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
Mass 3.7 [6]   M☉
Radius 730 [7] [a] or 476±120 –493±129 [8]   R☉
Luminosity 6,300 [7]   L☉
Surface gravity (log g)−1.02 [9]   cgs
Temperature 1,900 –2,500 [9]   K
Metallicity [Fe/H]−1.01 [10]   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, [11] 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. [12] 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. [13] 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. [14]

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 . [8] Other measurements based on the spectral energy distribution of the star give a luminosity of 6,000 L☉ and a very cool temperature of 1,900  K , [7] which imply a very large radius of 730 R☉. [a] R Andromedae is one of the largest known stars.

Notes

  1. 1 2 Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772  K:
    .

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">Lambda Andromedae</span> Binary star system in the constellation of Andromeda

Lambda Andromedae, Latinized from λ Andromedae, is the Bayer designation for a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately 84.6 light-years from Earth, it has an apparent visual magnitude of +3.8. This is bright enough to be seen with the naked eye. The system is drifting further away from the Sun with a radial velocity of +6.8 km/s.

<span class="mw-page-title-main">8 Andromedae</span> Multiple star system in the constellation Andromeda

8 Andromedae, abbreviated 8 And, is a probable triple star system in the northern constellation of Andromeda. 8 Andromedae is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 4.82. Based upon an annual parallax shift of 5.7 mas, it is located about 570 light years from the Earth. It is moving closer with a heliocentric radial velocity of −8 km/s.

<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 Centauri</span> Variable star in the constellation Centaurus

R Centauri is a Mira variable star in the constellation Centaurus. When it is near its maximum brightness, it is faintly visible to the naked eye under very good observing conditions.

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. When it is near its maximum brightness, it is faintly visible to the naked eye under good observing conditions.

<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">OU Andromedae</span> Rotationally variable star in the constellation Andromeda

OU Andromedae is a rotationally variable star in the constellation Andromeda. Varying between magnitudes 5.87 and 5.94, it has been classified as an FK Comae Berenices variable, but the classification is still uncertain. It has a spectral classification of G1IIIe, meaning that it is a giant star that shows emission lines in its spectrum. It is also likely in its horizontal branch phase of evolution.

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

LN Andromedae, also known as HD 217811, HR 8768, is a formerly suspected variable star in the constellation Andromeda. Located approximately 458 parsecs (1,490 ly) away from Earth, it shines with an apparent visual magnitude 6.41, thus it can be seen by the naked eye under very favourable conditions. Its spectral classification is B2V, meaning that it is a hot main sequence star, emitting light approximately with a blackbody spectrum at an effective temperature of 18,090 K.

<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">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.

<span class="mw-page-title-main">RX Andromedae</span> Cataclysmic variable star system in the constellation Andromeda

RX Andromedae is a variable star in the constellation of Andromeda. Although it is classified as a dwarf nova of the Z Camelopardalis (UGZ) type, it has shown low-luminosity periods typical of VY Sculptoris stars. However, for most of the time it varies from an apparent visual magnitude of 15.1 at minimum brightness to a magnitude of 10.2 at maximum brightness, with a period of approximately 13 days.

<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">DD Microscopii</span> Star in the constellation Microscopium

DD Microscopii, also known as CD−43°14304, is a binary star system in the constellation Microscopium. The system has a combined average apparent magnitude around 11, making it readily visible in telescopes but not to the naked eye. It is thought to be at a distance of one or two thousand parsecs, although parallax measurements place the system at a distance of around 30,000 light years.

<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, making it very faintly visible to the naked eye of an observer with excellent observing conditions, when the star is near its peak brightness.

<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">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.

<span class="mw-page-title-main">EG Andromedae</span> Binary star system in the constellation Andromeda

EG Andromedae is a symbiotic binary in the constellation Andromeda. Its apparent visual magnitude varies between 6.97 and 7.80.

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. ↑ Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G.; Valentini, M.; Torralba Elipe, G.; Steinmetz, M.; Pantaleoni-González, M.; Malhotra, S.; Jiménez-Arranz, Ó.; Enke, H.; Casamiquela, L.; Ardèvol, J. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics. 691: A98. arXiv: 2407.06963 . Bibcode:2024A&A...691A..98K. doi:10.1051/0004-6361/202451427.
  7. 1 2 3 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 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.
  9. 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.
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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.
  13. ↑ 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 .
  14. ↑ 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 .
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.