The Masses of White Dwarfs in the Praesepe Open Cluster

Claver, C. F.; Liebert, James; Bergeron, P.; Koester, D.

doi:10.1086/323792

Cited by 86 publications

(133 citation statements)

References 36 publications

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“…Thus, the large spread could be explained by considering that maybe these two objects are field stars. However, the sample of white dwarfs in the Praesepe cluster has been well studied (Claver et al 2001;Dobbie et al 2004) and it is unlikely that these stars do not belong to the cluster. The Hyades contain a large number of white dwarfs, for which the initial and final masses have been derived with accuracy.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Testing the Initial–Final Mass Relationship of White Dwarfs

Catalán

Isern

Garcı́a–Berro

et al. 2010

Astrophysics and Space Science Proceedings

113

184

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A mis padres y hermana AgraïmentsEn primer lloc vull agrair als meus directors de tesi, Jordi Isern i Enrique García-Berro, que em donessin l'oportunitat de realitzar el doctorat a l'IEEC (al CSIC i a la UPC), així com que em proporcionessin tot el suport necessari. Crec que he après moltes coses importants en aquestsúltims anys, no només en la part científica, i això en partés una conseqüència d'haver treballat amb ells. Els vull donar les gràcies també pel suport i la confiança dipositada en mi, especialment durant aquestúltim any de feina.Durant tota aquestaèpoca he tingut la sort de tenir uns companys fantàstics que m'han fet molt més fàcil la feina. Primer vaig conèixer l'Alina, la meva companya de "fatigas" i després el Jose, el Pep i el Miquel. Més tard s'hi van afegir l'Ignasi, la Violeta, l'Anna C., l'Anna A., el Carlo, el Moi, el Nil, l'Anaïs. . . Tots els moments que hem compartit dins i fora de l'IEEC han estat molt importants per a mi i m'emporto un gran record de tota aquestaèpoca, primer al Nexus, després a la UAB i finalment a l'ETSE. Ara que tinc la oportunitat, els hi vull agrair als meus companys, o més ben dit, amics, tots elsànims i suport que m'han donat. També els hi vull donar les gràcies al personal d'administració i a la resta de companys que he tingut durant aquests anys.En especial, l'Ignasi es mereix un gran gràcies. . . Primer de tot, per venir a l'IEEC en un moment en que la meva feina necessitava d'un observador amb experiència. Per tenir la generositat de compartir els seus coneixements amb mi durant aquests anys, per acompanyar-me en les observacions, per tenir sempre tanta confiança en mi, molta més que jo mateixa i per ajudar-me sempre que se li presentés la oportunitat. Els seusànims i el seu suport han estat essencials per a que arribés aquest moment i per tant, només em queda donar-li el meu agraïment més sincer.También le debo un agradecimiento especial a Carlos Allende Prieto, que sin ni siquiera conocerme en persona aceptó acompañarme a observar al McDonald Observatory durante 10 días. Su ayuda y dedicación en la distancia, especialmente en el análisis de las compañeras de las enanas blancas, han sido también vitales para el desarrollo de esta tesis.Durante mi doctorado he tenido la oportunidad de disfrutar de estancias en otros centros. Le quiero dar las gracias a Inma Domínguez, Carlos Abia y Olga Zamora de la Universidad de Granada por la atención que me dispensaron cuando estuve allí. También quisiera dar las gracias a Roberto Silvotti y Juan Alcalá por la ayuda y el buen trato que me dieron durante el tiempo que pasé en el Osservatorio Astronomico di Capodimonte. Gracias también al resto de personas que trabajan en el Osservatorio y que hicieron mi estancia muy agradable.A mi profesor Manolo Segura le quiero agredecer que en su día me hiciera creer en mis posibilidades y despertara mi afán por intentar superarme poco a poco. Muchas gracias también por la "contingencia" y por la confianza dipositada en mí.En un momento para mí tan importante comoéste no me puedo olvi...

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Section: Discussionmentioning

confidence: 99%

“…We have used the data of Claver et al (2001) for the Hyades and part of the Praesepe sample. We have included also two stars studied by Dobbie et al (2004) and some recent results of six new stars (Dobbie et al 2006).…”

Section: Other Available Datamentioning

confidence: 99%

Testing the Initial–Final Mass Relationship of White Dwarfs

Catalán

Isern

Garcı́a–Berro

et al. 2010

Astrophysics and Space Science Proceedings

113

184

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“…It has been suggested (see, e.g., Eggen & Iben 1988 ; see also Barstow et al 1997, their°6.1) that the paradox of the hot WD in V471 Tau could be resolved if the system really is much younger than other members of the Hyades, having 5 Curiously, the Praesepe cluster also contains a high-mass WD, LB 5893, that is anomalously hot for its mass, as shown by Reid (1996), Claver, Liebert, & Bergeron (1997), and Claver et al (2001) ; although LB 5893 is a single WD, it presents a paradox similar to that of V471 Tau. Table 3 ; gravitational-redshift masses are plotted for the single white dwarfs and our dynamical mass for V471 Tau.…”

Section: Recent Star Formationmentioning

confidence: 95%

“…Clemens et al (1992) showed that the X-ray and optical modulations are 180¡ out of phase and argued that they arise because of magnetic accretion from the K dwarfÏs wind onto the pole(s) of the WD. In this picture, the WDÏs rotation period is 9.25 minutes, and metallic opacity darkens the pole(s) of the WD in soft X-rays while brightening them through Ñux redistribution in the optical (see Dupuis et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Hubble Space TelescopeSpectroscopy of V471 Tauri: Oversized K Star, Paradoxical White Dwarf

O'Brien

Bond

Sion

2001

ApJ

109

106

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We have used the Goddard High Resolution Spectrograph on board the Hubble Space T elescope to obtain Lya spectra of the hot white dwarf (WD) component of the short-period eclipsing DA]dK2 precataclysmic binary V471 Tauri, a member of the Hyades star cluster. Radial velocities of the WD were determined from eight post-COSTAR spectra obtained near the two quadratures of the orbit. When combined with ground-based measurements of the dK velocities, eclipse timings, and a determination of the dK starÏs rotational velocity, the data constrain the orbital inclination to be i \ 77¡ and yield dynamical masses for the components of and Model atmosphere M WD \ 0.84 M dK \ 0.93 M _ . Ðtting of the Lya proÐle provides the e †ective temperature (34,500 K) and surface gravity (log g \ 8.3) of the WD. The radius of the dK component is about 18% larger than that of a normal Hyades dwarf of the same mass. This expansion is attributed to the large degree of coverage of the stellar surface by starspots, which is indicated by both radiometric measurements and ground-based Doppler imaging ; in response, the star has expanded in order to maintain the luminosity of a 0.93 dwarf. The radius of M _ the WD, determined from a radiometric analysis and from eclipse ingress timings, is 0.0107 The R _ . position of the star in the mass-radius plane is in full accord with theoretical predictions for a degenerate carbon-oxygen WD with a surface temperature equal to that observed. The position of the WD in the H-R diagram is also fully consistent with that expected for a WD with our dynamically measured mass. Both comparisons with theory are probably the most stringent yet made for any WD. The theoretical cooling age of the WD is 107 yr. The high e †ective temperature and high mass of the WD present an evolutionary paradox. The WD is the most massive one known in the Hyades but also the hottest and youngest, in direct conÑict with expectation. We examine possible resolutions of the paradox, including the possibility of a nova outburst in the recent past, but conclude that the most likely explanation is that the WD is indeed very young and is descended from a blue straggler. A plausible scenario is that the progenitor system was a triple, with a close inner pair of main-sequence stars whose masses were both similar to that of the present cluster turno †. These stars became an Algol-type binary, which merged after several hundred million years to produce a single blue straggler of about twice the turno † mass. When this star evolved to the asymptotic giant branch phase, it underwent a common envelope interaction with a distant dK companion, which spiraled down to its present separation, and ejected the envelope. We estimate that the common envelope efficiency parameter was on the order of 0.3È1.0, in a CE good agreement with recent hydrodynamical simulations.

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“…Magnetic fields, alongside angular momentum, were also proposed to be an effective factor of the mass-loss, after the discovery of a magnetic white dwarf (MWD) WD 0836+201 as a probable member of the Praesepe cluster (EG59, Claver et al 2001;Catalán et al 2008a). Note that it was mislabeled in both works as explained in Casewell et al (2009).…”

Section: Introductionmentioning

confidence: 99%

The progenitors of magnetic white dwarfs in open clusters

Külebi

Kalirai

Jordan

et al. 2013

A&A

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Context. White dwarfs are the final stages of stellar evolution for most stars in the galaxy and magnetic white dwarfs (MWDs) represent at least ten percent of the whole sample. According to the fossil-field hypothesis magnetic fields are remnants of the previous stages of evolution. However, population synthesis calculations are unable to reproduce the MWD sample without binary interaction or inclusion of a population of progenitor with unobservable small-scale fields. Aims. One necessary ingredient in population synthesis is the initial-to-final-mass relation (IFMR) which describes the mass-loss processes during the stellar evolution. When white dwarfs are members of open clusters, their evolutionary histories can be assessed through the use of cluster properties. This enables an independent way of determining the mass of their progenitors. The discovery of the magnetic WD 0836+201 in the Praesepe cluster prompted the question whether magnetic fields affect the IFMR. In this work we investigate this suggestion through investigations of all three known MWDs in open clusters. Methods. We assess the cluster membership by correlating the proper-motion of MWDs with the cluster proper-motion and by analyzing the candidates spectroscopically with our magnetic model spectra in order to estimate the effective temperature and radii. Furthermore, we use mass-radius relations and evolutionary models to constrain the histories of the probable cluster members. Results. We identified SDSS J085523.87+164059.0 to be a proper-motion member of Praesepe. We also included the data of the formerly identified cluster members NGC 6819-8, WD 0836+201 and estimated the mass, cooling age and the progenitor masses of the three probable MWD members of open clusters. According to our analysis, the newly identified cluster member SDSS J085523.87+164059.0 is an ultra-massive MWD of mass 1.12 ± 0.11 M . Conclusions. We increase the sample of MWDs with known progenitor masses to ten, with the rest of the data coming from the common proper motion binaries. Our investigations show that, when effects of the magnetic fields are included in the diagnostics, the estimated properties of these cluster MWDs do not show evidence for deviations from the IFMR. Furthermore we estimate the precision of the magnetic diagnostics which would be necessary to determine quantitatively whether magnetism has any effect on the mass-loss.

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The Masses of White Dwarfs in the Praesepe Open Cluster

Cited by 86 publications

References 36 publications

Testing the Initial–Final Mass Relationship of White Dwarfs

Testing the Initial–Final Mass Relationship of White Dwarfs

Hubble Space TelescopeSpectroscopy of V471 Tauri: Oversized K Star, Paradoxical White Dwarf

The progenitors of magnetic white dwarfs in open clusters

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