Asymptotic Giant Branch Mass Loss Research Articles

Spatially resolving the AGB star V3 in the metal-poor globular cluster 47 Tuc with VLTI/GRAVITY

Context. Mass loss at the asymptotic giant branch (AGB) plays an important role not only in the final fates of stars, but also in the chemical evolution of galaxies. Nevertheless, the metallicity effects on AGB mass loss are not yet fully understood. Aims. We present spatially resolved observations of an AGB star, V3, in the metal-poor globular cluster 47 Tuc (NGC 104). Methods. The AGB star 47 Tuc V3 was observed using the GRAVITY instrument at ESO’s Very Large Telescope Interferometer (VLTI) at 2–2.45 μm, with a projected baseline length of up to 96 m. Results. The object 47 Tuc V3 has been spatially resolved and stands as the first to attempt to spatially resolve an individual star in a globular cluster. The uniform-disk fit to the observed data results in an angular diameter of ∼0.7 mas. Our modeling of the spectral energy distribution and near-infrared interferometric GRAVITY data suggests that the observed data can be explained by an optically thin dust shell with a 0.55 μm optical depth of 0.05–0.25, consisting of metallic iron grains, likely together with effects of the extended atmosphere of the central star. The dust temperature at the inner shell boundary is 500–800 K (corresponding to 23–90 stellar radii), significantly lower than observed in nearby oxygen-rich AGB stars. Radiation pressure on small (< 0.05 μm) iron grains is not sufficient to drive stellar winds. Therefore, iron grains may grow to larger sizes, even in the metal-poor environment. Alternatively, it is possible that the observed iron grain formation is a result of the mass outflow initiated by some other mechanism(s). Conclusions. The sensitivity and angular resolution of VLTI provides a new window onto spatially resolving individual stars in metal-poor globular clusters. This allows us to improve subsequent studies of the metallicity dependence of dust formation and mass loss.

Mass Loss in Evolved Stars

AbstractIntense mass loss through cool, low-velocity winds is a defining characteristic of low-to-intermediate mass stars during the asymptotic giant branch (AGB) evolutionary stage. Such winds return up ∼80% of the initial stellar mass to the interstellar medium and play a major role in enriching it with dust and heavy elements. A challenge to understanding the physics underlying AGB mass loss is its dependence on an interplay between complex and highly dynamic processes, including pulsations, convective flows, shocks, magnetic fields, and opacity changes resulting from dust and molecule formation. I highlight some examples of recent advances in our understanding of late-stage stellar mass loss that are emerging from radio and (sub)millimeter observations, with a particular focus on those that resolve the surfaces and extended atmospheres of evolved stars in space, time, and frequency.

Pulsation-triggered dust production by asymptotic giant branch stars

Eleven nearby (<300 pc), short-period (50-130 days) asymptotic giant branch (AGB) stars were observed in the CO J = (2-1) line. Detections were made towards objects that have evidence for dust production (Ks-[22] >~ 0.55 mag; AK Hya, V744 Cen, RU Crt, alpha Her). Stars below this limit were not detected (BQ Gem, eps Oct, NU Pav, II Hya, CL Hyi, ET Vir, SX Pav). Ks-[22] colour is found to trace mass-loss rate to well within an order of magnitude. This confirms existing results, indicating a factor of 100 increase in AGB-star mass-loss rates at a pulsation period of ~60 days, similar to the known "superwind" trigger at ~300 days. Between ~60 and ~300 days, an approximately constant mass-loss rate and wind velocity of ~3.7 x 10^-7 solar masses per year and ~8 km/s is found. While this has not been corrected for observational biases, this rapid increase in mass-loss rate suggests a need to recalibrate the treatment of AGB mass loss in stellar evolution models. The comparative lack of correlation between mass-loss rate and luminosity (for L <~ 6300 solar luminosities) suggests that the mass-loss rates of low-luminosity AGB-star winds are set predominantly by pulsations, not radiation pressure on dust, which sets only the outflow velocity. We predict that mass-loss rates from low-luminosity AGB stars, which exhibit optically thin winds, should be largely independent of metallicity, but may be strongly dependent on stellar mass.

Challenges of AGB modelling with dust

AbstractWe report on the most recent progresses on the modelling of the asymptotic giant branch (AGB) phase. We show that dust formation in the wind of AGBs is sensitive to the mass of the precursor, low–mass AGB with mass below ~ 3 M⊙ producing mainly carbonaceous dust, whereas their counterparts of higher mass produce silicates and alumina dust. We discuss the uncertainty of the results, due to the poor knowledge of physical mechanisms highly important for AGB evolution, primarily convection and mass loss. We show how the chemical composition of planetary nebulae can be used to draw information on the main features of AGB evolution.

IS THERE A METALLICITY CEILING TO FORM CARBON STARS?—A NOVEL TECHNIQUE REVEALS A SCARCITY OF C STARS IN THE INNER M31 DISK

We use medium-band near-infrared (NIR) Hubble Space Telescope WFC3 photometry with model NIR spectra of Asymptotic Giant Branch (AGB) stars to develop a new tool for efficiently distinguishing carbon-rich (C-type) AGB stars from oxygen-rich (M-type) AGB stars in galaxies at the edge of and outside the Local Group. We present the results of a test of this method on a region of the inner disk of M31, where we find a surprising lack of C stars, contrary to the findings of previous C star searches in other regions of M31. We find only 1 candidate C star (plus up to 6 additional, less certain C stars candidates), resulting in an extremely low ratio of C to M stars (C/M = (3.3(+20,-0.1))x10^-4) that is 1-2 orders of magnitude lower than other C/M estimates in M31. The low C/M ratio is likely due to the high metallicity in this region which impedes stars from achieving C/O > 1 in their atmospheres. These observations provide stringent constraints evolutionary models of metal-rich AGB stars and suggest that there is a metallicity threshold above which M stars are unable to make the transition to C stars, dramatically affecting AGB mass loss and dust production and, consequently, the observed global properties of metal-rich galaxies.

Dust production and mass loss in cool evolved stars

AbstractFollowing the red giant branch phase and the subsequent core He‐burning phase, the low‐ to intermediate‐mass stars (0.8 &lt; M /M⊙ &lt; 8) begin to ascend the asymptotic giant branch (AGB). Pulsations levitate material from the stellar surface and provide density enhancements and shocks, which can encourage dust formation and re‐processing. The dust composition depends on the atmospheric chemistry (abundance of carbon relative to oxygen), which is altered by dredging up newly formed carbon to the surface of the star. I will briefly review the current status of models that include AGB mass loss and relate them to recent observations of AGB stars from the Surveying the Agents of Galaxy Evolution (SAGE) Spitzer surveys of the Small and Large Magellanic Clouds, including measures of the total dust input to the interstellar medium from AGB stars. (© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

A giant dusty bipolar structure around the planetary nebula NGC 1514

The transition from spherically symmetric asymptotic giant branch mass loss to aspherical planetary nebulae is an intriguing problem of stellar astrophysics. On 12 μm maps of the Infrared Astronomical Satellite (IRAS), we detected a huge (2.6 pc) dust emission region around the evolved planetary nebula NGC 1514. On 100 and 60 μm IRAS maps, we additionally found two giant (2.1 and 0.9 pc) bipolar dust emission structures centred on NGC 1514; we suspect that each of these regions is physically connected to the planetary nebula. The bipolar structures are slightly tilted with respect to each other, possibly due to precession. The total mass (dust + gas) of all structures is 2.2 ± 1.4 M ⊙ . We argue that NGC 1514 and its dusty surroundings represent one of the very few known cases where the preserved history of all main mass-loss phases of a star of intermediate initial mass can be seen.

THE MASS LOSS RETURN FROM EVOLVED STARS TO THE LARGE MAGELLANIC CLOUD: EMPIRICAL RELATIONS FOR EXCESS EMISSION AT 8 AND 24 μm

We present empirical relations describing excess emission from evolved stars in the Large Magellanic Cloud (LMC) using data from the Spitzer Space Telescope Surveying the Agents of a Galaxy's Evolution (SAGE) survey which includes the Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 {mu}m and Multiband Imaging Photometer (MIPS) 24, 70, and 160 {mu}m bands. We combine the SAGE data with the Two Micron All Sky Survey (2MASS; J, H, and K {sub s}) and the optical Magellanic Cloud Photometric Survey (MCPS; U, B, V, and I) point source catalogs in order to create complete spectral energy distributions (SEDs) of the asymptotic giant branch (AGB) star candidates in the LMC. AGB star outflows are among the main producers of dust in a galaxy, and this mass loss results in an excess in the fluxes observed in the 8 and 24 {mu}m bands. The aim of this work is to investigate the mass loss return by AGB stars to the interstellar medium of the LMC by studying the dependence of the infrared excess flux on the total luminosity. We identify oxygen-rich, carbon-rich, and extreme AGB star populations in our sample based on their 2MASS and IRAC colors. The SEDs ofmore » oxygen- and carbon-rich AGB stars are compared with appropriate stellar photosphere models to obtain the excess flux in all the IRAC bands and the MIPS 24 {mu}m band. Extreme AGB stars are dominated by circumstellar emission at 8 and 24 {mu}m; thus we approximate their excesses with the flux observed in these bands. We find about 16,000 O-rich, 6300 C-rich, and 1000 extreme sources with reliable 8 {mu}m excesses, and about 4500 O-rich, 5300 C-rich, and 960 extreme sources with reliable 24 {mu}m excesses. The excesses are in the range 0.1 mJy to 5 Jy. The 8 and 24 {mu}m excesses for all three types of AGB candidates show a general increasing trend with luminosity. The color temperature of the circumstellar dust derived from the ratio of the 8 and 24 {mu}m excesses decreases with an increase in excess, while the 24 {mu}m optical depth increases with excess. The extreme AGB candidates are the major contributors to the mass loss, and we estimate the total AGB mass loss return to the LMC to be (5.9-13) x 10{sup -3} M {sub sun} yr{sup -1}.« less

The dust condensation sequence in red supergiant stars

Context. Red supergiant (RSG) stars exhibit significant mass loss by means of a slow, dense wind. They are often considered to be the more massive counterparts of Asymptotic Giant Branch (AGB) stars. While AGB mass loss is related to their strong pulsations, the RSG are often only weakly variable. This raises the question of whether their wind-driving mechanism and the dust composition of the wind are the same. Aims. We study the conditions at the base of the wind by determining the dust composition of a sample of RSG. The dust composition is assumed to be sensitive to the density, temperature, and acceleration at the base of the wind. We compare the derived dust composition with the composition measured in AGB star winds. Methods. We compile a sample of 27 RSG infrared spectra (ISO-SWS) and supplement these with photometric measurements to derive the full spectral energy distribution (SED). These data are modelled using a dust radiative-transfer code, taking into account the optical properties of the relevant candidate materials to search for correlations between mass-loss rate, density at the inner edge of the dust shell, and stellar parameters. Results. We find strong correlations between the dust composition, mass-loss rate, and the stellar luminosity, roughly in agreement with the theoretical dust condensation sequence. We identify the need for a continuous (near-)IR dust opacity and tentatively propose amorphous carbon, and we note significant differences with AGB star winds in terms of the presence of PAHs, absence of “the” 13 μm band, and a lack of strong water bands. Conclusions. Dust condensation in RSG is found to experience a freeze-out process that is similar to that in AGB stars. Together with the positive effect of the stellar luminosity on the mass-loss rate, this suggests that radiation pressure on dust grains is an important ingredient in the driving mechanism. Still, differences with AGB stars are manifold and thus the winds of RSG should be studied individually in further detail.

A Review of AGB Mass Loss Imaging Techniques

AbstractCircumstellar imaging across the electromagnetic spectrum allows us to derive fundamental diagnostics for the physics of mass loss in the Asymptotic Giant Branch (AGB) phase. I review the current status of the field, with particular emphasis on the techniques that provide the strongest constraints for mass-loss modeling efforts.

The trigger of the asymptotic giant branch superwind: the importance of carbon

Abstract The driving mechanism of the asymptotic giant branch (AGB) superwind has become controversial in recent years. The efficacy of dust-driven mass loss has been queried. Spitzer observation of AGB stars in local group galaxies shows the surprising result that at low metallicity, AGB mass loss occurs at low luminosity, possibly lower than in the Galaxy, but only for carbon-rich stars. Oxygen-rich stars in the Galaxy and in lower metallicity galaxies have similar mass-loss rates only at high luminosities. To explain this dichotomy, we propose that the superwind has a dual trigger. The superwind starts either when sufficient excess carbon builds up for efficient formation of carbonaceous dust [which we propose occurs when XCO = (C − O)/O⊙ = 0.1], or when the luminosity reaches a value sufficient for a silicate dust-driven wind (proposed at L = 104Z−4/3 L⊙). We show that this dual trigger fits the current observational constraints: the luminosity at which the superwind begins, and the predominance of carbon superwind star at low metallicity. We use stellar evolution models to check the consistency of our explanations and present detailed predictions of the luminosities at which the superwind is triggered for different metallicities and initial stellar masses.

Hubble Space TelescopeNICMOS Imaging Polarimetry of Proto-Planetary Nebulae: Probing the Dust Shell Structure via Polarized Light

Using NICMOS on the Hubble Space Telescope, we have performed imaging polarimetry of proto–planetary nebulae (PPNs). Our objective is to study the structure of optically thin circumstellar shells of post–asymptotic giant branch (AGB) stars by separating dust-scattered, linearly polarized starlight from unpolarized direct starlight. This unique technique allows us to probe faint reflection nebulae around the bright central star, which can be buried under the point-spread function of the central star in conventional imaging. Our observations and archival search have yielded polarimetric images for five sources: IRAS 07134+1005 (HD 56126), 06530-0213, 04296+3429, (Z)02229+6208, and 16594-4656. These images have revealed the circumstellar dust distribution in unprecedented detail via polarized intensity maps, providing a basis for understanding the three-dimensional structure of these dust shells. We have observationally confirmed the presence of the inner cavity caused by the cessation of AGB mass loss, and the internal shell structures, which are strongly tied to the progenitor star's mass-loss history on the AGB. We have also found that equatorial enhancement in these circumstellar shells comes with various degrees of contrast, suggesting a range of optical depths in these optically thin shells. Our data support the interpretation that the dichotomy of PPN morphologies is due primarily to differences in optical depth and secondarily to the inclination effect. The polarization maps reveal a range of inclination angles for these optically thin reflection nebulae, dispelling the notion that elliptical nebulae are pole-on bipolar nebulae.

Detection of MgNC in CRL 618: Tracing Metal Chemistry with Asymptotic Giant Branch Evolution

The MgNC radical has been detected toward the circumstellar shell of CRL 618, the first metal-bearing molecule (in the chemist's sense) observed in this proto-planetary nebula. Five rotational transitions of this 2Σ species were measured using the Arizona Radio Observatory (ARO) 12 m and IRAM 30 m telescopes, several which clearly display the characteristic spin-rotation structure. Searches for NaCN, NaCl, AlF, and AlCl in CRL 618, in contrast, proved negative. The line profiles of MgNC in this source, measured at the 30 m, were somewhat U-shaped and showed no evidence of high-velocity wings, indicating that this radical arises from the remnant asymptotic giant branch (AGB) wind. The column density of MgNC in CRL 618 is Ntot = 2.4 × 1012 cm-2, corresponding to a fractional abundance, relative to H2, of f ~ 5.3 × 10-9. The upper limits for the sodium and aluminum species are typically f < 10-9 to 10-8. The MgNC abundance in CRL 618 is comparable to those measured in CRL 2688 and IRC +10216; the upper limits for the sodium and aluminum compounds are at least a factor of 10 lower in CRL 618 relative to abundances in IRC +10216, but similar to those in CRL 2688. These data suggest that metal-bearing molecules produced by LTE chemistry (NaCl, AlCl, AlF) are destroyed by the events associated with the second stage of AGB mass loss, while radicals such as MgNC survive in the outer envelope for a significant time in the proto-planetary nebula phase.

The post-AGB evolution of AGB mass loss variations

We present new numerical hydrodynamical modelling of the evolution of Asymptotic Giant Branch (AGB) mass loss fluctuations during the post-AGB/Planetary Nebula phase. These models show that after ionization, the observable effects of the mass loss fluctuations disappear in a few thousand years, consistent with the fact that only few PNe have been found to be surrounded by `rings'. We derive the observational characteristics of these rings, and compare them to reported observations of the rings around NGC 6543, finding a good match of emission properties and line shapes. We predict small variations in the observable electron temperatures.

On Dead OH/IR Stars

Because the net duration of all 1612 MHz emission phases from |b| > 10° OH/IR stars is ~1700 yr, one death, as evidenced by the disappearance of all 1612 MHz masers, should occur in a sample of 170 every 10 yr, on average, if they have only one emission phase. We report here on the reobservation after 12 yr of the 328 OH/IR stars in the Arecibo sky with a peak first-epoch I1612 > 100 mJy. Four of these now have undetectable 1612 MHz masers, while those from a fifth, FV Boo, appear to be in terminal decline. The blue IR colors, 315 day period of FV Boo, and presence of water and SiO masers in several of the newly identified dead OH/IR stars all suggest that these objects are still asymptotic giant branch (AGB) stars rather than proto-planetary nebulae. This conclusion suggests that most oxygen-rich AGB stars pass through the OH/IR star phase more than once. The positions of the dead OH/IR stars on first-epoch plots of I1612 versus S(25) and on plots of the ratio of these quantities versus IR color are entirely normal. However, all of the dead OH/IR stars have small, less than 12 km s-1, expansion velocities, and all but one have blue IR colors. When these criteria are used to further delimit the sample, the five dead OH/IR stars in a sample of 112 imply a mean 1612 MHz emission life te ~ 314 (+387, -97) yr. The short duration of this emission phase is readily understood if oxygen-rich AGB stars toward the end of the AGB pass through a brief OH/IR star phase after a thermal pulse, when, as often happens, they are not bright enough to support heavy mass loss on the luminosity ascent to a thermal pulse. Copious AGB mass loss is thus frequently triggered by events that follow a thermal pulse.

Mid‐Infrared Observation of Mass Loss in Elliptical Galaxies

Early-type galaxies exhibit thermal and molecular resonance emission from dust that is shed and heated through stellar mass loss as a subset of the population moves through the asymptotic giant branch (AGB) phase of evolution. Because this emission can give direct insight into stellar evolution in addition to galactic stellar mass loss and interstellar medium injection rates, we conducted a program to search for this signature emission with CAM on the Infrared Space Observatory. We obtained 6-15 μm imaging observations in six narrow bands for nine elliptical galaxies; every galaxy is detected in every band. For wavelengths shorter than 9 μm, the spectra are well matched by a blackbody originating from the K and M stars that dominate the integrated light of elliptical galaxies. At wavelengths between 9 and 15 μm, however, the galaxies display excess emission relative to the stellar photospheric radiation. Additional data taken with the fine-resolution circular variable filter on one source clearly shows broad emission from 9 to 15 μm, peaking around 10 μm. This result is consistent with the known broad silicate feature at 9.7 μm originating in the circumstellar envelopes of AGB stars. This emission is compared with studies of Galactic and Large Magellanic Cloud AGB stars to derive cumulative mass-loss rates. In general, these mass-loss rates agree with the expected ~0.8 M☉ yr-1 value predicted by stellar evolutionary models. Both the photospheric and circumstellar envelope emission follow a de Vaucouleurs R1/4 law, supporting the conclusion that the mid-infrared excess emission originates in the stellar component of the galaxies and acts as a tracer of AGB mass loss and mass injection into the interstellar medium.

On the Number of Comets around White Dwarf Stars: Orbit Survival During the Late Stages of Stellar Evolution

The accretion of comets onto DA white dwarfs can produce observable metal absorption lines. We show here that comet systems around the progenitor main-sequence star are vulnerable to being lost during asymptotic giant branch mass loss, if the mass loss is sufficiently asymmetric to impart modest linear momentum to the white dwarf. This may have bearing on the frequency of observation of heavy elements in white dwarf stars and on inferences regarding the frequency of comet systems, if the imparted linear velocities of white dwarfs can be estimated.

Binary post-AGB stars

Low and intermediate mass stars leave the Asymptotic Giant Branch (AGB) when the mass in their H-rich envelope is less than about 0.01 M⊙, and the high mass loss drops several orders of magnitude. The central star rapidly evolves to the left part of the HR diagram along a track of constant luminosity (e.g. Schönberner 1983). In principle the evolution of the central star to higher Teff and the expansion and cooling of the AGB remnant are easy to calculate. In practice several complicating factors arise which make it much more difficult to predict the morphology and properties of post-AGB stars, such as binarity, post-AGB mass loss and aspherical AGB mass loss. Binarity of post-AGB stars affects the morphology of the circumstellar environment, and it affects evolutionary timescales and surface chemical abundances of the components in the system. This review discusses some properties of binary post-AGB stars.

EVOLUTION FROM AGB STAR TO PLANETARY NEBULA

ABSTRACT Stellar evolution through the asymptotic giant branch (AGB) and planetary nebula (PN) phases is examined with particular emphasis on stellar mass loss. The Mount Stromlo Stellar Structure Code has been used to produce 22 stellar evolutionary sequences, complete from the main sequence to the white dwarf regime. The models correspond to initial masses of 0.89, 0.945, 1.0, 1.5, 2.0, 2.5, 3.5, and 5.0 M\\s, and metallicities 0.016, 0.008, 0.004, and 0.001. Mass loss during the AGB phase has been incorporated into the calculations following the empirical relationship between mass loss rate and pulsation period defined by Galactic AGB stars. The calculations show that the overall time-dependent behaviour of the mass loss rate is significantly modulated during any helium shell flash cycle, and that the AGB phase is terminated by severe mass loss over the last 2--3 helium shell flash cycles. The maximum AGB luminosities predicted are in excellent agreement with those observed for Magellanic Cloud AGB stars. The AGB calculations also indicate that one is likely to observe normal M-, S-, or C-type AGB stars with hollow circumstellar shells. Time-dependent hydrodynamic models of the winds around such stars show that circumstellar matter can flow back towards the star during the luminosity dip experienced immediately following a flash event. Multiple shell planetary nebulae (PNe) may also be the result of this type of behaviour, though the hydrodynamic calculations have not been extended this far as yet. In 21 cases, no effort was made to control the phase of the helium shell flash cycle at which the AGB stage was terminated. An additional 5 cases were constructed by varying the AGB mass loss rate by ~10% over the last stages of AGB evolution, thus varying the phase. The fraction of Hydrogen to Helium burning nuclei suggests that ~40% of all nuclei are preferentially burning Helium when they leave the AGB@. Calculations were extended through the PNN regime, incorporating a semi-empirical mass loss rate which was consistent with radiation pressure driven wind theory to within the large scatter of observational mass loss rates. Spectrophotometric observations were obtained in the range 3400--7900A for a total of 80 PNe in the Magellanic Clouds. Subsequent photoionisation modelling will allow these objects to be placed onto a Hertzsprung-Russell (H--R) diagram. From the modelling data already available in the literature for Magellanic Cloud PNe, the majority appear to conform with the properties of He burning PNN tracks. This is in contrast to Galactic PNe which have been assumed to be powered by H burning nuclei.

Long-period variables in the Large Magellanic Cloud. II - Infrared photometry, spectral classification, AGB evolution, and spatial distribution

view Abstract Citations (199) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Long-Period Variables in the Large Magellanic Cloud. II. Infrared Photometric Spectral Classification, AGB Evolution, and Spatial Distribution Hughes, Shaun M. G. ; Wood, Peter R. Abstract Infrared JHK photometry and visual spectra have been obtained for a large sample of long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Various aspects of the asymptotic giant branch (AGB) evolution of LPVs are discussed using these data. The birth/death rate of LPVs of different ages in the LMC is compared with the birth rates of appropriate samples of planetary nebulae, clump stars, Cepheids, and OH/IR stars. It appears that there are much fewer large-amplitude LPVs per unit galactic stellar mass in the LMC than in the Galaxy. We suggest that this may be due to the fact that the evolved intermediate-age AGB stars in the LMC often turn into carbon stars, which tend to have smaller pulsation amplitudes than M stars. There is also a major discrepancy between the number of LPVs in the LMC (and in the Galaxy) and the number predicted by the theories of AGB evolution, pulsation, and mass loss. A distance modulus to the LMC of 18.66 +/- 0.05 is derived by comparing the LMC LPVs with P ~ 200 days with the 47 Tucanae Mira variables in the (K, log P) plane. The (K, log P) relation is also used to examine the tilt of the LMC populations of old and intermediate-age stars. Publication: The Astronomical Journal Pub Date: March 1990 DOI: 10.1086/115374 Bibcode: 1990AJ.....99..784H Keywords: Asymptotic Giant Branch Stars; Infrared Photometry; Magellanic Clouds; Mira Variables; Spatial Distribution; Stellar Evolution; Color-Magnitude Diagram; Density Distribution; Stellar Luminosity; Stellar Mass; Stellar Spectrophotometry; Astrophysics; GALAXIES: MAGELLANIC CLOUDS; STARS: LONG-PERIOD VARIABLES full text sources ADS | data products SIMBAD (546) NED (1) CDS (1) Related Materials (3) Part 1: 1989AJ.....97.1634H Part 3: 1991AJ....101.1304H Part 4: 1995MNRAS.275..331R