Near IR Observations of the Arecibo Sample of OH/IR Stars

Jiménez-Esteban, F. M.; Engels, D.; García-Lario, P.

doi:10.1007/978-94-015-9688-6_7

Cited by 4 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…for MSX sources (Wood & Cohen 2001) and in the range 6−8 for the Arecibo sample of OH/IR stars (Jiménez-Esteban et al 2001). For the present case the mean, J − K colour index is 0.825 from Table 1.…”

Section: The Post-agb Hypothesismentioning

confidence: 56%

Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

Marquette¹,

Tisserand

François

et al. 2008

A&A

View full text Add to dashboard Cite

Context. For seven years, the EROS-2 project obtained a mass of photometric data on variable stars. We present a peculiar Cepheid-like star, in the direction of the Small Magellanic Cloud, which demonstrates unusual photometric behaviour over a short time interval. Aims. We report on data of the photometry acquired by the MARLY telescope and spectroscopy from the EFOSC instrument for this star, called EROS2 J005135-714459(sm0060n13842), which resembles the unusual Cepheid HR 7308. Methods. The light curve of our target is analysed using the Analysis of Variance method to determine a pulsational period of 5.5675 days. A fit of time-dependent Fourier coefficients is performed and a search for proper motion is conducted. Results. The light curve exhibits a previously unobserved and spectacular change in both mean magnitude and amplitude, which has no clear theoretical explanation. Our analysis of the spectrum implies a radial velocity of 104 km s −1 and a metallicity of −0.4 ± 0.2 dex. In the direction of right ascension, we measure a proper motion of 17.4 ± 6.0 mas yr −1 using EROS astrometry, which is compatible with data from the NOMAD catalogue. Conclusions. The nature of EROS2 J005135-714459(sm0060n13842) remains unclear. For this star, we may have detected a non-zero proper motion, which would imply that it is a foreground object. Its radial velocity, pulsational characteristics, and photometric data, however, suggest that it is instead a Cepheid-like object located in the SMC. In such a case, it would present a challenge to conventional Cepheid models.

show abstract

Section: The Post-agb Hypothesismentioning

confidence: 56%

Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

Marquette¹,

Tisserand

François

et al. 2008

A&A

View full text Add to dashboard Cite

show abstract

“…IRAS 20160+2734 (AU Vul) is classified as a semi-regular pulsating star in the SIMBAD database. It was first considered a post-AGB star by Jiménez-Esteban et al (2001) during a first analysis of our present sample. Lewis et al (2004) supported this classification on the basis of the erratic detection of its different masers, being detected in the 1612 MHz OH maser at the sensitivity limit of the telescope by Eder et al (1988), non-detected later in a water maser survey by Engels & Lewis (1996) or as a mainline OH maser by Lewis (1997), and recently again detected at 1667 MHz but not at 1665 MHz by Lewis et al (2004).…”

Section: Early Post-agb Candidatesmentioning

confidence: 91%

An infrared study of galactic OH/IR stars

Jiménez-Esteban

Agudo-Mérida²,

Engels

et al. 2005

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. In this paper we present optical and near-infrared finding charts, accurate astrometry (≈1 ) and single-epoch nearinfrared photometry for 371 IRAS sources, 96% of those included in the so-called "Arecibo sample of OH/IR stars" (Eder et al. 1988, ApJS, 66, 183; Lewis et al. 1990a, ApJ, 362, 634; Chengalur et al. 1993, ApJS, 89, 189). The main photometric properties of the stars in the sample are presented and discussed as well as the problems found during the process of identification of the optical/near-infrared counterparts. In addition, we also identify suitable reference stars in each field to be used for differential photometry purposes in the future. We find that 39% of the sources (144 in number) have no optical counterpart, 8 of them being invisible even at near infrared wavelengths. The relative distribution of sources with and without optical counterpart in the IRAS two-colour diagram and their characteristic near infrared colours are interpreted as the consequence of the increasing thickness of their circumstellar shells. Among the objects not detected at near infrared wavelengths four non-variable sources are proposed to be heavily obscured post-AGB stars which have just very recently left the AGB. Eight additional objects with unusually bright and/or blue nearinfrared colours are identified as candidate post-AGB stars and/or proto-planetary nebulae.

show abstract

“…This paper investigates these scenarios. Jiménez-Esteban et al (2001) find that OH /IR stars lie on a linear locus in a J À H versus J À K two-color plot. A more common plot is J À H versus H À K. Whitelock et al (1994) find that the NIR colors of their sample of Mira variables fall on the blue H À K range from 0.4 to $0.9, which generally corresponds with thin, translucent circumstellar shells dominated by a stellar radiation field.…”

Section: Introductionmentioning

confidence: 99%

On Modeling the Near-Infrared Two-Color Locus of OH/IR Stars with a ConstantdM/dt

Lewis¹

2006

Astron J

View full text Add to dashboard Cite

OH /IR stars fall on a well-defined locus in two-color near-IR (NIR) plots. This locus is replicated by a sequence of self-consistent radiative-transfer models of shells with long-term constant mass loss provided that (1) the initial stellar spectral energy distribution has NIR colors matching those at the foot of the locus and (2) a cold-silicate dust opacity function is used. The models depend on the public code DUSTY. The NIR locus is also followed by models of detached shells: our models are based on shells generated by a constant dM /dt within which a central hole grows, so an expansion-time chronology can be attached to the color evolution of a detached shell. This also provides an upper limit on the time for 1612 MHz masers to disappear after dM /dt ! 0. The brevity of this timescale shows that the pumping of 1612 MHz masers is very dependant on the reprocessing of the stellar radiation field occurring within 5r d of the star (where r d is the radius of the hottest dust), which explains why they can disappear on timescales of less than two decades. Our second concern is to explain the distribution along the NIR locus of the OH /IR stars with the reddest IRAS colors, which appear to have ''detached'' shells, even though many are mid-IR ( MIR) variables. Since the NIR locus is followed by shells generated by any form of dM /dt, whether constant, interrupted, or periodic, these MIR variables show that most thick, oxygen-rich, circumstellar shells exhibit a severe cyclical modulation in their massloss rates, as predicted by Simis in 2001.

show abstract

Near IR Observations of the Arecibo Sample of OH/IR Stars

Cited by 4 publications

References 6 publications

Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

An infrared study of galactic OH/IR stars

On Modeling the Near-Infrared Two-Color Locus of OH/IR Stars with a ConstantdM/dt

Contact Info

Product

Resources

About