The long-period Galactic Cepheid RS Puppis

Kervella, P.; Mérand, A.; Szabados, László; Sparks, W. B.; Havlen, R. J.; Bond, Howard E.; Pompei, E.; Fouqué, P.; Bersier, D.; Cracraft, M.

doi:10.1051/0004-6361/201117674

Cited by 13 publications

(30 citation statements)

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“…The long-period Cepheid RS Pup is a particularly interesting object due to its location in a large reflection nebula (Westerlund 1961;Kervella et al 2008Kervella et al , 2012Feast 2008) and erratic period changes (Berdnikov et al 2009) that are also clearly seen in the present data. As the Coralie data shows, using non-contemporaneously determined ΔR and ΔΘ can lead to systematic errors of up to 7% for its BW distance.…”

Section: Rs Puppissupporting

confidence: 70%

Tuning in on Cepheids: Radial velocity amplitude modulations

Anderson

2014

A&A

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Context. Classical Cepheids are crucial calibrators of the extragalactic distance scale. The Baade-Wesselink technique can be used to calibrate Cepheid distances using Cepheids in the Galaxy and the Magellanic Clouds. Aims. I report the discovery of modulations in radial velocity (RV) curves of four Galactic classical Cepheids and investigate their impact as a systematic uncertainty for Baade-Wesselink distances.Methods. Highly precise Doppler measurements were obtained using the Coralie high-resolution spectrograph since 2011. Particular care was taken to sample all phase points in order to very accurately trace the RV curve during multiple epochs and to search for differences in linear radius variations derived from observations obtained at different epochs. Different timescales are sampled, ranging from cycle-to-cycle to months and years. Results. The unprecedented combination of excellent phase coverage obtained during multiple epochs and high precision enabled the discovery of significant modulation in the RV curves of the short-period s-Cepheids QZ Normae and V335 Puppis, as well as the long-period fundamental mode Cepheids Carinae and RS Puppis. The modulations manifest as shape and amplitude variations that vary smoothly on timescales of years for short-period Cepheids and from one pulsation cycle to the next in the long-period Cepheids. The order of magnitude of the effect ranges from several hundred m s −1 to a few km s −1 . The resulting difference among linear radius variations derived using data from different epochs can lead to systematic errors of up to 15% for Baade-Wesselink-type distances, if the employed angular and linear radius variations are not determined contemporaneously. Conclusions. The different natures of the Cepheids exhibiting modulation in their RV curves suggests that this phenomenon is common. The observational baseline is not yet sufficient to conclude whether these modulations are periodic. To ensure the accuracy of Baade-Wesselink distances, angular and linear radius variations should always be determined contemporaneously.

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Section: Rs Puppissupporting

confidence: 70%

Tuning in on Cepheids: Radial velocity amplitude modulations

Anderson

2014

A&A

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“…This wavelength range is an optimal choice in terms of scattered light intensity, because the high flux from the yellow supergiant combines with the efficient scattering from the dust. Since the field-of-view (FoV) of the ACS/WFC polarizers (an unvignetted circular FoV with diameter 70 ) is smaller than the ∼3 size of the RS Pup nebula, we positioned the Cepheid near the edge of the FoV, and we focused on a bright, high polarization area of the nebula that was identified by Kervella et al (2012). Seven epochs of polarimetric imaging, equally spaced throughout a single pulsation cycle of RS Pup, were obtained between 2010 March 25 and April 29.…”

Section: Instrumental Setup and Raw Data Reductionmentioning

confidence: 99%

The long-period Galactic Cepheid RS Puppis

Kervella

Bond

Cracraft

et al. 2014

A&A

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As one of the most luminous Cepheids in the Milky Way, the 41.5-day RS Puppis is an analog of the long-period Cepheids used to measure extragalactic distances. An accurate distance to this star would therefore help anchor the zero-point of the bright end of the period-luminosity relation. But, at a distance of about 2 kpc, RS Pup is too far away for measuring a direct trigonometric parallax with a precision of a few percentage points with existing instrumentation. RS Pup is unique by being surrounded by a reflection nebula whose brightness varies as pulses of light from the Cepheid propagate outward. We present new polarimetric imaging of the nebula obtained with HST/ACS. The derived map of the degree of linear polarization p L allows us to reconstruct the three-dimensional structure of the dust distribution. To retrieve the scattering angle from the p L value, we consider two different polarization models, one based on a Milky Way dust mixture and one assuming Rayleigh scattering. Considering the derived dust distribution in the nebula, we adjust a model of the phase lag of the photometric variations over selected nebular features to retrieve the distance of RS Pup. We obtain a distance of 1910 ± 80 pc (4.2%), corresponding to a parallax of π = 0.524 ± 0.022 mas. The agreement between the two polarization models that we considered is good, but the final uncertainty is dominated by systematics in the adopted model parameters. The distance we obtain is consistent with existing measurements from the literature, but light echoes provide a distance estimate that is not subject to the same systematic uncertainties as other estimators (e.g., the Baade-Wesselink technique). RS Pup therefore provides an important fiducial for calibrating the systematic uncertainties of the long-period Cepheid distance scale.

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“…Although our current spatial resolution is comparatively coarse, we are able to place a 3σ upper limit on the mass of neutral atomic hydrogen within a radius of 38,000 AU from the star (i.e., one synthesized beam) of < M 0.11 HI ( Table 5). Looking to larger scales, Kervella et al (2012) found a mean radius of the RSPup reflection nebula to be ¢ 1.8 (∼0.8 pc for our adopted distance) based on the analysis of scattered light images, and they estimated the total quantity of gas plus dust within this volume to be…”

Section: Rs Pupmentioning

confidence: 95%

“…However, we find no statistically significant emission near the position of RSPup either in our H I channel maps (not shown) or in our integrated spectra. Over the total angular extent of the reflection nebula (~¢ 4 ; Kervella et al 2012), spatial filtering of emission by VLA should not be a factor (see Section 3). We conclude that any atomic hydrogen associated with mass loss from RSPup or with the RSPup reflection nebula is either below our detection threshold or lies at velocities affected by confusion from line-of-sight emission.…”

Section: Rs Puppis (Rs Pup)mentioning

confidence: 99%

“…Because the mass loss on the instability strip is expected to extend over tens of thousands of years or more, ejecta may be spread well beyond a single beam diameter-possible reaching a parsec or more from the star (see M12; Kervella et al 2012, Section 4.1). For each undetected star, we therefore also compute upper limits on the total H I mass within a fiducial volume of radius 0.5 pc.…”

Section: Upper Limits On the Circumstellar H I Mass And Mass-loss Ratmentioning

confidence: 99%

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A SEARCH FOR MASS LOSS ON THE CEPHEID INSTABILITY STRIP USING H i 21 cm LINE OBSERVATIONS

Matthews

Marengo

Evans

2016

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We present the results of a search for H I 21 cm line emission from the circumstellar environments of four Galactic Cepheids (RS Pup, X Cyg, ζ Gem, and T Mon) based on observations with the Karl G. Jansky Very Large Array. The observations were aimed at detecting gas associated with previous or ongoing mass loss. Near the long-period Cepheid TMon, we report the detection of a partial shell-like structure whose properties appear consistent with originating from an earlier epoch of Cepheid mass loss. At the distance of TMon, the nebula would have a mass (H I+He) of~ M 0.5 , or ∼6% of the stellar mass. Assuming that one-third of the nebular mass comprises sweptup interstellar gas, we estimate an implied mass-loss rate of~´-No clear signatures of circumstellar emission were found toward ζGem, RSPup, or XCyg, although in each case, line-of-sight confusion compromised portions of the spectral band. For the undetected stars, we derive model-dependent s 3 upper limits on the mass-loss rates, averaged over their lifetimes on the instability strip, of ´-10 6 ( -) yr −1 and estimate the total amount of mass lost to be less than a few percent of the stellar mass.

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The long-period Galactic Cepheid RS Puppis

Cited by 13 publications

References 30 publications

Tuning in on Cepheids: Radial velocity amplitude modulations

Tuning in on Cepheids: Radial velocity amplitude modulations

The long-period Galactic Cepheid RS Puppis

A SEARCH FOR MASS LOSS ON THE CEPHEID INSTABILITY STRIP USING H i 21 cm LINE OBSERVATIONS

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