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Journal articles on the topic 'Mira variable stars'

Author: Grafiati

Published: 4 June 2021

Last updated: 20 February 2023

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1

Nakagawa, Akiharu, Tomoharu Kurayama, Toshihiro Omodaka, Tatsuya Kamezaki, Yoshiro Nishida, and Makoto Matsui. "The period–luminosity relation of Mira variable stars." Proceedings of the International Astronomical Union 8, S289 (August 2012): 217. http://dx.doi.org/10.1017/s1743921312021412.

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AbstractWe use astrometry to measure the distances to Galactic Mira variable stars. Our purpose is to determine a precise period–luminosity relation (PLR). At present, we do not have a precise PLR for Galactic Mira stars because of the large uncertainties affecting their distance estimates. To reduce the uncertainties, we adopted the Very Long Baseline Interferometry method and measured annual parallaxes of Mira variable stars with VERA. In addition to our previous results, we obtained three new distances for Mira variable stars. Based on our observations, the typical uncertainty in a given distance measurement is reduced to below 10%. At this conference, we present the current status of our project. To establish a precise Galactic PLR, we continue to observe more Mira variables. In addition, the apparent magnitudes of the target stars should be studied carefully.

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2

Castelaz, Michael W., Donald G. Luttermoser, Daniel B. Caton, and Robert A. Piontek. "Phase-dependent Spectroscopy of Mira Variable Stars." Astronomical Journal 120, no. 5 (November 2000): 2627–37. http://dx.doi.org/10.1086/316837.

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3

Luttermoser, Donald G., George H. Bowen, and Lee Anne Willson. "NLTE Synthetic Spectra of Mira-Type Variable Stars." International Astronomical Union Colloquium 139 (1993): 207. http://dx.doi.org/10.1017/s025292110011735x.

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AbstractWe present NLTE radiative transfer in hydrodynamic models representative of Mira-type variable stars. Calculations were carried out with the PANDORA code of the Bowen models using a snapshot approximation.

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4

Iwanek, Patryk, Igor Soszyński, Szymon Kozłowski, Radosław Poleski, Paweł Pietrukowicz, Jan Skowron, Marcin Wrona, et al. "The OGLE Collection of Variable Stars: Nearly 66,000 Mira Stars in the Milky Way." Astrophysical Journal Supplement Series 260, no. 2 (June 1, 2022): 46. http://dx.doi.org/10.3847/1538-4365/ac6676.

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Abstract We present a collection of 65,981 Mira-type variable stars found in the Optical Gravitational Lensing Experiment (OGLE) project database. Two-thirds of our sample (40,356 objects) are located in the Galactic bulge fields, whereas 25,625 stars are in the Galactic disk. The vast majority of the collection (47,532 objects) comprises new discoveries. We provide basic observational parameters of the Mira variables: equatorial coordinates, pulsation periods, I-band and V-band mean magnitudes, I-band brightness amplitudes, and identifications in other catalogs of variable stars. We also provide the I-band and V-band time-series photometry collected since 1997 during the OGLE-II, OGLE-III, and OGLE-IV phases. The classical selection process, i.e., being mostly based on the visual inspection of light curves by experienced astronomers, has led to the high purity of the catalog. As a result, this collection can be used as a training set for machine-learning classification algorithms. Using overlapping areas of adjacent OGLE fields, we estimate the completeness of the catalog to be about 96%. We compare and discuss the statistical features of Miras located in different regions of the Milky Way. We show examples of stars that change their type over time, from a semiregular variable to Mira and vice versa. This data set is perfectly suited to studying the three-dimensional structure of the Milky Way, and it may help to explain the puzzle of the X-shaped bulge.

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Esipov, V. F., M. I. Pashchenko, G. M. Rudnitskij, M. V. Kozin, E. E. Lekht, A. E. Nadjip, and S. V. Fomin. "Multiwavelength Studies of Mira Ceti-type Variable Stars." Symposium - International Astronomical Union 191 (1999): 201–6. http://dx.doi.org/10.1017/s0074180900203082.

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Since 1994, observations of a sample of about 20 Mira Ceti-type and semiregular variables have been carried out in three spectral ranges: radio (H2O maser line λ = 1.35 cm), optical (spectroscopy and UBV photometry) and infrared (JHKLM photometry). Time series of the Hα emission intensity and H2O line flux, covering several periods of the stars, have been obtained. Correlation of the intensity variations of the H2O maser with optical variability in the maser stars RR Aql, U Ori, VX Sgr and others was confirmed. One of the most interesting results is the flare of the H2O maser emission in R Leo, which happened in autumn 1997, 14 months after a flare of the Hα emission.

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6

Little, S. J., and I. R. Little-Marenin. "The 8-22μm Excess in Carbon Stars From IRAS LRS Spectra." International Astronomical Union Colloquium 106 (1989): 402. http://dx.doi.org/10.1017/s0252921100063429.

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We have measured the excess IR emission from carbon mira and SR variable stars from IRAS LRS spectra. The 8-22μm excess is defined as the ratio of flux above a 2500K energy distribution fit to the LRS spectrum at about 8μm. The carbon star LRS spectra show both emission and absorption features, which are incorporated into our 8-22pm excess. The most prominent feature in carbon stars is the 11.2μm SiC dust emission feature extending from 10μm to 13.8 μm. We observe another emission feature of unknown origin which peaks between 8.4-8.7μm. The SiC emission feature is occasionally blended on the red side by an absorption feature (attributed to gaseous HCN + C2H2) which extends from about 12-16μm. Many of the spectra appear to turn down at the 8μm end due (?) to an HCN + C2H2 absorption feature located at 7.1μm. Carbon stars do not generally show as large an excess as the M mira variables do. The figure below shows our measured excesses for both carbon miras and carbon semi-regular variables. There appears to be little correlation of excess with period, however the mira variables show about twice the range of variation of excess that the semi-regular variables do. We find little correlation between our measured 8-22μm excess and the excesses of Jura (Ap. J., 303, 327, 1986) based on the ratio of 12μm flux to 2μm flux. Our data do support hi s conclusion that longer period variable stars show larger average excesses, but this is only true for mira variables in our analysis.

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7

Rudnitskij, Georgij M. "Molecular Masers in Variable Stars." Publications of the Astronomical Society of Australia 19, no. 4 (2002): 499–504. http://dx.doi.org/10.1071/as02018.

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AbstractWhen a star with a mass of one to a few solar masses enters the red giant stage of its evolution, the radius of its atmosphere reaches several astronomical units. Pulsational instability is typical for this stage. Most stars become Mira-type or semiregular variables with light cycles of a few hundred days. Red giants lose mass at a rate M = 10−7−10−5M⊙ yr−1. Extensive gas–dust circumstellar envelopes form. These envelopes contain various molecular species. Some of these molecules (OH, H2O, SiO, HCN) manifest themselves in maser radio emission. Data on the H2O maser variability and its connection with the stellar brightness variations are discussed. In the H2O line circumstellar masers can be divided into ‘stable’ (showing persistent emission — R Aql, U Her, S CrB, X Hya) and ‘transient’ (appearing in the H2O line once per 10–15 stellar light cycles — R Leo, R Cas, U Aur). Physical mechanisms of the maser variability are discussed. The most probable process explaining the observed visual–H2O correlation is the influence of shock waves on the masing region. Usually it is assumed that shocks in Mira atmospheres are driven by stellar pulsations. Here an alternative explanation is proposed. If a star during its main sequence life possessed a planetary system, similar to the solar system, the planets will be embedded in a rather dense and hot medium. Effects of a planet revolving around a red giant at a short distance (inside its circumstellar envelope) are discussed. A shock produced by the supersonic motion of a planet can account for the correlated variability of the Hα line emission and H2O maser. If the planetary orbit is highly eccentric, then the connected Hα–H2O flare episodes may be explained by the periastron passage of the planet. New tasks for the upgraded ATCA are discussed.

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8

Mennessier, Marie-Odile, Hichame Boughaleb, and Janet A. Mattei. "Comparison of Mean Light Curve Parameters of M, S and C Mira and Semi-Regular Variable Stars Using 75 Years of AAVSO Data." Symposium - International Astronomical Union 177 (2000): 165–70. http://dx.doi.org/10.1017/s0074180900002370.

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Using 75 years of AAVSO data, mean light curve parameters of a sample of 350 long-period M, S and C Mira and semi-regular variable stars have been investigated. We compare M, S and C Mira and semi-regular stars, present a classification of the light curves of LPVs and give discriminant parameters.

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9

Kudashkina, L. S., and I. L. Andronov. "Multiharmonic analysis of Mira-type stars." Symposium - International Astronomical Union 180 (1997): 353. http://dx.doi.org/10.1017/s0074180900131286.

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The shapes of light curves of Mira-type variable stars are analyzed by using the multi–harmonic fit (Andronov 1994). The light curves of 63 stars best covered by the AAVSO observations and published by Mattei (1978) were used. Some correlations between the characteristics of the mean light curves were found.

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10

Shibahashi, Hiromoto. "Implication of a P-L Relation of Mira Variables." International Astronomical Union Colloquium 139 (1993): 103. http://dx.doi.org/10.1017/s0252921100117014.

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Feast et al. (1989) obtained observationally a period-luminosity (P-L) relation of Mira variables in LMC. Basically, fundamental periods of stellar pulsation should be determined by two quantities —a mass and a radius of the star. The existence of a P-L relation implies a special condition that reduces a function of two variables into a function of only a single variable. Though the AGB appears as a thin line in the HR diagram like the Cepheid instability strip, it is an “asymptotically” merged line of evolutionary tracks of stars in a range of about 0.5-3 solar masses. This fact means that the masses of stars on a point of the AGB are not unique though the radii and the effective temperatures are unique, respectively. Therefore we cannot expect, in the case of AGB stars, that a period is reduced to a function of a single variable.

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11

Yeşilyaprak, C., and Z. Aslan. "Kinematics of M-Type Giant Semi-Regular Variables from the Hipparcos Catalogue." Publications of the Astronomical Society of Australia 25, no. 2 (2008): 63–68. http://dx.doi.org/10.1071/as07015.

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AbstractThe kinematics of M-type (O-rich) giant semi-regular (SR) variable stars were examined. They were grouped with respect to their relative parallax errors (επ/π) in order to study the stars having relatively better parallax, and with the period limit (70 d). The spatial and velocity distributions were examined and the results were compared with the results of irregular (L) and Mira-type variables. It was found that M-type giant SR variables are distributed similarly to thin-disc stars and form a kinematically homogeneous group. When the kinematic properties of M-type giant SR variables were compared with those of L- and Mira-type variables, it was estimated that M-type giant SR variables behave as old-disc objects and their kinematic ages vary approximately between 2 and 9 Gyr.

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12

Ita, Yoshifusa, Toshihiko Tanabé, Noriyuki Matsunaga, and Yoshikazu Nakada. "Period-K magnitude relations of variable stars in the LMC." International Astronomical Union Colloquium 193 (2004): 50–54. http://dx.doi.org/10.1017/s0252921100010320.

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AbstractWe cross-correlated the OGLE-II database with the SIRIUS JHK survey data in the Large Magellanic Cloud (LMC). After eliminating obvious spurious variables, we determined the pulsation periods for 9 681 stars by applying the Phase Dispersion Minimization (PDM) technique to the OGLE-II data. Based on these data, we studied the period-K magnitude (PK) relations of variable stars in the LMC and found a new sequence. Comparison between the theoretical pulsation model (Wood & Sebo 1996) and observational data suggests that the variable stars on the new sequence are Mira variables pulsating in the first overtone mode.

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13

Crowe, Richard A., and Robert F. Garrison. "The visible spectra of Southern Hemisphere Mira variable stars." Astrophysical Journal Supplement Series 66 (February 1988): 69. http://dx.doi.org/10.1086/191247.

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14

Cotton, W. D., B. Mennesson, P. J. Diamond, G. Perrin, V. Coudé du Foresto, G. Chagnon, H. J. van Langevelde, et al. "VLBA observations of SiO masers towards Mira variable stars." Astronomy & Astrophysics 414, no. 1 (January 2004): 275–88. http://dx.doi.org/10.1051/0004-6361:20031597.

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15

Wareing, Christopher John. "Wonderful Mira." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1884 (September 23, 2008): 4429–40. http://dx.doi.org/10.1098/rsta.2008.0167.

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Since being named ‘wonderful’ in the seventeenth century for its peculiar brightness variability, Mira A has been the subject of extensive research and become the prototype for a whole class of ‘Mira’ variable stars. The primary star in a binary system, Mira A is reaching the end of its life and currently undergoing an extended period of enhanced mass loss. Recent observations have revealed a surrounding arc-like structure and a stream of material stretching 12 light years away in opposition to the arc. In this article, I review recent modelling of this cometary appearance as a bow shock with an accompanying tail of material ram pressure stripped from the head of the bow shock, place Mira in an evolutionary context, predict its future with reference to the similar star R Hya and planetary nebula Sh 2-188, and speculate some avenues of research both on Mira itself and on other ‘Mira-like’ stars with bow shocks and tails. I also discuss the implications of this discovery for our own star, the Sun.

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16

Jorissen, A., M. Dedecker, B. Plez, R. Alvarez, D. Gillet, and A. B. Fokin. "Tomography of the Atmosphere of the Mira Variable Z Oph." International Astronomical Union Colloquium 185 (2002): 428–31. http://dx.doi.org/10.1017/s0252921100016729.

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AbstractThe new tomographic technique devised by Alvarez et al. (2000) to explore the velocity field across the atmosphere of long-period variable stars (LPVs) is applied to the Mira variable Z Oph. The method cross-correlates the optical spectrum with numerical masks constructed from synthetic spectra and probing layers of increasing depths. This technique reveals that the line doubling often observed in LPVs around maximum light is the signature of the shock wave propagating in the atmosphere of these pulsating stars.

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17

Iwanek, Patryk, Radosław Poleski, Szymon Kozłowski, Igor Soszyński, Paweł Pietrukowicz, Makiko Ban, Jan Skowron, et al. "A Three-dimensional Map of the Milky Way Using 66,000 Mira Variable Stars." Astrophysical Journal Supplement Series 264, no. 1 (January 1, 2023): 20. http://dx.doi.org/10.3847/1538-4365/acad7a.

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Abstract We study the three-dimensional structure of the Milky Way using 65,981 Mira variable stars discovered by the Optical Gravitational Lensing Experiment survey. The spatial distribution of the Mira stars is analyzed with a model containing three barred components that include the X-shaped boxy component in the Galactic center (GC) and an axisymmetric disk. We take into account the distance uncertainties by implementing the Bayesian hierarchical inference method. The distance to the GC is R 0 = 7.66 ± 0.01(stat.) ± 0.39(sys.) kpc, while the inclination of the major axis of the bulge to the Sun–GC line of sight is θ = 20.°2 ± 0.°6(stat.) ± 0.°7(sys.). We present, for the first time, a detailed three-dimensional map of the Milky Way composed of young and intermediate-age stellar populations. Our analysis provides independent evidence for both the X-shaped bulge component and the flaring disk (being plausibly warped). We provide the complete data set of properties of Miras that were used for calculations in this work. The table includes mean brightness and amplitudes in nine photometric bands (covering a range of wavelengths from 0.5 to 12 μm), photometric chemical type, estimated extinction, and calculated distance with its uncertainty for each Mira variable. The median distance accuracy to a Mira star is at the level of 6.6%.

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18

Pijpers, Frank P. "Radial Pulsation in Variable Stars with Mass Loss." International Astronomical Union Colloquium 137 (1993): 575–77. http://dx.doi.org/10.1017/s0252921100018492.

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AbstractIt is possible to show that cool giants with very large photospheric scale heights do not perfectly reflect pulsational waves at the photosphere. This means that for these stars the classical formulation of pulsation in which the outer boundary for the resonance cavity is assumed to be perfectly reflecting is not valid. This can have significant consequences for the eigenfrequencies of the pulsation of Long Period Variables such as Mira type variables as well as for the stability of their pulsation.

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Arnold, R. A., M. Virginia McSwain, Joshua Pepper, and Keivan G. Stassun. "Observational Properties of Miras in the KELT Survey." Proceedings of the International Astronomical Union 14, S343 (August 2018): 349–50. http://dx.doi.org/10.1017/s1743921319002291.

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AbstractWe present a catalog of the observed properties of Mira-type variable stars detected with the Kilodegree Extremely Little Telescope (KELT). Asymptotic giant branch (AGB) candidates were identified in KELT using a combination of photometric data from KELT and 2MASS colors. Of the 4 million objects with KELT photometry, 3332 Mira-like variables were identified. Here, we present their observed periods and luminosities which will place important constraints on future theoretical work on the effect convection has on pulsation periods and mode stability.

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Bessell, M. S., and M. Scholz. "Photospheric Models for Cool Giant Stars." International Astronomical Union Colloquium 106 (1989): 67–80. http://dx.doi.org/10.1017/s0252921100062734.

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AbstractModels for M and C giant stars differ from those for hotter stars by having complicated state equations and opacities dominated by lines from diatomic and polyatomic molecules. In addition many cool giants have atmospheres which are extended, and which cannot therefore be adequately modelled using a plane-parallel approximation. Mira variable stars have atmospheres which are even more extended due to the regular passage of shock waves through their atmosphere. In this review we will discuss recent modelling of such atmospheres and show comparisons with observations of variable and non-variable M stars.

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Hinzel, David H. "Light Curve Analysis of Nine Algol (EA) Eclipsing Binaries Discovered During the Dauban Survey." Research Notes of the AAS 6, no. 11 (November 4, 2022): 231. http://dx.doi.org/10.3847/2515-5172/ac9d9e.

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Abstract The Dauban Survey was a project focused on photometric observations in the Milky Way. This project was a collaboration between Francois Kugel and Jerome Caron utilizing the Observatoire de Chante-Perdix Dauban (MPC A77) in France between 2012 September 17 and 2014 July 20. Over this period, a total of 7826 known variable stars and 5521 new, unknown variable stars were detected. In particular, 497 new variables were published in the AAVSO VSX database. These included Mira Ceti, cataclysmic variables, RR Lyrae, cepheids, and nine EA eclipsing systems. It is the nine EA eclipsing binaries that are the focus of this research.

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22

van Belle, G. T., H. M. Dyck, J. A. Benson, and M. G. Lacasse. "Angular Size Measurements of 18 Mira Variable Stars at 2.2 (?)." Astronomical Journal 112 (November 1996): 2147. http://dx.doi.org/10.1086/118170.

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Dickinson, D. F., B. E. Turner, P. R. Jewell, and P. J. Benson. "OH masers in short-period Mira and semiregular variable stars." Astronomical Journal 92 (September 1986): 627. http://dx.doi.org/10.1086/114193.

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Cotton, W. D., W. Vlemmings, B. Mennesson, G. Perrin, V. Coudé du Foresto, G. Chagnon, P. J. Diamond, et al. "Further VLBA observations of SiO masers toward Mira variable stars." Astronomy & Astrophysics 456, no. 1 (August 23, 2006): 339–50. http://dx.doi.org/10.1051/0004-6361:20065134.

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Yanagita, T., H. Satoh, and K. Saijo. "Chaotic Behavior and Statistical Analysis of Some Mira and Sr Stars." International Astronomical Union Colloquium 134 (1993): 149–51. http://dx.doi.org/10.1017/s0252921100014068.

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26

Neilson, Hilding R., Richard Ignace, and Gary D. Henson. "Long-term polarization observations of Mira variable stars suggest asymmetric structures." Proceedings of the International Astronomical Union 9, S301 (August 2013): 463–64. http://dx.doi.org/10.1017/s1743921313015068.

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AbstractMira and semi-regular variable stars have been studied for centuries but continue to be enigmatic. One unsolved mystery is the presence of polarization from these stars. In particular, we present 40 years of polarization measurements for the prototype o Ceti and V CVn and find very different phenomena for each star. The polarization fraction and position angle for Mira is found to be small and highly variable. On the other hand, the polarization fraction for V CVn is large and variable, from 2–7%, and its position angle is approximately constant, suggesting a long-term asymmetric structure. We suggest a number of potential scenarios to explain these observations.

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27

van Belle, G. T., R. R. Thompson, and M. J. Creech-Eakman. "Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II." Astronomical Journal 124, no. 3 (September 2002): 1706–15. http://dx.doi.org/10.1086/342282.

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Engels, D., A. Winnberg, J. Brand, and F. Jiménez-Esteban. "Variability of masers in circumstellar shells on timescales of decades." Proceedings of the International Astronomical Union 3, S242 (March 2007): 318–19. http://dx.doi.org/10.1017/s174392130701321x.

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AbstractBased on a 15–20 year long monitoring program of H2O masers and new observations of OH masers discovered 35 years ago, we studied the variability of maser emission in AGB stars over timescales of decades. The H2O maser features in the semi-regular variable stars RX Boo and SV Peg, and of the Mira stars U Her and R Cas, showed strong fluctuations superposed in case of the Mira stars on regular variations due to the pulsation of the stars. The spatial distribution of the emission regions in RX Boo and U Her showed deviations from spherical symmetry, which remained unchanged over >10 years. We conclude that the spatial asymmetry is determined by the underlying asymmetry of the mass loss process. There is no evidence that mass loss rates or the wind geometry in these stars have varied over the last 20 years. In 2005 we re-detected at 1612 MHz the 114 OH/IR stars discovered before 1978, implying an OH maser lifetime of >2800 years (1σ).

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Goupil, M. J., A. Baglin, and M. Auvergne. "Period Doubling in Variable Stars: A Tentative Interpretation of Oberved Light Curves of Variable White Dwarfs and Mira Stars." International Astronomical Union Colloquium 111 (1989): 268. http://dx.doi.org/10.1017/s0252921100011763.

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AbstractIrregular pulsations are commonly observed in many groups of pulsating stars. An interpretation in terms of superposition of modes of pulsation is sometimes barely convincing when too many modes have to be considered and when unexpected ratios of frequenceis are observed.

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Andronov, I. L., L. S. Kudashkina, and G. M. Rudnitskij. "Investigation of a Sample of Long-Period Variable Stars Possessing Maser Emission." International Astronomical Union Colloquium 106 (1989): 298. http://dx.doi.org/10.1017/s025292110006317x.

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An investigation of parameters of a sample of more than two hundred late-type long-period variable stars (LPVs) has been carried out. In more detail were studied 13 giants (Mira Ceti-type variables R Aql, RR Aql, RT Aql, R Leo, U Ori, U Her, R Cas, R Tau, Z Cyg, R Peg, U Aur and semiregular variables RT Vir and RX Boo) and 2 supergiants (S Per, PZ Cas). A considerable fraction of the sample stars (about one third) possess circumstellar maser emission in molecular spectral lines (OH, H20, SiO). Our aim was to elucidate the particularities of photometric characteristics of maser stars, such as period P, amplitude A, light curve asymmetry f = (M-m)/P, and, in prospect, to determine their status in course of their evolution on the asymptotic giant branch. An extensive comparison with non-maser LPVs was made.

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Glass, I. S., S. Matsumoto, B. S. Carter, and K. Sekiguchi. "Interesting Variables near the Quintuplet Cluster." Symposium - International Astronomical Union 192 (1999): 81–84. http://dx.doi.org/10.1017/s0074180900203938.

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Two of the five cocoon stars in the “Quintuplet” cluster of young, luminous objects, located about 30 pc in projection from the Galactic Centre, are variables. The nearby “Pistol Star”, also called the “Serendipitous Star”, and a similar object, both suspected on spectroscopic grounds of being Luminous Blue Variables, have indeed been found to vary, confirming their tentative classification. A further variable apparent member of the cluster is probably a Mira in the same line of sight.

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Mikołajewska, Joanna. "Optical and Near-IR Monitoring of Symbiotic Binary Systems." International Astronomical Union Colloquium 183 (2001): 167–76. http://dx.doi.org/10.1017/s0252921100078805.

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AbstractSymbiotic stars are long-period interacting binary systems in which an evolved red giant star transfers material to its much hotter compact companion. Such a composition places them among the most variable stars. In addition to periodic variations due to the binary motion, they often show irregular changes due to nova-like eruptions of the hot component. In some systems the cool giant is a pulsating Mira-type star usually surrounded by a variable dust shell. Here, I present results of optical and IR monitoring of symbiotic systems as well as future prospects for such studies.

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Wood, P. R., C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, et al. "MACHO observations of LMC red giants: Mira and semi-regular pulsators, and contact and semi-detached binaries." Symposium - International Astronomical Union 191 (1999): 151–58. http://dx.doi.org/10.1017/s007418090020301x.

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The MACHO data base has been used to examine light curves of all red giant stars brighter than Mbol ∼ −2 in a 0.5° × 0.5° area of the LMC bar. Periods, often multiple, have been searched for in all stars found to be variable. Five distinct period-luminosity sequences have been found on the low mass (M ≲ 2.25M⊙) giant branch. Comparison of observed periods, luminosities and period ratios with theoretical models identifies Miras unambiguously as radial fundamental mode pulsators, while semi-regular variables can be pulsating in the 1st, 2nd or 3rd overtone, or even the fundamental. All these variables lie on just 3 of the 5 distinct sequences, and they all appear to be on the AGB.The fourth sequence contains red giants on the first giant branch (FGB) or at the red end of the core-helium burning loops of intermediate mass stars (M ≳ 2.25M⊙). The light curves of these stars strongly suggest that they are contact binaries, and they make up ∼0.5% of stars within 1 mag. of the FGB tip. Stars on the fifth sequence show semi-regular, eclipse-like light curves. The light curves and periods of these stars suggest that they are in semi-detached binaries, transfering mass to an invisible companion via a stellar wind or Roche lobe overflow. They make up ∼25% of AGB stars. If the existence of these red giant contact and semi-detached binaries is confirmed, then extant theories of binary star evolution will require substantial modification.

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Smith, Beverly J., David Leisawitz, Michael W. Castelaz, and Donald Luttermoser. "Infrared Light Curves of Mira Variable Stars from [ITAL]COBE[/ITAL] DIRBE Data." Astronomical Journal 123, no. 2 (February 2002): 948–64. http://dx.doi.org/10.1086/338647.

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Sakamoto, Tsuyoshi, Noriyuki Matsunaga, Takashi Hasegawa, and Yoshikazu Nakada. "DISCOVERY OF MIRA VARIABLE STARS IN THE METAL-POOR SEXTANS DWARF SPHEROIDAL GALAXY." Astrophysical Journal 761, no. 1 (November 21, 2012): L10. http://dx.doi.org/10.1088/2041-8205/761/1/l10.

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36

Brand, Jan, Lara Baldacci, and Dieter Engels. "A study of the H2O maser emission from R Cas." Symposium - International Astronomical Union 206 (2002): 310–13. http://dx.doi.org/10.1017/s0074180900222602.

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Over the past decade we observed a sample of late-type stars (supergiants, semi-regular variables, OH/IR stars, and Mira's) 3-4 times per year in the 1.3-cm line of H2O. The observations were carried out with the Medicina 32-m and the Effelsberg 100-m telescopes. In addition, a sub-sample of these stars was observed at several epochs with the VLA. In our analysis we also use data from the literature, for instance on mass loss and optical variability. The aim is to investigate the properties of the circumstellar outflows and to elucidate the maser-pumping mechanism. In the conference poster we presented some preliminary results of a 4-star sub-set of the data base; in the small space available here, we briefly describe the monitoring program, and discuss the Mira-variable R Cas in some detail.

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Schmid, H. M., and H. Nussbaumer. "Elemental Abundances in Symbiotic Stars." Symposium - International Astronomical Union 155 (1993): 402. http://dx.doi.org/10.1017/s0074180900171918.

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Symbiotic objects are related to planetary nebulae in that they represent late stages of stellar evolution. They are interacting binary systems where a hot companion star ionizes the stellar wind of a red giant. This configuration offers the unique possibility for deriving elemental abundances for cool giants from a nebular spectrum with the diagnostic tools employed for HII regions. The analysis can be applied to different types of symbiotic systems having a G, K or M giant, a Mira variable or a carbon star as cool component. The great advantage of this technique is, that it does not depend on stellar parameters or molecular data, and that it can therefore be used as a test or an alternative for the traditional photospheric abundance determinations.

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Little-Marenin, Irene R. "The Role of Technetium in the Evolution of Red Giants." International Astronomical Union Colloquium 106 (1989): 131–43. http://dx.doi.org/10.1017/s025292110006276x.

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AbstractTc is detected in many AGB stars providing unambiguous proof that recent nuclear s-processing and mixing (the third dredge-up) has taken place. During this evolutionary episode the atmospheres of AGB stars are progressively enhanced with helium burning products (primari ly l2C) and s-process elements as they evolve from M->MS->S->SC->C stars. The increase in s-process elements can be traced most easily by the presence and increasing strength of the Tc I lines accompanying this progression. We also find that the third dredge-up phase is accompanied by an increase in the amplitude of light variation since no non-variable or low amplitude variable M, MS, SC, or S (with one exception) have Tc lines. M star Mira variables show Tc if P > 300d (low mass Pop I stars). No Pop II star is known to have Tc. Nor do supergiants show Tc I lines. The significant fraction of MS, S and C stars that do not show Tc, are surmised to be cooler analogues to the Ba II stars, i.e. binaries. The source to provide the neutrons for the s-process is most likely the 13C(a, n)16O reaction since most of the stars in which we observe Tc are thought to have masses less than 3 solar masses.

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Wing, Robert F. "The Distances and Absolute Magnitudes of Some Well-Known Red Variables." Highlights of Astronomy 11, no. 1 (1998): 567. http://dx.doi.org/10.1017/s1539299600022243.

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Distances and absolute magnitudes have been obtained from an early distribution of Hipparcos data for a number of well-known late-type variables. These data were requested in 1981 in order to ensure that these important stars were not excluded from the Input Catalogue on account of their variability or very red color.Measurements were requested for 20 Mira variables, and 14 of these were successfully observed. Of these, the nearest to the Sun were found to be R Leo (at 102 pc), χ Cyg (106), R Cas (107), R Car (128), T Cep (210),and R Aql (211), with formal errors ranging from ±12 to ±57 pc. Mira itself was not considered because the presence of a companion causes an 11-month wobble in its photocenter which is likely to lead to a spurious parallax. The absolute visual magnitudes of Miras at mean maximum range approximately from -2.5 to +2.0 with a clear dependence on spectral type (cooler stars being fainter). This trend is reversed for absolute magnitudes in the near infrared.Results are also given for 10 small-amplitude variables of late type. The nearest of these are L2 Pup (M5 III, 61 pc) and R Dor (M8e, 62pc). The symbiotic star CH Cyg lies at a rather uncertain distance of 268 ± 65 pc.Data were obtained for 23 carbon stars, including the brightest representatives of each of several subgroups. The nearest of these was found to be the SRb variable U Hya, at 162 ± 20 pc. The stars 19 Psc, Y CVn, W Ori, and HD 201626 were all found to be somewhat more than 200 pc away.

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Groenewegen, Martin A. T. "Variable stars in the Gaia era: Mira, RR Lyrae, δ and Type-II Cepheids." Proceedings of the International Astronomical Union 12, S330 (April 2017): 287–96. http://dx.doi.org/10.1017/s1743921317005506.

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AbstractClassical variables like RR Lyrae, classical and Type-II Cepheids and Mira variables all follow period-luminosity relations that make them interesting as distance indicators. Especially the RR Lyrae and δ Cepheids are crucial in establishing the distance scale in the Universe, and all classes of variables can be used as tracers of galactic structure. I will present an overview of recent period-luminosity relations and review the work that has been done using the Gaia DR1 data so far, and discuss possibilities for the future.

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Cho, Se-Hyung. "Observations of SiO J=2–1 and J=3–2 masers towards evolved stars with the TRAO 14 m telescope." Proceedings of the International Astronomical Union 3, S242 (March 2007): 314–15. http://dx.doi.org/10.1017/s1743921307013191.

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AbstractWe present the results of survey and time-monitoring observations of SiO J=2–1 and J=3–2 masers towards evolved stars with the 14 m radio telescope at Taeduk Radio Astronomy Observatory (TRAO) from 1995 February to 2001 February. The first detection of SiO v=3, J=2–1 maser emission toward S-type Mira variable χ Cyg is also presented.

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Wood, P. R. "Variable Red Giants in the LMC: Pulsating Stars and Binaries?" Publications of the Astronomical Society of Australia 17, no. 1 (2000): 18–21. http://dx.doi.org/10.1071/as00018.

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AbstractInfrared J and K photometry has been obtained of all red giants in the half square degree region of the LMC bar searched for variables using the MACHO database byWood et al. (1999). The K–log P diagram shows the five distinct period–luminositysequences which are also evident in the MACHO photometry. The K–log P plot allowsidentification of the Mira sequence from among the five observed sequences. As shown in Wood et al. (1999), comparison of observed periods, luminosities and period ratios with theoretical models identifies Miras unambiguously as radial fundamental mode pulsators, while semi-regular variables can be pulsating in the first, second or third overtone, or even the fundamental mode. All these variables lie on just three of the five distinct sequences, and they all appear to be on the AGB. The nature of the variability of stars on the other two sequences is currently unknown. Possibilities include contact and semi-detached binaries, rotating stars with giant star spots, episodic dust formation, rotationally stabilised non-radial g− modes and strange pulsation modes caused by convection–pulsation interaction. These possibilities are discussed.

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Yao, Yuhan, Chao Liu, Licai Deng, Richard de Grijs, and Noriyuki Matsunaga. "Mira Variable Stars from LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection." Astrophysical Journal Supplement Series 232, no. 1 (September 22, 2017): 16. http://dx.doi.org/10.3847/1538-4365/aa88a9.

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Szymczak, M., and A. M. Le Squeren. "A comparison of OH and H2O maser properties of Mira and semiregular variable stars." Monthly Notices of the Royal Astronomical Society 304, no. 2 (April 7, 1999): 415–20. http://dx.doi.org/10.1046/j.1365-8711.1999.02321.x.

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45

Allen, David, and Alan Wright. "A Model for RX Puppis." International Astronomical Union Colloquium 103 (1988): 249–50. http://dx.doi.org/10.1017/s0252921100103549.

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The dust-rich (D-type) symbiotic stars appear always to comprise a mira variable and a star of temperature ∼ 105 K which ionizes the mira’s circumstellar envelope. On timescales of decades they change little, save for the slow pulsation of the mira at infrared wavelengths. RX Puppis is a striking exception to this generalization, however, since it undergoes extraordinary changes.RX Pup drifts between two extremes, exhibiting intermediate states. Table I summarises the known characteristics in the extreme states. Because of its variability, models of RX Pup are more highly constrained, giving us a chance to understand one of the D-type symbiotics.Optical spectra of RX Pup from the Anglo-Australian Telescope. Tie breadth of the lines in 1976 may be due to lower spectral resolution.

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46

Liljeström, Tarja, Anders Winnberg, and Roy Booth. "New detections of 321 GHz water masers toward late-type stars." Symposium - International Astronomical Union 206 (2002): 314–17. http://dx.doi.org/10.1017/s0074180900222614.

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The SEST telescope has been used for a submillimeter water maser survey toward late-type stars. Six new 321 GHz water masers were detected. These, as well as the earlier reported sources, VY CMa and o Cet, were also observed in the vibrationally excited water maser line at 96 GHz. However, only VY CMa and o Cet showed the 96 GHz emission. The line velocity of o Cet is blueshifted, suggesting that the hot water vapor at 96 GHz takes part in the pulsation-shock motion of the Mira variable.

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Nikzat, F., C. E. Ferreira Lopes, M. Catelan, R. Contreras Ramos, M. Zoccali, A. Rojas-Arriagada, V. F. Braga, D. Minniti, J. Borissova, and I. Becker. "The VVV survey: Long-period variable stars." Astronomy & Astrophysics 660 (April 2022): A35. http://dx.doi.org/10.1051/0004-6361/202141805.

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Context. Long-period variable stars (LPVs) are pulsating red giants, primarily in the asymptotic giant branch phase, and they include both Miras and semi-regular variables (SRVs). Their period-age and period-luminosity relations enable us to trace different stellar populations, as they are intrinsically very bright and cover a wide range in distances and ages. Aims. The purpose of this study is to establish a census of LPV stars in a region close to the Galactic center, using the six-year database of the Vista Variables in the Vía Láctea (VVV) ESO Public Survey, as well as to describe the methodology that was employed to search for and characterize LPVs using VVV data. Near-IR surveys such as VVV provide a unique opportunity to probe the high-extinction innermost regions of the Milky Way. The detection and analysis of the intrinsically bright Miras in this region could provide us with an excellent probe of the properties of the Milky Way far behind its bulge. Methods. We used point-spread function photometry for all available Ks-band images in ten VVV tiles, covering 16.4 deg2 in total, overlapping fields observed in the course of the Optical Gravitational Lensing Experiment (OGLE)-III survey. We designed a method to select LPV candidates, and we used the known variables from OGLE-III and other known variables from the literature to test our approach. The reduced χ2 statistic, along with the flux-independent index K(fi), were used in our analysis. The Lomb-Scargle period search method, Fourier analysis, template fitting, and visual inspection were then performed to refine our sample and characterize the properties of the stars included in our catalog. Results. A final sample of 130 Mira candidates, of which 129 are new discoveries, was thus obtained, with periods in the range between about 80 and 1400 days. Moreover, a sample of 1013 LPV candidates is also presented, whose periods are however not sufficiently constrained by the available data. A fraction of the latter may eventually turn out to be SRVs. Ages are measured for these stars based on a reassessment of the period-age relations available in the literature. The Miras in our catalog include 18 stars satisfying the requirements to serve as reliable distance indicators and which are not saturated in the VVV Ks-band images. Their distances are accordingly derived and discussed. A number of objects that are seemingly placed far behind the Milky Way’s bulge was detected.

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Cunha, M. S., P. P. Avelino, and W. J. Chaplin. "From solar-like to mira stars: a unifying description of stellar pulsators in the presence of stochastic noise." Monthly Notices of the Royal Astronomical Society 499, no. 4 (September 25, 2020): 4687–97. http://dx.doi.org/10.1093/mnras/staa2932.

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ABSTRACT We discuss and characterize the power spectral density properties of a model aimed at describing pulsations in stars from the main-sequence to the asymptotic giant branch. We show that the predicted limit of the power spectral density for a pulsation mode in the presence of stochastic noise is always well approximated by a Lorentzian function. While in stars predominantly stochastically driven the width of the Lorentzian is defined by the mode lifetime, in stars where the driving is predominately coherent the width is defined by the amplitude of the stochastic perturbations. In stars where both drivings are comparable, the width is defined by both these parameters and is smaller than that expected from pure stochastic driving. We illustrate our model through numerical simulations and propose a well-defined classification of stars into predominantly stochastic (solar-like) and predominately coherent (classic) pulsators. We apply the model to the study of the Mira variable U Per, and the semiregular variable L2 Pup and, following our classification, conclude that they are both classical pulsators. Our model provides a natural explanation for the change in behaviour of the pulsation amplitude-period relation noted in several earlier works. Moreover, our study of L2 Pup enables us to test the scaling relation between the mode line width and effective temperature, confirming that an exponential scaling reproduces well the data all the way from the main sequence to the asymptotic giant branch, down to temperatures about 1000 K below what has been tested in previous studies.

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Shinnaga, Hiroko, Masato Tsuboi, and Takashi Kasuga. "Highly polarized SiO v = 0 emission from late-type stars." Symposium - International Astronomical Union 206 (2002): 278–81. http://dx.doi.org/10.1017/s0074180900222535.

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We briefly report the results of polarimetric observations of SiO emission from late-type stars taken with a millimeter polarimeter installed at the Nobeyama 45m telescope. We found that the SiO J = 2 − 1 emission in the v = 0 state from R Cas contains a highly linearly polarized component, followed by the detection of highly linearly polarized emission of the same transition from VY CMa (Shinnaga et al. 1999). The high polarization degree is a strong evidence that the v = 0 emission originates from maser action. We found out that, not only a peculiar supergiant star, but also a Mira variable star is associated with the SiO v = 0 maser.

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Chen, Pei-Sheng, Xiao-Hong Yang, Hong-Guang Shan, and Pin Zhang. "Infrared spectral variations of three Mira variable carbon stars with the 11.3 μm SiC feature." Astrophysics and Space Science 319, no. 2-4 (December 9, 2008): 93–99. http://dx.doi.org/10.1007/s10509-008-9956-7.

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