi Hoai, Do; Winters, Jan Martin; Darriulat, Pierre; Gérard, Eric; Le Bertre, Thibaut (May 2015). "On the central symmetry of the circumstellar envelope of RS Cnc". Research in Astronomy and Astrophysics. 15 (5): 713. arXiv: 1409.5682 . Bibcode:2015RAA....15..713N. doi: 10.1088/1674-4527/15/5/008 .
  11. ↑ Lebzelter, Th.; Hron, J. (November 1999). "A search for Technetium in semiregular variables". Astronomy and Astrophysics. 351: 533–542. Bibcode:1999A&A...351..533L.
  12. ↑ Young, K.; Phillips, T. G.; Knapp, G. R. (June 1993). "Circumstellar Shells Resolved in the IRAS Survey Data. I. Data Processing Procedure, Results, and Confidence Tests". Astrophysical Journal Supplement. 86: 517–640. Bibcode:1993ApJS...86..517Y. doi: 10.1086/191789 .
  13. ↑ Lo, K. Y.; Bechis, K. P. (November 1977). "Variable 2.5 mm CO emission from chi Cygni and Mira". Astrophysical Journal. 218 (L27–L30): L27. Bibcode:1977ApJ...218L..27L. doi: 10.1086/182569 .
  14. ↑ Knapp, G. R.; Young, K.; Lee, E.; Jorissen, A. (July 1998). "Multiple Molecular Winds in Evolved Stars. I. A Survey of CO(2-1) and CO(3-2) Emission from 45 Nearby Asymptotic Giant Branch Stars". The Astrophysical Journal Supplement Series. 117 (1): 209–231. arXiv: astro-ph/9711125 . Bibcode:1998ApJS..117..209K. doi: 10.1086/313111 .
  15. ↑ Libert, Y.; Winters, J. M.; Le Bertre, T.; Gérard, E.; Matthews, L. D. (June 2010). "HI and CO in the circumstellar environment of the S-type star RS Cancri". Astronomy and Astrophysics. 515: A112. arXiv: 1003.1636 . Bibcode:2010A&A...515A.112L. doi:10.1051/0004-6361/200912731 . Retrieved 24 March 2023.
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