He-rich white dwarfs: Birth-rate and kinematics of different groups of white dwarfs

Guseinov, O. H.; Novruzova, H. I.; Rustamov, Yu. S.

doi:10.1007/bf00653488

Cited by 19 publications

(5 citation statements)

References 41 publications

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“…We therefore expect high-mass disk white dwarfs to have a low velocity dispersion in comparison to low-mass disk white dwarfs whose progenitors formed earlier. This connection was suggested in Guseinov, Novruzova & Rustamov (1983) who performed an analysis suggesting that white dwarfs with larger masses have smaller dispersions, however this was reinvestigated by Sion et al (1988) with a larger sample of 78 DA white dwarfs where no evidence for any correlation was found. This paper readdresses the connection between mass and kinematics with a greatly increased sample size.…”

Section: Introductionmentioning

confidence: 99%

White dwarf kinematics versus mass

Wegg

Phinney

2012

Monthly Notices of the Royal Astronomical Society

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We investigated the relationship between the kinematics and mass of young (<3 × 108 yr) white dwarfs using proper motions. Our sample is taken from the colour‐selected catalogues of the Sloan Digital Sky Survey and the Palomar–Green Survey, both of which have spectroscopic temperature and gravity determinations. We find that the dispersion decreases with increasing white dwarf mass. This can be explained as a result of less scattering by objects in the Galactic disc during the shorter lifetime of their more massive progenitors. A direct result of this is that white dwarfs with high mass have a reduced scale height, and hence their local density is enhanced over their less massive counterparts. In addition, we have investigated whether the kinematics of the highest mass white dwarfs (>0.95 M⊙) are consistent with the expected relative contributions of single star evolution and mergers. We find that the kinematics are consistent with the majority of high‐mass white dwarfs being formed through single star evolution.

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Section: Introductionmentioning

confidence: 99%

White dwarf kinematics versus mass

Wegg

Phinney

2012

Monthly Notices of the Royal Astronomical Society

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“…Ferrario et al 1997a ; (8) Burleigh et al 1999 ; (9) Green & Liebert 1981 ; (10) Schmidt et al 1990 ; (11) Schmidt et al 1996a ; (12) Jordan et al 1998 ; (13) Angel et al 1985 ; (14) (15) (16) Jordan 1992a ; (17) Guseinov et al 1983 ;(18)Putney & Jordan 1995 ; 19) Putney 1997 ; (20) Angel 1978 ; (21) Reimers et al 1996 ; (22) Cohen et al 1993 ; (23) Bues 1999 ; (24) Wickramasinghe & Bessell 1979 ; (25) Schmidt et al 1999a ; (26) Schmidt & Norsworthy 1991 ; (27) Wickramasinghe & Cropper 1988 ; (28) Jordan 1997 ; (29) Sa †er et al 1989 ; (30) Wickramasinghe & Bessell 1976 ; (31) Wickramasinghe & Martin 1979a ; (32) Greenstein & Oke 1982 ; (33) Martin & Wickramasinghe 1986 ; (34) Achilleos et al 1992a ; (35) Reimers et al 1994 ; (36) Liebert et al 1985 ; (37) Achilleos & Wickramasinghe 1989 ; (38) Foltz et al 1989 ; (39) Reimers et al 1998 ; (40) Dreizler et al 1994 ; (41) Jordan 1989 ; (42) Schmidt & Smith 1995 ; (43) Bergeron et al 1997 ; (44) Friedrich et al 1997 ; (45) Bergeron et al 1992a ; (46) Vennes 1999 ; (47) Vennes et al 1999a ; (48) Putney 1995 ; (49) Greenstein & McCarthy 1985 ; (50) Ferrario et al 1997b ; (51) Wegner et al 1987 ; (52) Jordan 1992b ; (53) Reimers et al 1998 ; (54) Angel 1977 ; (55)Achilleos et al 1991 ; (56) Angel et al 1974 ; (57) Bergeron et al 1993 ; (58) Liebert et al 1983 ; (59) Schmidt et al 1992a ; (60) Ferrario et al 1998 ; (61) Greenstein 1986 ; (62) Moran et al 1998 ; (63) Kanaan et al 1999 ; (64) Reid 1996 ; (65) Schmidt et al 1992b ; (66) Wesemael et al 1995 ; (67) Maxted et al 2000 ; (68) Schmidt & Smith 1994 ; (69) Angel et al 1981 ; (70) Friedrich et al 1996a ; (71) Ruiz & Maza 1988 ; (72) Schmidt et al 1995 ; (73) Reimers et al 1998 ; (74) Schmidt et al 1998 ; (75) Bragaglia et al 1995. …”

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Magnetism in Isolated and Binary White Dwarfs

Wickramasinghe

Ferrario

2000

PUBL ASTRON SOC PAC

367

342

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ABSTRACT. Since the discovery of the Ðrst isolated magnetic white dwarf (MWD) Grw ]70¡8047 nearly 60 years ago, the number of stars belonging to this class has grown steadily. There are now some 65 isolated white dwarfs classiÐed as magnetic, and a roughly equal number of MWDs are found in the close interacting binaries known as the magnetic cataclysmic variables (MCVs). The isolated MWDs comprise D5% of all WDs, while the MCVs comprise D25% of all CVs. The magnetic Ðelds range from D3 ] 104È109 G in the former group with a distribution peaking at 1.6 ] 107 G, and D107È3 ] 108 G in the latter group. The space density of isolated magnetic white dwarfs with Ðelds in the range D3 ] 104È109 G is estimated to be D1.5 ] 10~4 pc~3. The MCVs have a space density that is about a hundred times smaller.About 80% of the isolated MWDs have almost pure H atmospheres and show only hydrogen lines in their spectra (the magnetic DAs), while the remainder show He I lines (the magnetic DBs) or molecular bands of and CH (magnetic DQs) and have helium as the dominant atmospheric constituent, mirroring the C 2 situation in the nonmagnetic white dwarfs. The incidence of stars of mixed composition (H and He) appears to be higher among the MWDs.There is growing evidence based on trigonometric parallaxes, space motions, and spectroscopic analyses that the isolated MWDs tend as a class to have a higher mass than the nonmagnetic white dwarfs. The mean mass for 16 MWDs with well-constrained masses is Magnetic Ðelds may therefore play a Z0.95 M _ . signiÐcant role in angular momentum and mass loss in the postÈmain-sequence phases of single star evolution a †ecting the initial-Ðnal mass relationship, a view supported by recent work on cluster MWDs. The progenitors of the vast majority of the isolated MWDs are likely to be the magnetic Ap and Bp stars. However, the discovery of two MWDs with masses within a few percent of the Chandrasekhar limit, one of which is also rapidly rotating minutes), has led to the proposal that these may be the result of (P spin \ 12 double-degenerate (DD) mergers. An intriguing possibility is that magnetism, through its e †ect on the initial-Ðnal mass relationship, may also favor the formation of more massive double degenerates in close binary evolution. The magnetic DDs may therefore be more likely progenitors of Type Ia supernovae.A subclass of the isolated MWDs appear to rotate slowly with no evidence of spectral or polarimetric variability over periods of tens of years, while others exhibit rapid rotation with coherent periods in the range of tens of minutes to hours or days. There is a strong suggestion of a bimodal period distribution. The "" rapidly ÏÏ rotating isolated MWDs may include as a subclass stars which have been spun up during a DD merger or a previous phase of mass transfer from a companion star.Zeeman spectroscopy and polarimetry, and cyclotron spectroscopy, have variously been used to estimate magnetic Ðelds of the isolated MWDs and the MWDs in MCVs and to place strong constraints on the Ðeld str...

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“…The birth rate of He-dominated WDs is ∼1.5 × 10 −12 pc −3 yr −1 (Guseinov et al 1983), which means that within 100 pc radius only one WD is formed in approximately 10 6 yr. Hence, continuous GWs from some massive WDs, which have radiation timescales (life span) ∼ 10 8−9 yr, can be detected, as shown in Figures 4 and 8.…”

Section: Discussionmentioning

confidence: 98%

Gravitational Wave in f(R) Gravity: Possible Signature of Sub- and Super-Chandrasekhar Limiting-mass White Dwarfs

Kalita

Mukhopadhyay

2021

ApJ

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After the prediction of many sub-and super-Chandrasekhar (at least a dozen for the latter) limiting-mass white dwarfs (WDs), hence apparently a peculiar class of WDs, from the observations of luminosity of Type Ia supernovae, researchers have proposed various models to explain these two classes of WD separately. We earlier showed that these two peculiar classes of WD, along with the regular WD, can be explained by a single form of the f (R) gravity, whose effect is significant only in the high-density regime, and it almost vanishes in the low-density regime. However, since there is no direct detection of such a WD, it is difficult to single out one specific theory from the zoo of modified theories of gravity. We discuss the possibility of direct detection of such a WD in gravitational wave (GW) astronomy. It is well known that in f (R) gravity more than two polarization modes are present. We estimate the amplitudes of all the relevant modes for the peculiar and the regular WD. We further discuss the possibility of their detections through future-based GW detectors, such as LISA, ALIA, DECIGO, BBO, or the Einstein Telescope, and thereby put constraints on or rule out various modified theories of gravity. This exploration links the theory with possible observations through GW in f (R) gravity.

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He-rich white dwarfs: Birth-rate and kinematics of different groups of white dwarfs

Cited by 19 publications

References 41 publications

White dwarf kinematics versus mass

White dwarf kinematics versus mass

Magnetism in Isolated and Binary White Dwarfs

Gravitational Wave in f(R) Gravity: Possible Signature of Sub- and Super-Chandrasekhar Limiting-mass White Dwarfs

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