Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

D. Carollo; D. Koester; A. Spagna; M. G. Lattanzi; S. T. Hodgkin

Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

D. Carollo^*, D. Koester, A. Spagna, M. G. Lattanzi, S. T. Hodgkin

^*Corresponding author for this work

Research output: Contribution to journal › Letter › peer-review

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Abstract

A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UB_JVR_FI_NJHK) and a low resolution spectrum (3500 < λ < 7500 Å) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate T_eff ≃ 5120 ± 200 K and log[C/He] ≃ -5.8 ± 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C₂ to C₂H molecules around T_eff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.

Original language	English
Journal	Astronomy and Astrophysics
Volume	400
Issue number	1
Publication status	Published - Mar 2003

Bibliographical note

Copyright ESO 2003. First published in Astronomy and Astrophysics, Vol. 400, No. 1, published by EDP Sciences. The original publication is available at http://dx.doi.org/10.1051/0004-6361:20030132

Keywords

Stars: Individual: GSC2U J131147.2+292348
Stars: Kinematics
Techniques: Spectroscopic
White dwarfs

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title = "Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348",

abstract = "A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UBJVRFINJHK) and a low resolution spectrum (3500 < λ < 7500 {\AA}) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate Teff ≃ 5120 ± 200 K and log[C/He] ≃ -5.8 ± 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C2 to C2H molecules around Teff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.",

keywords = "Stars: Individual: GSC2U J131147.2+292348, Stars: Kinematics, Techniques: Spectroscopic, White dwarfs",

author = "D. Carollo and D. Koester and A. Spagna and Lattanzi, {M. G.} and Hodgkin, {S. T.}",

note = "Copyright ESO 2003. First published in Astronomy and Astrophysics, Vol. 400, No. 1, published by EDP Sciences. The original publication is available at http://dx.doi.org/10.1051/0004-6361:20030132",

year = "2003",

month = mar,

language = "English",

volume = "400",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

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TY - JOUR

T1 - Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

AU - Carollo, D.

AU - Koester, D.

AU - Spagna, A.

AU - Lattanzi, M. G.

AU - Hodgkin, S. T.

N1 - Copyright ESO 2003. First published in Astronomy and Astrophysics, Vol. 400, No. 1, published by EDP Sciences. The original publication is available at http://dx.doi.org/10.1051/0004-6361:20030132

PY - 2003/3

Y1 - 2003/3

N2 - A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UBJVRFINJHK) and a low resolution spectrum (3500 < λ < 7500 Å) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate Teff ≃ 5120 ± 200 K and log[C/He] ≃ -5.8 ± 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C2 to C2H molecules around Teff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.

AB - A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UBJVRFINJHK) and a low resolution spectrum (3500 < λ < 7500 Å) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate Teff ≃ 5120 ± 200 K and log[C/He] ≃ -5.8 ± 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C2 to C2H molecules around Teff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.

KW - Stars: Individual: GSC2U J131147.2+292348

KW - Stars: Kinematics

KW - Techniques: Spectroscopic

KW - White dwarfs

UR - http://www.scopus.com/inward/record.url?scp=0037335073&partnerID=8YFLogxK

M3 - Letter

AN - SCOPUS:0037335073

VL - 400

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 1

ER -

Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

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