HR Carinae: New spectroscopic data and physical parameters

Machado, Maria Auxiliadora Delgado; Araújo, F. X. de; Pereira, C. B.; Fernandes, M. Borges

doi:10.1051/0004-6361:20020295

Cited by 16 publications

(17 citation statements)

References 27 publications

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“…Noticing that the radius of 350 R derived by Machado et al (2002) is also larger than that obtained by us, a possible explanation for the higher mass-loss rate derived by Machado et al (2002) is that a larger radius needs a higher mass-loss rate to provide adequate particle number density.…”

Section: Hr Carmentioning

confidence: 50%

“…From MJD 2,450,110 to 2,450,262 the variation of magnitude, ÁV J , was about 0.1 mag. Therefore, the temperature could not vary from 15,000 to 10,000 K. The derived luminosity of HR Car from our models was log L/L ¼ 5:6, which was also used by Lamers et al (1996), but was lower than the value of Machado et al (2002). Machado et al (2002) derived a same temperature T eA ¼ 10; 000 K for HR Car; however, Note.-The units of T Ã are kK,Ṁ in 10 À5 M yr À1 , 1 in km s À1 , and in in 10 À11 g cm À3 .…”

Section: Hr Carmentioning

confidence: 69%

“…The mass-loss rates of most of sample stars were taken from the literature. For HR Car in the maximum state the mass-loss rate was investigated in a parameter space based on the results of Lamers et al (1996) and Machado et al (2002). The mass-loss rate of S Dor in the minimum was calculated using the predictions of Vink & de Koter (2002) and Vink et al (2001).…”

Section: Model Selectionmentioning

confidence: 99%

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Estimating the Structure and Geometry of Winds from Luminous Blue Variables via Fitting the Continuum Energy Distributions

Guo

2007

ApJ

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By combining the UV spectra from IUE with photometric data in the optical band, we present a quantitative study on the continuum energy distributions of LBVs to determine the structure and geometry of LBV winds. It is shown that the shape of continuum energy distributions around the Balmer jump is sensitive to the velocity law of LBV winds. A simple, spherically symmetric wind model including free-bound and free-free radiation is constructed to compute the continuum energy distributions of LBVs. By matching theoretical ones to the observed continuum energy distributions around the Balmer jump, we have obtained value of the exponent of the velocity law in both minimum and maximum state for five LBVs, i.e., AG Car, HR Car, R40, S Dor, and R127. We have found that is about 0.5Y0.7 in the minimum state and larger than 1.5 in the maximum state. Transitions in the ionization states of metals between the minimum and maximum state of LBVs, which lead to changes in the radiative acceleration due to spectral lines, are most likely responsible for such effect on the velocity law. We have also determined the geometry of the wind and found that a spherically symmetric wind model can well reproduce the observed continuum energy distributions of the five LBVs. Based on these results we suggest that the wind of LBVs be basically quasi-spherical, maybe with some clumpy structure in the spherical wind to produce some observed aspherical features.

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Section: Hr Carmentioning

confidence: 50%

Section: Hr Carmentioning

confidence: 69%

Section: Model Selectionmentioning

confidence: 99%

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Estimating the Structure and Geometry of Winds from Luminous Blue Variables via Fitting the Continuum Energy Distributions

Guo

2007

ApJ

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“…On the other hand, other early B hypergiants, like ζ 1 Sco or Wray 977, present strong P-Cygni profiles in He  lines (e.g., Kaper et al 2006), which are not seen in HD 80077. The main difference between the spectrum of HR Car and that of HD 80077 (in addition to the later spectral type of HR Car) is the presence of many Fe  and [Fe ] emission lines in the former (Machado et al 2002). In addition, the Hα P-Cygni of HD 80077 seen in our 2003 spectra peaks 2.6 times above the continuum level, while it only reaches ∼ 1.2 times the continuum in a sample of B1 -B2 Ia supergiants.…”

Section: Reddening and Luminositymentioning

confidence: 99%

The open cluster Pismis 11 and the very luminous blue supergiant HD 80077

Marco¹,

Negueruela²

2008

A&A

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Context. The very luminous blue supergiant HD 80077 has been claimed to be a member of the young open cluster Pismis 11, and hence a hypergiant. Membership of the cluster would mean that it is one of the brightest stars in the Galaxy, and one of the few evolved very massive stars whose distance can be accurately determined. Aims. We carry out a comprehensive study of the open cluster Pismis 11, which allows us to derive with accuracy its distance and reddening. Methods. We obtained U BVRI photometry of the cluster field and low-resolution spectroscopy of a number of putative members. We derive spectral types from the spectra and determine that the reddening in this direction is standard. We then carry out a careful photometric analysis that allows us to determine individual reddening values, deriving unreddened parameters that are used for the main sequence fit. Results. We identify 43 likely members of Pismis 11 and determine individual reddenings. We study the variation of extinction across the face of the cluster and find some dispersion, with a trend to higher values in the immediate neighbourhood of HD 80077. We estimate a distance of 3.6 kpc for the cluster. If HD 80077 is a member, it has M bol < −10.5 and it is one of the three visually brightest stars in the Galaxy. Several early type stars in the vicinity of Pismis 11 fit well the cluster sequence and are likely to represent an extended population at the same distance. About 18 ′ to the North of Pismis 11, we find a small concentration of stars, which form a clear sequence. We identify this group as a previously uncatalogued open cluster, which we provisionally call Alicante 5. The distance to Alicante 5 is also 3.6 kpc, suggesting that these two clusters and neighbouring early-type stars form a small association. Conclusions. We have identified a small association around Pismis 11, located at a distance of 3.6 kpc. Based on its proper motion, HD 80077 is not a runaway star and may be a member of the cluster. If this is the case, it would be one of the brightest stars in the Galaxy.

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“…Effective temperature determinations for HR Car range between about 10 000 K (Machado et al 2002), 14 000 ± 2000 K (see above), 17 900 K (Groh et al 2009), and 22 000 K (Hohle et al 2010). The star is highly variable: it had its last S Dor outburst in July 2001 and is currently in a quiet state, two magnitudes fainter than at maximum (in V).…”

Section: Introductionmentioning

confidence: 99%

The luminous blue variable HR Carinae has a partner

Boffin

Rivinius

Mérand

et al. 2016

A&A

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Luminous blue variables (LBVs) are massive stars caught in a post-main sequence phase, during which they lose a significant amount of mass. Since, on one hand, it is thought that the majority of massive stars are close binaries that will interact during their lifetime, and on the other, the most dramatic example of an LBV, η Car, is a binary, it would be useful to find other binary LBVs. We present here interferometric observations of the LBV HR Car done with the AMBER and PIONIER instruments attached to ESO's Very Large Telescope Interferometer (VLTI). Our observations, spanning two years, clearly reveal that HR Car is a binary star. It is not yet possible to fully constrain the orbit, and the orbital period may lie between a few years and several hundred years. We derive a radius for the primary in the system and possibly also resolve the companion. The luminosity ratio in the H-band between the two components is changing with time, going from about 6 to 9. We also tentatively detect the presence of some background flux which remained at the 2% level until January 2016, but then increased to 6% in April 2016. Our AMBER results show that the emission line-forming region of Brγ is more extended than the continuum-emitting region as seen by PIONIER and may indicate some wind-wind interaction. Most importantly, we constrain the total masses of both components, with the most likely range being 33.6 M and 45 M. Our results show that the LBV HR Car is possibly an η Car analog binary system with smaller masses, with variable components, and further monitoring of this object is definitively called for.

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HR Carinae: New spectroscopic data and physical parameters

Cited by 16 publications

References 27 publications

Estimating the Structure and Geometry of Winds from Luminous Blue Variables via Fitting the Continuum Energy Distributions

Estimating the Structure and Geometry of Winds from Luminous Blue Variables via Fitting the Continuum Energy Distributions

The open cluster Pismis 11 and the very luminous blue supergiant HD 80077

The luminous blue variable HR Carinae has a partner

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