The Distances of the Magellanic Clouds

Walker, A. R.

doi:10.1007/978-94-011-4734-7_8

Cited by 45 publications

(28 citation statements)

References 95 publications

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“…We adopted the spectral type to temperature calibration and bolometric correction from Schmidt-Kaler (1982). The LMC distance modulus was taken to be 18.5 (see Walker 1999).…”

Section: The Hr-diagrammentioning

confidence: 99%

On the nature of pre-main sequence candidate stars in the Large Magellanic Cloud

Wit¹,

Beaulieu

Lamers

et al. 2005

A&A

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Abstract. We investigate a sample of 18 Large Magellanic Cloud Herbig Ae/Be candidate stars looking at their (1) spectral types (2) brightness variability mechanism and (3) near infra-red JHK emission. We find that the majority of the target stars have Hα emission, are of spectral type early-to mid-B and lack strong JHK excess emission. Their Balmer decrements are found to be similar to that of Galactic Be stars in general. Their erratic brightness variability is evaluated by using the observed optical color excess and the color gradient from the light curves and is subsequently interpreted as being due to variable dust obscuration or variable bf-ff emission from circumstellar ionized gas. For approximately half of the target stars in our sample the type of variability seems to be dissimilar to the mechanism involving bound-free and free-free emission, but could be interpreted as caused by variable dust obscuration, as we have proposed in earlier studies. It is therefore suggested that they are pre-main sequence objects, despite the fact that they nearly all lack thermal dust emission in the near infra-red; mid/far infra-red observations for these objects are warranted. One star is observed to have JHK excess emission and an inspection of its 7.5 year MACHO light curve confirms its erratic photometric behavior. The object displays deep photometric minima with a quasi-period of 191.3 days, as generally seen in the Galactic pre-main sequence subgroup of the UX Orionis stars.

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“…We adopted the spectral type to temperature calibration and bolometric correction from Schmidt-Kaler (1982). The LMC distance modulus was taken to be 18.5 (see Walker 1999).…”

Section: The Hr-diagrammentioning

confidence: 99%

On the nature of pre-main sequence candidate stars in the Large Magellanic Cloud

Wit¹,

Beaulieu

Lamers

et al. 2005

A&A

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“…We applied the calibration of T eff and the bolometric correction for luminosity class III stars (Schmidt-Kaler 1982) to the resulting three estimates of (B − V) 0 for every object. Extinction due to dust with R V = 3.0 and a LMC distance modulus of 18.50 was adopted (for a recent discussion about the LMC distance determination, see Walker 1999).…”

Section: The Derivation Of the Elhc Stellar Parametersmentioning

confidence: 99%

A Search for HAeBe stars in the bar of the Large Magellanic Cloud based on optical variability

Wit

Beaulieu

Lamers

2002

A&A

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Abstract. We searched the EROS1 database consisting of 80 000 stars in the bar of the Large Magellanic Cloud for blue objects with irregular photometric behavior similar to Galactic Herbig Ae/Be (HAeBe) stars. We found 14 new objects in addition to the discovery of 7 HAeBe candidate stars found in our previous studies. Based on their light curve and colours we classify these new objects also as EROS LMC HAeBe Candidates (ELHCs). The objects are located in an area of enhanced 60 µm emission, which indicates a star forming region. The stars are concentrated in three areas and the majority of the objects are clustered round the N 120 nebular complex. The light curves are interpreted with a simple model, involving obscuration by an inhomogeneous orbiting circumstellar dust cloud as the dominant cause of the variability. We find that the dust orbiting the stars is at a radial distance in the order of 10 to a few 100 AUs. Most of the objects are "bluer-when-fainter". This is attributed to the presence of a (blue) scattering nebula with a size smaller than the point spread function of the photometric images. The stellar parameters are derived from the photometry. The luminosity of the stars is in the range of 3.4 < log(L/L ) < 4.2 and the colours indicate spectral types O or B. The stars are located in the HR-diagram above the birthline for Galactic stars by about 1 dex in luminosity. The method used to detect the ELHCs stars on optical variability criteria is discussed. We show that our sample of HAeBe candidates in the EROS1 field of view is complete up to V 16.5 m for the typical amplitude and time scale of the ELHCs.

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“…More uncertain is the distance to the supernova. This is uncertain to ∼10% (Walker 1998;Lundqvist & Sonneborn 2001), and a conservative limit is given by Gibson (2000), corresponding to an uncertainty in the line flux of ∼27%. Because the modeled f 26µm scales almost linearly with M ( 44 Ti) (Sect.…”

Section: Uncertainties In the Modelingmentioning

confidence: 99%

ISO/SWS observations of SN 1987A

Lundqvist

Kozma

Sollerman

et al. 2001

A&A

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Ti. Assessing various uncertainties of the model, and checking the late optical emission it predicts, we obtain an upper limit of 1.1 × 10 −4 M . This is lower than in our previous estimate using other ISO data, and we compare our new result with other models for the late emission, as well as with expected yields from explosion models. We also show that steady-state models for the optical emission are likely to overestimate the mass of ejected 44 Ti. The low limit we find for the mass of ejected 44 Ti could be higher if dust cooling is important. A direct check on this is provided by the gamma-ray emission at 1.157 Mev as a result of the radioactive decay of 44 Ti.

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The Distances of the Magellanic Clouds

Cited by 45 publications

References 95 publications

On the nature of pre-main sequence candidate stars in the Large Magellanic Cloud

On the nature of pre-main sequence candidate stars in the Large Magellanic Cloud

A Search for HAeBe stars in the bar of the Large Magellanic Cloud based on optical variability

ISO/SWS observations of SN 1987A

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