Classical Cepheid Pulsation Models. X. The Period‐Age Relation

Bono, G.; Marconi, M.; Cassisi, S.; Caputo, F.; Gieren, W.; Pietrzyński, G.

doi:10.1086/427744

Cited by 155 publications

(267 citation statements)

References 54 publications

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“…The standard deviation deduced from all age estimates for QZ Nor and V340 Nor is στ ∼ 12 Myr (see also Figs. 3 and 8 in Bono et al 2005). …”

Section: Conclusion and Future Researchmentioning

confidence: 96%

“…However, Bono et al (2005) argued that the age offset between QZ Nor and V340 Nor could be mitigated by using a period- age-color relation derived from models, and the reader is referred to that study for details. Bono et al (2005) concluded that the age spread is reduced from 44 Myr (period-age) to 23 Myr (period-age-color). The period difference between GU Nor (P ∼ 3 d .5) and V340 Nor is sizable (8 d ).…”

Section: Ngc 6067: Distancementioning

confidence: 99%

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Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Majaess¹,

Sturch

Bidin

et al. 2013

Astrophys Space Sci

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Cepheids are key to establishing the cosmic distance scale. Therefore it's important to assess the viability of QZ Nor, V340 Nor, and GU Nor as calibrators for Leavitt's law via their purported membership in the open cluster NGC 6067. The following suite of evidence confirms that QZ Nor and V340 Nor are members of NGC 6067, whereas GU Nor likely lies in the foreground: (i) existing radial velocities for QZ Nor and V340 Nor agree with that established for the cluster (−39.4 ± 0.2(σx) ± 1.2(σ) km/s) to within 1 km/s, whereas GU Nor exhibits a markedly smaller value; (ii) a steep velocity-distance gradient characterizes the sight-line toward NGC 6067, thus implying that objects sharing common velocities are nearly equidistant; (iii) a radial profile constructed for NGC 6067 indicates that QZ Nor is within the cluster bounds, despite being 20 ′ from the cluster center; (iv) new BV JH photometry for NGC 6067 confirms the cluster lies d = 1.75 ± 0.10 kpc distant, a result that matches Wesenheit distances computed for QZ Nor/V340 Nor using the Benedict et al. (2007, HST parallaxes) calibration. QZ Nor is a cluster Cepheid that should be employed as a calibrator for the cosmic distance scale.

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“…The standard deviation deduced from all age estimates for QZ Nor and V340 Nor is στ ∼ 12 Myr (see also Figs. 3 and 8 in Bono et al 2005). …”

Section: Conclusion and Future Researchmentioning

confidence: 96%

Section: Ngc 6067: Distancementioning

confidence: 99%

Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Majaess¹,

Sturch

Bidin

et al. 2013

Astrophys Space Sci

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“…Although there is a hint that the spread in M V magnitude is largest near the instability strip, a A147, page 11 of 16 A&A 532, A147 (2011) considerable scatter remains outside the boundaries of the strip, so it is questionable whether this can be the whole explanation. Observations of Cepheids might, however, shed light on possible age spreads within the clusters via the period-age relation (Efremov 2003;Bono et al 2005).…”

Section: Cepheidsmentioning

confidence: 99%

Resolved photometry of extragalactic young massive star clusters

Larsen

Mink

Eldridge

et al. 2011

A&A

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Aims. We present colour-magnitude diagrams (CMDs) of young massive star clusters in several galaxies located well beyond the Local Group. The richness of these clusters allows us to obtain large samples of post-main sequence stars and test how well the observed CMDs are reproduced by canonical stellar isochrones. Methods. We use imaging of seven clusters in the galaxies NGC 1313, NGC 1569, NGC 1705, NGC 5236 and NGC 7793 obtained with the Advanced Camera for Surveys on board the Hubble Space Telescope and carry out PSF-fitting photometry of individual stars in the clusters. The clusters have ages in the range ∼(5−50) × 10 6 years and masses of ∼10 5 M -10 6 M . Although crowding prevents us from obtaining photometry in the inner regions of the clusters, we are still able to measure up to 30-100 supergiant stars in each of the richest clusters. The resulting CMDs and luminosity functions are compared with photometry of artificially generated clusters, designed to reproduce the photometric errors and completeness as realistically as possible.Results. In agreement with previous studies, our CMDs show no clear gap between the H-burning main sequence and the Heburning supergiant stars, contrary to predictions by common stellar isochrones. In general, the isochrones also fail to match the observed number ratios of red-to-blue supergiant stars, although the difficulty of separating blue supergiants from the main sequence complicates this comparison. In several cases we observe a large spread (1-2 mag) in the luminosities of the supergiant stars that cannot be accounted for by observational errors. We find that this spread can be reproduced by including an age spread of ∼(10−30) × 10 6 years in the models. However, age spreads cannot fully account for the observed morphology of the CMDs and other processes, such as the evolution of interacting binary stars, may also play a role. Conclusions. Colour-magnitude diagrams can be successfully obtained for massive star clusters out to distances of at least 4-5 Mpc. Comparing such CMDs with models based on canonical isochrones we find several areas of disagreement. One interesting possibility is that an age spread of up to ∼30 Myr may be present in some clusters. The data presented here may provide useful constraints on models for single and/or binary stellar evolution.

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“…Such a considerable mass should be observable as a CSE similar to RS Pup at 24 and 70 μm. According to the period-age relationship established by Bono et al (2005), Car and RS Pup are between 17 and 19 million years old. As the main sequence lifetime of a 13 M star is ≈15 to 17 Myr, and assuming that the mass is lost mostly during the He burning phase, the star would have to expel of the order of 10 −6 M /year continuously over 2 Myr.…”

Section: Evolutionary Vs Pulsational Masses Of Cepheidsmentioning

confidence: 99%

The circumstellar envelopes of the Cepheids $\mathsf{\ell}$ Carinae and RS Puppis

Kervella¹,

Mérand

Gallenne

2009

A&A

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Context. Compact circumstellar envelopes (CSEs) have been detected around several Cepheids by interferometry. In particular, observations with the VINCI instrument revealed in 2006 a compact envelope around the long period Cepheid Car (P = 35.5 days). Another Cepheid, RS Pup (P = 41.4 days), presents a large (≈2 ) circumstellar nebula scattering the Cepheid light in the visible. These envelopes are particularly interesting for two reasons: their presence could impact the Cepheid distance scale, and they could imply stellar mass loss. Aims. Our goal is to establish the spatial and spectral properties of the CSEs of Car and RS Pup. This is done through a parametrization of the envelopes in terms of fractional flux (with respect to the star) and angular size. Methods. We retrieved archival Spitzer images of the two stars (λ = 3.5−70 μm), and obtained new diffraction-limited imaging with the VLT/VISIR camera in BURST mode (λ = 8.6−11.9 μm), as well as interferometric observations with the VLTI/MIDI beam combiner (λ = 8−13 μm). This combination of single-telescope and interferometric techniques allows us to probe the envelopes of the two Cepheids over a broad range of angular scales, from arcminutes to milliarcseconds. Results. The circumstellar envelope of RS Pup is resolved spatially at 24 and 70 μm by Spitzer, and around 10 μm by MIDI and VISIR. The envelope of Car appears much more compact, and is resolved only in the VISIR and MIDI observations. The infrared excesses we detect around RS Pup and Car are both very significant, but differ considerably in spectral and spatial properties. We detect a warm component in the CSE of both stars at a spatial scale of a few 100 to a few 1000 AU. In addition, RS Pup presents a very large (several 100 000 AU) and cold (≈40 K) dusty envelope. Conclusions. The observed properties of the CSEs lead us to propose that the cold dust content of the large reflection nebula surrounding RS Pup has an interstellar origin, while the warm CSEs of the two stars were created by ongoing stellar mass loss. We also speculate that the NGC 7023 reflection nebula surrounding the Herbig Be star HD 200775 is an analogue of RS Pup at an age of 100 000 years. The presence of CSEs around the two brightest long-period Cepheids is an indication that many long-period members of this class, if not all, could be surrounded by warm circumstellar envelopes created by mass loss. However, very large dusty envelopes such as that of RS Pup are probably less common, as according to our scenario, they require the presence of a high dust density in the interstellar medium (ISM) at the time of the formation of the Cepheid progenitor.

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Classical Cepheid Pulsation Models. X. The Period‐Age Relation

Cited by 155 publications

References 54 publications

Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Anchors for the cosmic distance scale: the Cepheid QZ Normae in the open cluster NGC 6067

Resolved photometry of extragalactic young massive star clusters

The circumstellar envelopes of the Cepheids $\mathsf{\ell}$ Carinae and RS Puppis

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