Questions linked to Silvestri L, Petros AJ, Saginson RE, et al. Handwashing in the intensive care unit: a big measure with modest effects. J Hosp Infect 2005;59:172—179

Silvestri, Luciano

doi:10.1016/j.jhin.2005.04.003

Cited by 61 publications

(124 citation statements)

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“…We have developed a procedure based on χ 2 template fitting in order to automatically identify WDMS binary candidates from the SDSS DR6 spectroscopic data base (Adelman-McCarthy et al 2008). Our initial template set consisted of several dozen SDSS spectra of confirmed WDMS binaries from Eisenstein et al (2006) and Silvestri et al (2007). These spectra were chosen to sample a broad range in white-dwarf temperatures and subtypes (DA, DB and DC) as well as companion star spectral types, and to be of a high signal-to-noise ratio (S/N).…”

Section: Methodsmentioning

confidence: 99%

“…The 15 WDMS binaries containing DB (13) and DC (2) white dwarfs presented by van den Besselaar et al (2005) have been successfully identified as WDMS binaries with our template fitting algorithm. The WDMS binary sample presented by Eisenstein et al (2006) is almost entirely contained in the WDMS binary catalogue provided by Silvestri et al (2007) (see below for a detailed comparison). Only 10 objects of Eisenstein et al (2006) with available SDSS spectra are not listed in Silvestri et al (2007), and our algorithm has successfully identified these 10 systems as WDMS binaries.…”

Section: Cross-checks With Previous Wdms Binary Cataloguesmentioning

confidence: 99%

“…The WDMS binary sample presented by Eisenstein et al (2006) is almost entirely contained in the WDMS binary catalogue provided by Silvestri et al (2007) (see below for a detailed comparison). Only 10 objects of Eisenstein et al (2006) with available SDSS spectra are not listed in Silvestri et al (2007), and our algorithm has successfully identified these 10 systems as WDMS binaries. Silvestri et al (2007) claim that their catalogue contains 1253 objects, but in fact only 1228 spectra (corresponding to 1225 objects) are listed in the electronic edition of their paper and 996 systems of those appear in our catalogue.…”

Section: Cross-checks With Previous Wdms Binary Cataloguesmentioning

confidence: 99%

“…WDMS binaries appear most promising in that respect, as their stellar components are relatively simple, and the Sloan Digital Sky Survey (SDSS; York et al 2000;Stoughton et al 2002;Abazajian et al 2009) offers the possibility of dramatically increasing the number of WDMS binaries available for detailed follow-up studies. Up to date there exist four compilations of SDSS WDMS binaries, namely Eisenstein et al (2006) (obtained as part of their search of white dwarfs), Silvestri et al (2007) [which also contains Raymond et al 2003;Silvestri et al 2006 as a subset, and was claimed to be complete for SDSS Data Release 5 (DR5)], Augusteijn et al (2008) (obtained from SDSS DR5 using colour cuts plus proper motions) and Heller et al (2009) (obtained from a search for sdB stars in SDSS DR6).…”

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confidence: 99%

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Post-common envelope binaries from SDSS - VII. A catalogue of white dwarf-main sequence binaries

Rebassa‐Mansergas¹,

Gänsicke²,

Schreiber³

et al. 2009

Monthly Notices of the Royal Astronomical Society

123

152

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We present a catalogue of 1602 white‐dwarf–main‐sequence (WDMS) binaries from the spectroscopic Sloan Digital Sky Survey Data Release 6 (SDSS DR6). Among these, we identify 440 as new WDMS binaries. We select WDMS binary candidates by template fitting all 1.27 million DR6 spectra, using combined constraints in both χ2 and signal‐to‐noise ratio. In addition, we use Galaxy Evolution Explorer (GALEX) and UKIRT Infrared Sky Survey (UKIDSS) magnitudes to search for objects in which one of the two components dominates the SDSS spectrum. We use a decomposition/fitting technique to measure the effective temperatures, surface gravities, masses and distances to the white dwarfs, as well as the spectral types and distances to the companions in our catalogue. Distributions and density maps obtained from these stellar parameters are then used to study both the general properties and the selection effects of WDMS binaries in the SDSS. A comparison between the distances measured to the white dwarfs and the main‐sequence companions shows dsec > dwd for approximately one‐fifth of the systems, a tendency already found in our previous work. The hypothesis that magnetic activity raises the temperature of the inter‐spot regions in active stars that are heavily covered by cool spots, leading to a bluer optical colour compared to inactive stars, remains the best explanation for this behaviour. We also make use of SDSS–GALEX–UKIDSS magnitudes to investigate the distribution of WDMS binaries, as well as their white‐dwarf effective temperatures and companion star spectral types, in ultraviolet to infrared colour space. We show that WDMS binaries can be very efficiently separated from single main‐sequence stars and white dwarfs when using a combined ultraviolet, optical and infrared colour selection. Finally, we also provide radial velocities for 1068 systems measured from the Na iλλ8183.27, 8194.81 absorption doublet and/or the Hα emission line. Among the systems with multiple SDSS spectroscopy, we find five new systems exhibiting significant radial velocity variations, identifying them as post‐common‐envelope binary candidates.

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Section: Methodsmentioning

confidence: 99%

Section: Cross-checks With Previous Wdms Binary Cataloguesmentioning

confidence: 99%

Section: Cross-checks With Previous Wdms Binary Cataloguesmentioning

confidence: 99%

mentioning

confidence: 99%

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Post-common envelope binaries from SDSS - VII. A catalogue of white dwarf-main sequence binaries

Rebassa‐Mansergas¹,

Gänsicke²,

Schreiber³

et al. 2009

Monthly Notices of the Royal Astronomical Society

123

152

View full text Add to dashboard Cite

show abstract

“…Willems & Kolb 2004). The Sloan Digital Sky Survey (York et al 2000;Stoughton et al 2002;Adelman-McCarthy et al 2008, SDSS) is currently dramatically increasing the number of known white dwarf plus mainsequence (WDMS) binaries (Schreiber, Nebot Gomez-Moran & Schwope 2007;Silvestri et al 2007), paving the way for largescale observational PCEB population studies. We have initiated an observational programme to identify the PCEBs among the SDSS WDMS binaries, and to determine their binary parameters (Rebassa-Mansergas et al 2007;Schreiber et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Post-common envelope binaries from SDSS - III. Seven new orbital periods

Rebassa‐Mansergas

Gänsicke

Schreiber

et al. 2008

Monthly Notices of the Royal Astronomical Society

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We present follow‐up spectroscopy and photometry of 11 post‐common envelope binary (PCEB) candidates identified from multiple Sloan Digital Sky Survey (SDSS) spectroscopy in an earlier paper. Radial velocity measurements using the Na i λλ8183.27, 8194.81 absorption doublet were performed for nine of these systems and provided measurements of six orbital periods in the range Porb= 2.7– 17.4 h. Three PCEB candidates did not show significant radial velocity variations in the follow‐up data, and we discuss the implications for the use of SDSS spectroscopy alone to identify PCEBs. Differential photometry confirmed one of our spectroscopic orbital periods and provided one additional Porb measurement. Binary parameters are estimated for the seven objects for which we have measured the orbital period and the radial velocity amplitude of the low‐mass companion star, Ksec. So far, we have published nine SDSS PCEBs orbital periods, all of them Porb < 1 d. We perform Monte Carlo simulations and show that 3σ SDSS radial velocity variations should still be detectable for systems in the orbital period range of Porb∼ 1– 10 d. Consequently, our results suggest that the number of PCEBs decreases considerably for Porb > 1 d, and that during the CE phase the orbital energy of the binary star is may be less efficiently used to expel the envelope than frequently assumed.

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Using magnetic activity and Galactic dynamics to constrain the ages of M dwarfs

et al. 2008

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Abstract. We present a study of the dynamics and magnetic activity of M dwarfs using the largest spectroscopic sample of low-mass stars ever assembled. The age at which strong surface magnetic activity (as traced by Hα) ceases in M dwarfs has been inferred to have a strong dependence on mass (spectral type, surface temperature) and explains previous results showing a large increase in the fraction of active stars at later spectral types. Using spectral observations of more than 40000 M dwarfs from the Sloan Digital Sky Survey, we show that the fraction of active stars decreases as a function of vertical distance from the Galactic plane (a statistical proxy for age), and that the magnitude of this decrease changes significantly for different M spectral types. Adopting a simple dynamical model for thin disk vertical heating, we assign an age for the activity decline at each spectral type, and thus determine the activity lifetimes for M dwarfs. In addition, we derive a statistical age-activity relation for each spectral type using the dynamical model, the vertical distance from the Plane and the Hα emission line luminosity of each star (the latter of which also decreases with vertical height above the Galactic plane).

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Questions linked to Silvestri L, Petros AJ, Saginson RE, et al. Handwashing in the intensive care unit: a big measure with modest effects. J Hosp Infect 2005;59:172—179

Cited by 61 publications

References 0 publications

Post-common envelope binaries from SDSS - VII. A catalogue of white dwarf-main sequence binaries

Post-common envelope binaries from SDSS - VII. A catalogue of white dwarf-main sequence binaries

Post-common envelope binaries from SDSS - III. Seven new orbital periods

Using magnetic activity and Galactic dynamics to constrain the ages of M dwarfs

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