R Andromedae

Last updated
R Andromedae
Andromeda IAU.svg
Red circle.svg
Location of R Andromedae (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Andromeda
Right ascension 00h 24m 01.946s [1]
Declination +38° 34 37.37 [1]
Apparent magnitude  (V)5.8 - 15.2 [2]
Characteristics
Spectral type S3,5e-S8,8e(M7e) [2]
B−V color index 1.97 [3]
Variable type Mira [2]
Astrometry
Radial velocity (Rv)−6.40 [4]  km/s
Proper motion (μ)RA: −16.021±0.148 [1]   mas/yr
Dec.: −32.794±0.141 [1]   mas/yr
Parallax (π)2.6444 ± 0.1600  mas [1]
Distance 1,230 ± 70  ly
(380 ± 20  pc)
Absolute magnitude  (MV)−5.19 [5]
Details
Radius 476±120 - 493±129 [6]   R
Luminosity 6,300 [7]   L
Surface gravity (log g)−1.02 [8]   cgs
Temperature 2,500 [8]   K
Metallicity [Fe/H]−1.01 [9]   dex
Other designations
HR 90, BD +37°58, HD 1967, SAO 53860, HIP 1901.
Database references
SIMBAD data

R Andromedae (R And) 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, [10] 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. [11] The star is losing mass due to stellar winds at a rate of 1.09×10−6 M/yr. [5]

Contents

Variability

R Andromedae light curve R Andromedae light curve.png
R Andromedae light curve

R Andromedae shows periodic variations in its brightness approximately every 409 days. The maximum brightness is not the same every cycle and can reach a peak magnitude of mv = 5.8, with the lowest known minima nearly 10 magnitudes fainter. The rise to maximum brightness is approximately twice as fast as the fall to minimum brightness. It is classified as a Mira variable. Those stars contract and expand regularly, changing size and temperature, and this causes the brightness variations. [2]

Properties

R Andromedae has a spectral type that varies as its brightness changes. At a typical maximum it is assigned a spectral type of S5/4.5e. This makes it an S-type star, a red giant similar to class M stars but with unusually strong molecular bands of ZrO in its spectrum compared to the titanium oxide (TiO) bands seen in other cool giants. S stars are intermediate between carbon stars and the more typical oxygen-rich giants. The S5 indicates its relative temperature, while the number after the slash is a measure of the relative C:O ratio, 4.5 meaning carbon is about 97% as abundant as oxygen. ZrO bands in R Andromedae are about twenty times stronger than those of TiO. [12] When it is fainter, the spectral type has been classified as late as S8,8e. On this older classification system for S stars, the number after the comma is an indication of the relative strength of ZrO and TiO bands which used to be considered to show the C:O ratio. [13]

R Andromedae, like all Mira variables, is an asymptotic giant branch star, one that has exhausted its core helium and is burning it in a shell outside the core and hydrogen in a shell closer to the surface. These stars undergo dredge-up events which cause convection of fusion products to the surface and anomalies such as enhanced carbon and zirconium. Asymptotic giant branch stars are very cool and luminous red giants; R Andromedae varies in temperature and luminosity but is typically about 2,500 K and 6,300  L. The angular diameter of R Andromedae has been measured at 8.63±1.42  mas and 8.32±1.27 mas on different dates, corresponding to radii of 493±129 R and 476±120 R respectively, assuming a distance of 532  pc . [6]

Related Research Articles

<span class="mw-page-title-main">Chi Cygni</span> Star in the constellation Cygnus

Chi Cygni is a Mira variable star in the constellation Cygnus, and also an S-type star. It is around 500 light years away.

<span class="mw-page-title-main">28 Andromedae</span> Star in the constellation Andromeda

28 Andromedae is a Delta Scuti variable star in the constellation Andromeda. 28 Andromedae is the Flamsteed designation. It also bears the variable star name GN Andromedae. Its apparent magnitude is 5.214, varying by less than 0.1 magnitudes.

<span class="mw-page-title-main">63 Andromedae</span> Star in the constellation Andromeda

63 Andromedae is an Alpha2 Canum Venaticorum variable star in the constellation Andromeda. Its variable star designation is PZ Andromedae. With an apparent magnitude of about 5.6, it is bright enough to be seen by naked eye. Based upon an annual parallax shift of 8.53 mas, it is located 382 light years away.

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

R Horologii is a red giant star approximately 760 light-years away in the southern constellation of Horologium. It is a Mira variable with a period of 404.83 days, ranging from apparent magnitude 4.7 to 14.3—one of the largest ranges in brightness known of stars in the night sky visible to the unaided eye. The star is losing mass at the rate of 5.9×10−7 M·y−1.

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

R Centauri is a Mira variable star in the constellation Centaurus.

Z Andromedae is a binary star system consisting of a red giant and a white dwarf. It is the prototype of a type of cataclysmic variable star known as symbiotic variable stars or simply Z Andromedae variables. The brightness of those stars vary over time, showing a quiescent, more stable phase and then an active one with a more pronounced variability and stronger brightening and/or dimming.

<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.

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

T Andromedae is a variable star of the Mira type in the constellation Andromeda. Like all the stars of this kind, T And is a cool asymptotic giant branch star of spectral type M4e-M7.5e. Its brightness varies periodically, completing a cycle in 281 days. The peak luminosity, however, is different every variability cycle, but can reach a peak magnitude mv=7.70.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.

<span class="mw-page-title-main">NO Aurigae</span> Star in the constellation Auriga

NO Aurigae is a pulsating variable star in the constellation Auriga. It is an unusually-luminous asymptotic giant branch star about 3,500 light years away.

<span class="mw-page-title-main">S-type star</span> Cool giant with approximately equal quantities of carbon and oxygen in its atmosphere

An S-type star is a cool giant with approximately equal quantities of carbon and oxygen in its atmosphere. The class was originally defined in 1922 by Paul Merrill for stars with unusual absorption lines and molecular bands now known to be due to s-process elements. The bands of zirconium monoxide (ZrO) are a defining feature of the S stars.

<span class="mw-page-title-main">TX Piscium</span> Carbon star visible to the naked eye in the constellation Pisces

TX Piscium is a variable red giant star in the constellation Pisces. It is amongst the reddest naked eye stars, with a significant reddish hue when seen in binoculars. It is approximately 800 light years from Earth.

<span class="mw-page-title-main">WOH G64</span> Red supergiant in the constellation Dorado

WOH G64 is an unusual red supergiant (RSG) star in the Large Magellanic Cloud (LMC) satellite galaxy in the southern constellation of Dorado. It is one of the largest known stars, being described as possibly being the largest star known. It is also one of the most luminous and massive red supergiants, with a radius calculated to be around 1,540 times that of the Sun (R) and a luminosity around 282,000 times the solar luminosity (L).

<span class="mw-page-title-main">W Andromedae</span> Variable star in the constellation Andromeda

W Andromedae is a variable star in the constellation of Andromeda. It is classified as a Mira variable and S-type star, and varies from an apparent visual magnitude of 14.6 at minimum brightness to a magnitude of 6.7 at maximum brightness, with a period of approximately 397.3 days. The star is losing mass due to stellar winds at a rate of 2.79×10−7M/yr.

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

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.

<span class="mw-page-title-main">S Canis Minoris</span> Variable star in the constellation Canis Minor

S Canis Minoris is a variable star in the equatorial constellation Canis Minor. It has a peak apparent visual magnitude of 6.5, so not normally visible to the naked eye. The star is located at a distance of approximately 1,530 light-years from the Sun based on stellar parallax, and is drifting further away with a radial velocity of about +68 km/s.

<span class="mw-page-title-main">TV Geminorum</span> Star in the constellation Gemini

TV Geminorum is a variable red supergiant in the constellation Gemini. Its visual magnitude varies from 6.3 to 7.5.

<span class="mw-page-title-main">S Cassiopeiae</span> Star in the constellation Cassiopeia

S Cassiopeiae is a Mira variable and S-type star in the constellation Cassiopeia. It is an unusually cool star, rapidly losing mass and surrounded by dense gas and dust producing masers.

<span class="mw-page-title-main">IK Tauri</span> Mira variable star in the constellation Taurus

IK Tauri or NML Tauri is a Mira variable star located about 280 parsecs (910 ly) from the Sun in the zodiac constellation of Taurus.

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

TU Andromedae is a variable star of the Mira type in the constellation Andromeda. It has a spectral type of M5e and a visual magnitude which varies between extremes of 7.6 and 13.5.

References

  1. 1 2 3 4 5 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. 1 2 3 4 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. "R And". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved October 7, 2018.
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012). "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project". Astronomy & Astrophysics. 546: 14. arXiv: 1208.3048 . Bibcode:2012A&A...546A..61D. doi:10.1051/0004-6361/201219219. S2CID   59451347. A61.
  5. 1 2 Guandalini, R. (April 2010). "Infrared photometry and evolution of mass-losing AGB stars. III. Mass loss rates of MS and S stars". Astronomy and Astrophysics. 513: A4. arXiv: 1002.2458 . Bibcode:2010A&A...513A...4G. doi:10.1051/0004-6361/200911764. S2CID   119193286.
  6. 1 2 van Belle, G. T.; et al. (1997). "Angular Size Measurements of Carbon Miras and S-Type Stars". The Astronomical Journal. 114 (5): 2150–2156. Bibcode:1997AJ....114.2150V. doi:10.1086/118635.
  7. Ramstedt, S.; Olofsson, H. (2014). "The12CO/13CO ratio in AGB stars of different chemical type". Astronomy & Astrophysics. 566: A145. arXiv: 1405.6404 . Bibcode:2014A&A...566A.145R. doi:10.1051/0004-6361/201423721. S2CID   59125036.
  8. 1 2 Ortiz, Roberto; Guerrero, Martín A. (2016). "Ultraviolet emission from main-sequence companions of AGB stars". Monthly Notices of the Royal Astronomical Society. 461 (3): 3036. arXiv: 1606.09086 . Bibcode:2016MNRAS.461.3036O. doi: 10.1093/mnras/stw1547 . S2CID   118619933.
  9. Gáspár, András; Rieke, George H.; Ballering, Nicholas (2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal. 826 (2): 171. arXiv: 1604.07403 . Bibcode:2016ApJ...826..171G. doi: 10.3847/0004-637X/826/2/171 . S2CID   119241004.
  10. Merrill, P. W. (1952). "Technetium in the stars". Science . 115 (2992): 479–489 [484]. Bibcode:1952Sci...115..479.. doi:10.1126/science.115.2992.479. PMID   17792758.
  11. Yamamura, Issei; et al. (January 2000). "Identification of SH ∆v=1 Ro-vibrational Lines in R Andromedae". The Astrophysical Journal. 528 (1): L33–L36. arXiv: astro-ph/9911080 . Bibcode:2000ApJ...528L..33Y. doi: 10.1086/312420 . PMID   10587489.
  12. Keenan, P. C.; Boeshaar, P. C. (1980). "Spectral types of S and SC stars on the revised MK system". The Astrophysical Journal Supplement Series. 43: 379. Bibcode:1980ApJS...43..379K. doi: 10.1086/190673 .
  13. Keenan, Philip C.; Garrison, Robert F.; Deutsch, Armin J. (1974). "Revised Catalog of Spectra of Mira Variables of Types ME and Se". The Astrophysical Journal Supplement Series. 28: 271. Bibcode:1974ApJS...28..271K. doi: 10.1086/190318 .