scholarly journals The evolution of helium white dwarfs: Applications for millisecond pulsars

2000 ◽  
Vol 177 ◽  
pp. 635-636 ◽  
Author(s):  
T. Driebe ◽  
T. Blöcker ◽  
D. Schönberner
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Mass Star ◽  
Theoretical Studies ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
Low Mass ◽  
Red Giant

Low-mass white dwarfs with helium cores (He-WDs) are known to result from mass loss and/or exchange events in binary systems where the donor is a low mass star evolving along the red giant branch (RGB). Therefore, He-WDs are common components in binary systems with either two white dwarfs or with a white dwarf and a millisecond pulsar (MSP). If the cooling behaviour of He-WDs is known from theoretical studies (see Driebe et al. 1998, and references therein) the ages of MSP systems can be calculated independently of the pulsar properties provided the He-WD mass is known from spectroscopy.

scholarly journals Millisecond Pulsar Surveys

1996 ◽  
Vol 160 ◽  
pp. 3-10 ◽  
Author(s):  
M. Bailes
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Large Scale ◽  
Planetary System ◽  
Galactic Disk ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
Sky Surveys ◽  
Unique Object ◽  
Low Mass

AbstractThere are now more than 30 millisecond pulsars known to be associated with the Galactic disk. The majority of these have been discovered in just the last few years as the result of large-scale all-sky surveys. The properties of the population vary tremendously. One unique object hosts a planetary system, more than half of those discovered possess white dwarf companions, two have extremely low-mass companions that are undergoing mass-loss and several others appear to be solitary. In this review I discuss the methods employed to find these millisecond pulsars, the parallels with early surveys for “normal” pulsars, and possible strategies for future searches.

Searching for low-mass companions around white dwarfs and subdwarfs from Kepler field

2019 ◽  
Vol 15 (S357) ◽  
pp. 41-44
Author(s):  
Jurek Krzesinski ◽  
Adam Blokesz
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Recent Observation ◽  
Type B ◽  
Stellar Envelope ◽  
Low Mass ◽  
Red Giant ◽  
Late Stages ◽  
Parent Star

AbstractKnowing the late stages of the stellar evolution is crucial for understanding the fate of planets around subdwarfs and white dwarfs. Simulations by (Staff et al.2016) show, that exoplanets engulfed in the extending stellar envelope will quickly spiral down onto the parent star. Therefore, we do not expect to find planets on close by orbits to the subdwarfs (Blokesz et al.2019) or white dwarfs. However, the recent observation of planetary debris around WD 1145+017 white dwarf suggests, there might exists planets farther away from these stars. Using binarograms, O-C diagrams and Fourier transform for the Kepler space telescope data, we investigate a problem of missing planets around white dwarfs in binary systems, single white dwarfs and subdwarfs type B. The last ones, being the only stars which (due to the lack of hydrogen) go directly to the white dwarf cooling track after their red giant phase.

scholarly journals The Temperature and Cooling Age of t h e White-Dwarf Companion to the Millisecond Pulsar PSR B1855+09

2000 ◽  
Vol 177 ◽  
pp. 633-634
Author(s):  
Jon Bell ◽  
Marten van Kerkwijk ◽  
Vicky Kaspi ◽  
Shri Kulkarni
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Measured Temperature ◽  
Millisecond Pulsar ◽  
Nuclear Burning ◽  
Low Mass ◽  
Cooling Model ◽  
Age Discrepancy

AbstractWe report on Keck and HST observations of the binary millisecond pulsar PSR B1855+09. We detect its white-dwarf companion and measuremF555W= 25.90 ± 0.12 andmF814W= 24.19 ± 0.11 (Vega system). From the reddening-corrected color we infer a temperatureTeff= 4800 ± 800 K. The companion mass is known accurately from measurements of the Shapiro delay of the pulsar signal,. Given a cooling model, one can use the measured temperature to determine the cooling age. The main uncertainty in the cooling models for such low-mass white dwarfs is the amount of residual nuclear burning, which depends on the thickness of the hydrogen layer surrounding the helium core. For PSR B1855+09, such models lead to a cooling age of ∼10Gyr, which is twice the spin-down age of the pulsar. It may be that the pulsar does not brake (n=3.0) like a dipole rotatingin vacuo. For other pulsar companions, however, ages well over lOGyr are inferred, indicating that the problem may lie with the cooling models. There is no age discrepancy for models in which the white dwarfs are formed with thinner hydrogen layers (< 3 × 10−4M⊙). See van Kerkwijk et al. ApJ (submitted) for more details.

scholarly journals Searching for optical companions to four binary millisecond pulsars with the Gran Telescopio Canarias

2020 ◽  
Vol 492 (2) ◽  
pp. 3032-3040 ◽  
Author(s):  
A Yu Kirichenko ◽  
A V Karpova ◽  
D A Zyuzin ◽  
S V Zharikov ◽  
E A López ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Optical Data ◽  
Pure Hydrogen ◽  
Millisecond Pulsars ◽  
Upper Limit ◽  
Photometric Observations ◽  
Low Mass

ABSTRACT We report on multiband photometric observations of four binary millisecond pulsars with the Gran Telescopio Canarias. The observations led to detection of binary companions to PSRs J1630+3734, J1741+1351, and J2042+0246 in the Sloan g′, r′, and i′ bands. Their magnitudes in the r′ band are ≈24.4, 24.4, and 24.0, respectively. We also set a 3σ upper limit on the brightness of the PSR J0557+1550 companion in the r′ band of ≈25.6 mag. Combining the optical data with the radio timing measurements and white dwarf cooling models, we show that the detected companions are cool low-mass white dwarfs with temperatures and ages in the respective ranges of (4–7) × 103 K and 2–5 Gyr. All the detected white dwarfs are found to likely have either pure hydrogen or mixed helium–hydrogen atmospheres.

scholarly journals Stellar Evolution in NGC 6791: Mass Loss on the Red Giant Branch and the Formation of Low‐Mass White Dwarfs

2007 ◽  
Vol 671 (1) ◽  
pp. 748-760 ◽  
Author(s):  
Jasonjot S. Kalirai ◽  
P. Bergeron ◽  
Brad M. S. Hansen ◽  
Daniel D. Kelson ◽  
David B. Reitzel ◽  
...  
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Low Mass ◽  
Red Giant

scholarly journals Stellar chronology with white dwarfs in wide binaries

2008 ◽  
Vol 4 (S258) ◽  
pp. 307-314 ◽  
Author(s):  
S. Catalán ◽  
A. Garcés ◽  
I. Ribas ◽  
J. Isern ◽  
E. García-Berro
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Mass Star ◽  
Cooling Process ◽  
Stellar Ages ◽  
Low Mass ◽  
The Moment

AbstractWhite dwarfs are the evolutionary end product of stars with low and intermediate masses. The evolution of white dwarfs can be understood as a cooling process, which is relatively well known at the moment. For this reason, wide binaries containing white dwarfs are a powerful tool to constrain stellar ages. We have studied several wide binaries containing white dwarfs with two different purposes: when the age of the companion of the white dwarf can be determined with accuracy, we use the binary to improve the knowledge about the white dwarf member. On the contrary, if the companion is a low-mass star with no age indicator available, the white dwarf member itself is used to calibrate the age of the system. In this contribution we present some results using both methodologies to constrain the ages of wide binaries.

scholarly journals Millisecond Pulsar Surveys

1987 ◽  
Vol 125 ◽  
pp. 13-21
Author(s):  
D. C. Backer
Keyword(s):  
Mass Transfer ◽  
Stellar Evolution ◽  
Binary Systems ◽  
Rotation Period ◽  
Millisecond Pulsar ◽  
Millisecond Pulsars ◽  
X Ray ◽  
New Class ◽  
The Past ◽  
Low Mass

In 1982 a new class of pulsars was defined by the discovery of a star with a millisecond rotation period, 1.6 ms. In the past 3.5 years two additional pulsars with millisecond periods have been discovered. The rapid spin of these pulsars is attributed to mass transfer in a low-mass binary progenitor system. This hypothesis is supported by the presence of companions in two of the three millisecond pulsars. These recent discoveries have led both to a deeper understanding of the final stages of stellar evolution in binary systems, and to closer ties between the observational study of neutron stars by radio, optical and X-ray techniques. In addition the millisecond pulsars provide precise astrophysical clocks that can be used to improve the solar-system ephemeredes and to search for a background of gravitational waves that may have been produced in the early stages of the visible universe. Old and ongoing searches for new millisecond pulsars are described in this paper.

scholarly journals The coolest extremely low-mass white dwarfs

2018 ◽  
Vol 614 ◽  
pp. A49 ◽  
Author(s):  
Leila M. Calcaferro ◽  
Leandro G. Althaus ◽  
Alejandro H. Córsico
Keyword(s):  
Mass Transfer ◽  
Mass Loss ◽  
White Dwarf ◽  
Binary Systems ◽  
Mass Range ◽  
Surface Gravity ◽  
Slight Reduction ◽  
Mechanisms Of Formation ◽  
Nuclear Burning ◽  
Low Mass

Context. Extremely low-mass white dwarf (ELM WD; M⋆ ≲ 0.18–0.20 M⊙) stars are thought to be formed in binary systems via stable or unstable mass transfer. Although stable mass transfer predicts the formation of ELM WDs with thick hydrogen (H) envelopes that are characterized by dominant residual nuclear burning along the cooling branch, the formation of ELM WDs with thinner H envelopes from unstable mass loss cannot be discarded. Aims. We compute new evolutionary sequences for helium (He) core WD stars with thin H envelopes with the main aim of assessing the lowest Teff that could be reached by this type of stars. Methods. We generate a new grid of evolutionary sequences of He-core WD stars with thin H envelopes in the mass range from 0.1554 to 0.2025 M⊙, and assess the changes in both the cooling times and surface gravity induced by a reduction of the H envelope. We also determine, taking into account the predictions of progenitor evolution, the lowest Teff reached by the resulting ELM WDs. Results. We find that a slight reduction in the H envelope yields a significant increase in the cooling rate of ELM WDs. Because of this, ELM WDs with thin H envelopes could cool down to ~2500 K, in contrast to their canonical counterparts that cool down to ~7000 K. In addition, we find that a reduction of the thickness of the H envelope markedly increases the surface gravity (g) of these stars. Conclusions. If ELM WDs are formed with thin H envelopes, they could be detected at very low Teff. The detection of such cool ELM WDs would be indicative that they were formed with thin H envelopes, thus opening the possibility of placing constraints on the possible mechanisms of formation of this type of star. Last but not least, the increase in g due to the reduction of the H envelope leads to consequences in the spectroscopic determinations of these stars.

scholarly journals Two-dimensional simulations of mixing in classical novae: The effect of white dwarf composition and mass

2018 ◽  
Vol 619 ◽  
pp. A121 ◽  
Author(s):  
Jordi Casanova ◽  
Jordi José ◽  
Steven N. Shore
Keyword(s):  
White Dwarf ◽  
Binary Systems ◽  
Main Sequence ◽  
Chemical Species ◽  
Two Dimensions ◽  
Classical Novae ◽  
Nova Shells ◽  
Solar Abundances ◽  
Low Mass ◽  
Thermonuclear Runaway

Context. Classical novae are explosive phenomena that take place in stellar binary systems. They are powered by mass transfer from a low-mass main sequence star onto either a CO or ONe white dwarf. The material accumulates for 104–105 yr until ignition under degenerate conditions, resulting in a thermonuclear runaway. The nuclear energy released produces peak temperatures of ∼0.1–0.4 GK. During these events, 10−7−10−3 M⊙ enriched in intermediate-mass elements, with respect to solar abundances, are ejected into the interstellar medium. However, the origin of the large metallicity enhancements and the inhomogeneous distribution of chemical species observed in high-resolution spectra of ejected nova shells is not fully understood. Aims. Recent multidimensional simulations have demonstrated that Kelvin-Helmholtz instabilities that operate at the core-envelope interface can naturally produce self-enrichment of the accreted envelope with material from the underlying white dwarf at levels that agree with observations. However, such multidimensional simulations have been performed for a small number of cases and much of the parameter space remains unexplored. Methods. We investigated the dredge-up, driven by Kelvin-Helmholtz instabilities, for white dwarf masses in the range 0.8–1.25 M⊙ and different core compositions, that is, CO-rich and ONe-rich substrates. We present a set of five numerical simulations performed in two dimensions aimed at analyzing the possible impact of the white dwarf mass, and composition, on the metallicity enhancement and explosion characteristics. Results. At the time we stop the simulations, we observe greater mixing (∼30% higher when measured in the same conditions) and more energetic outbursts for ONe-rich substrates than for CO-rich substrates and more massive white dwarfs.

scholarly journals White Dwarf Stars

2017 ◽  
Vol 45 ◽  
pp. 1760023
Author(s):  
S. O. Kepler ◽  
Alejandra Daniela Romero ◽  
Ingrid Pelisoli ◽  
Gustavo Ourique
Keyword(s):  
White Dwarf ◽  
Final Stage ◽  
White Dwarfs ◽  
Sloan Digital Sky Survey ◽  
Dwarf Stars ◽  
Multiple Systems ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release ◽  
Low Mass

White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5[Formula: see text]000 to 39[Formula: see text]000. This number includes only white dwarf stars with [Formula: see text], i.e., excluding the Extremely Low Mass white dwarfs, which are necessarily the byproduct of stellar interaction.

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