scholarly journals The ultracool helium-atmosphere white dwarf companion of PSR J0740+6620?

2019 ◽  
Vol 485 (3) ◽  
pp. 3715-3720 ◽  
Author(s):  
D M Beronya ◽  
A V Karpova ◽  
A Yu Kirichenko ◽  
S V Zharikov ◽  
D A Zyuzin ◽  
...  
Keyword(s):  
White Dwarf ◽  
Millisecond Pulsar ◽  
Helium Atmosphere

ABSTRACT We report detection of the likely companion of the binary millisecond pulsar (MSP) J0740+6620 with the Gran Telescopio Canarias in the r′ and i′ bands. The position of the detected starlike source coincides with the pulsar coordinates within the 1σ uncertainty of ≈0.2 arcsec. Its magnitudes are r′ = 26.51 ± 0.17 and i′ = 25.49 ± 0.15. Comparing the data with the white dwarf (WD) cooling tracks suggests that it can be an ultracool helium-atmosphere WD with the temperature ≲3500 K and cooling age ≳5 Gyr. The age is consistent with the pulsar characteristic age corrected for kinematic effects. This is the reddest source among known WD companions of MSPs. Detection of the source in other bands would be useful to clarify its properties and nature.

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 Towards Ensemble Asteroseismology of the Pulsating DB White Dwarf Stars

2002 ◽  
Vol 185 ◽  
pp. 608-609
Author(s):  
G. Handler ◽  
M.A. Wood ◽  
A. Nitta ◽  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
The Other ◽  
Archival Data ◽  
Dwarf Stars ◽  
Helium Atmosphere ◽  
Individual Stars ◽  
White Dwarf Stars ◽  
Binary Evolution ◽  
Insight Into

The origin of the helium-atmosphere DB white dwarfs is still a matter of debate. In particular, the question is unresolved whether binary evolution produces a significant number of DBs. The pulsating DB white dwarfs (DBV stars) offer a complementary insight into this problem through asteroseismology; DBs descending from binaries will have different interior structures than DBs originating from single stars (Nitta & Winget, 1998).GD 358 is by far the best-observed pulsating DBV star, and the only one for which asteroseismology has been performed to date. This star’s structure has been shown to be inconsistent with an origin from binary evolution (Nitta & Winget, 1998), but most of the other DBVs are relatively poorly studied.We therefore analysed archival data on all DBVs and obtained new measurements of stars with very little data available (Table 1), firstly to identify suitable targets for asteroseismological investigations and secondly to examine the pulsation spectra of the DBVs as a group, following the works of Clemens (1994) and Kleinman (1995) on the pulsating DA white dwarfs. Our study also produced new seismological results on individual stars and promising targets for future Whole Earth Telescope (WET, Nather et al., 1990) runs.

The Puzzling Properties of the Helium White Dwarf Orbiting the Millisecond Pulsar PSR J1911-5958A in NGC 6752

2006 ◽  
Vol 641 (2) ◽  
pp. L129-L132 ◽  
Author(s):  
G. Cocozza ◽  
F. R. Ferraro ◽  
A. Possenti ◽  
N. D'Amico
Keyword(s):  
White Dwarf ◽  
Millisecond Pulsar

scholarly journals An Isolated White Dwarf with a 70 s Spin Period

2021 ◽  
Vol 923 (1) ◽  
pp. L6
Author(s):  
Mukremin Kilic ◽  
Alekzander Kosakowski ◽  
Adam G. Moss ◽  
P. Bergeron ◽  
Annamarie A. Conly
Keyword(s):  
White Dwarf ◽  
High Speed ◽  
White Dwarfs ◽  
Tangential Velocity ◽  
Large Mass ◽  
Atmospheric Composition ◽  
Instability Strip ◽  
Detailed Model ◽  
Helium Atmosphere ◽  
Spin Period

Abstract We report the discovery of an isolated white dwarf with a spin period of 70 s. We obtained high-speed photometry of three ultramassive white dwarfs within 100 pc and discovered significant variability in one. SDSS J221141.80+113604.4 is a 1.27 M ⊙ (assuming a CO core) magnetic white dwarf that shows 2.9% brightness variations in the BG40 filter with a 70.32 ± 0.04 s period, becoming the fastest spinning isolated white dwarf currently known. A detailed model atmosphere analysis shows that it has a mixed hydrogen and helium atmosphere with a dipole field strength of B d = 15 MG. Given its large mass, fast rotation, strong magnetic field, unusual atmospheric composition, and relatively large tangential velocity for its cooling age, J2211+1136 displays all of the signatures of a double white dwarf merger remnant. Long-term monitoring of the spin evolution of J2211+1136 and other fast-spinning isolated white dwarfs opens a new discovery space for substellar and planetary mass companions around white dwarfs. In addition, the discovery of such fast rotators outside of the ZZ Ceti instability strip suggests that some should also exist within the strip. Hence, some of the monoperiodic variables found within the instability strip may be fast-spinning white dwarfs impersonating ZZ Ceti pulsators.

scholarly journals A Massive Magnetic Helium Atmosphere White Dwarf Binary in a Young Star Cluster

2019 ◽  
Vol 880 (2) ◽  
pp. 75 ◽  
Author(s):  
Harvey B. Richer ◽  
Ronan Kerr ◽  
Jeremy Heyl ◽  
Ilaria Caiazzo ◽  
Jeffrey Cummings ◽  
...  
Keyword(s):  
White Dwarf ◽  
Young Star ◽  
Star Cluster ◽  
Helium Atmosphere

scholarly journals Whole Earth Telescope observations of the hot helium atmosphere pulsating white dwarf EC 20058−5234

2008 ◽  
Vol 387 (1) ◽  
pp. 137-152 ◽  
Author(s):  
D. J. Sullivan ◽  
T. S. Metcalfe ◽  
D. O'Donoghue ◽  
D. E. Winget ◽  
D. Kilkenny ◽  
...  
Keyword(s):  
White Dwarf ◽  
Helium Atmosphere ◽  
Whole Earth

scholarly journals PSR J1738+0333: the first millisecond pulsar + pulsating white dwarf binary*

2014 ◽  
Vol 446 (1) ◽  
pp. L26-L30 ◽  
Author(s):  
Mukremin Kilic ◽  
J. J. Hermes ◽  
A. Gianninas ◽  
Warren R. Brown
Keyword(s):  
White Dwarf ◽  
Millisecond Pulsar

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 Asteroseismology of GD358 with complex core carbon and oxygen profiles

2015 ◽  
Vol 11 (A29B) ◽  
pp. 489-492
Author(s):  
Agnès Bischoff-Kim ◽  
Judith L. Provencal
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Complete Data ◽  
Time Dependent ◽  
Archival Data ◽  
Data Set ◽  
Helium Atmosphere ◽  
Complex Core ◽  
Pure Helium ◽  
Oxygen Profiles

AbstractGD 358 is the brightest (mv=13.7) and best studied helium atmosphere white dwarf pulsator. We present an analysis based on over 1000 hours of observations spanning 2007-2014 as well as archival data going back to 1982. From the complete data set, we identify a total of 27 independent frequencies and fit 14 of them as m=0 modes in our asteroseismic analysis. We add GD358 to a set of helium atmosphere white dwarfs fitted with similar models. With this consistent set, we can see a trend in the thickness of the pure helium layer that are quantitatively consistent with time-dependent diffusion calculations.

scholarly journals A STRANGE STAR SCENARIO FOR THE FORMATION OF ECCENTRIC MILLISECOND PULSAR/HELIUM WHITE DWARF BINARIES

2015 ◽  
Vol 807 (1) ◽  
pp. 41 ◽  
Author(s):  
Long Jiang ◽  
Xiang-Dong Li ◽  
Jishnu Dey ◽  
Mira Dey
Keyword(s):  
White Dwarf ◽  
Strange Star ◽  
Millisecond Pulsar
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