On the parallax of WD 0346+246: a halo white dwarf candidate

Hambly, N. C.; Smartt, S. J.; Hodgkin, S. T.; Jameson, R. F.; Kemp, S. N.; Rolleston, W. R. J.; Steele, I. A.

doi:10.1046/j.1365-8711.1999.03085.x

Cited by 27 publications

(28 citation statements)

References 19 publications

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“…Therefore WD0346+246 does not have a high mass (like ESO439-26 25 ) and is probably a`normal', albeit unusually cool, white dwarf. The location of WD0346+246 on the white-dwarf sequence in the M V , V±I diagram also supports this argument 21 . Estimating the age of WD0346+246 is dif®cult, as we lack important information concerning the atmosphere and core composition.…”

supporting

confidence: 63%

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Infrared spectrum of an extremely cool white-dwarf star

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Hambly

et al. 2000

Nature

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White dwarfs are the remnant cores of stars that initially had masses of less than 8 solar masses. They cool gradually over billions of years, and have been suggested to make up much of the 'dark matter' in the halo of the Milky Way. But extremely cool white dwarfs have proved difficult to detect, owing to both their faintness and their anticipated similarity in colour to other classes of dwarf stars. Recent improved models indicate that white dwarfs are much more blue than previously supposed, suggesting that the earlier searches may have been looking for the wrong kinds of objects. Here we report an infrared spectrum of an extremely cool white dwarf that is consistent with the new models. We determine the star's temperature to be 3,500 +/- 200 K, making it the coolest known white dwarf. The kinematics of this star indicate that it is in the halo of the Milky Way, and the density of such objects implied by the serendipitous discovery of this star is consistent with white dwarfs dominating the dark matter in the halo.

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confidence: 63%

“…Using the distance to WD0346+246 given in ref. 21, we ®nd L 7:6 6 2:3 3 10 28 erg s 2 1 , or L 2:0 6 0:6 3 10 2 5 L ( , and r 0:012 6 0:002R ( (here L ( and R ( are the solar luminosity and radius, respectively). The models 24 indicate a mass of 0:65 6 0:15M ( .…”

mentioning

confidence: 98%

Infrared spectrum of an extremely cool white-dwarf star

Hodgkin

Oppenheimer

Hambly

et al. 2000

Nature

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“…Hambly et al (1999), Dahn et al (2002), Tinney et al (2003), and Vrba et al (2004) have reported a total of one, one, two, and five first trigonometric parallaxes for MOTION systems, respectively. All of those studies concentrated on the (very) cool end of the main sequence, L or T dwarfs, or in a single case, a white dwarf.…”

Section: Discussionmentioning

confidence: 98%

The Solar Neighborhood. XIII. Parallax Results from the CTIOPI 0.9 Meter Program: Stars with μ ≥ 1."0 yr^-1(MOTION Sample)

et al. 2005

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We present the first set of definitive trigonometric parallaxes and proper motions from the Cerro Tololo InterAmerican Observatory Parallax Investigation. Full astrometric reductions for the program are discussed, including methods of reference star selection, differential color refraction corrections, and conversion of relative to absolute parallax. Using data acquired at the 0.9 m telescope at CTIO, full astrometric solutions and VRIJHK s photometry are presented for 36 red and white dwarf stellar systems with proper motions faster than 1B0 yr À1 . Of these, 33 systems have their first ever trigonometric parallaxes, which comprise 41% of MOTION systems (those reported to have proper motions greater than 1B0 yr À1 ) south of ¼ 0 that have no parallaxes. Four of the systems are new members of the RECONS 10 pc sample for which the first accurate trigonometric parallaxes are published here: DENIS J1048À3956 (4:04 AE 0:03 pc), GJ 1128 (LHS 271, 6:53 AE 0:10 pc), GJ 1068 (LHS 22, 6:97 AE 0:09 pc), and GJ 1123 (LHS 263, 9:02 AE 0:16 pc). In addition, two red subdwarf-white dwarf pairs, LHS 193AB and LHS 300AB, are identified. The white dwarf secondaries fall in a previously uncharted region of the H-R diagram.

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“…The challenge is the need for a largescale parallax survey focusing on WDs to confirm proximity. Since the Hipparcos mission, only six WD trigonometric parallaxes have been published (Hambly et al 1999;Smart et al 2003), and of those, only two are within 25 pc. The USNO parallax program is in the process of publishing trigonometric parallaxes for $130 WDs, mostly in the northern hemisphere, although proximity was not a primary motivation for target selection (C. Dahn 2004, private communication).…”

Section: Discussionmentioning

confidence: 99%

The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems

et al. 2007

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We present spectra for 33 previously unclassified white dwarf systems brighter than V ¼ 17, primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect that three of these systems are unresolved double degenerates. We obtained VRI photometry for these 33 objects, as well as for 23 known white dwarf systems without trigonometric parallaxes, also primarily in the southern hemisphere. For the 56 objects, we converted the photometry values to fluxes and fit them to a spectral energy distribution using the spectroscopy to determine which model to use (i.e., pure hydrogen, pure helium, or metal-rich helium), resulting in estimates of T eA and distance. Eight of the new and 12 of the known systems are estimated to be within the NStars and Catalogue of Nearby Stars horizons of 25 pc, constituting a potential 18% increase in the nearby white dwarf sample. Trigonometric parallax determinations are under way via CTIOPI for these 20 systems. One of the DCs is cool, so it displays absorption in the near-infrared. Using the distance determined via trigonometric parallax, we are able to constrain the model-dependent physical parameters and find that this object is most likely a mixed H /He atmosphere white dwarf similar to other cool white dwarfs identified in recent years with significant absorption in the infrared due to collision-induced absorptions by molecular hydrogen.

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On the parallax of WD 0346+246: a halo white dwarf candidate

Cited by 27 publications

References 19 publications

Infrared spectrum of an extremely cool white-dwarf star

Infrared spectrum of an extremely cool white-dwarf star

The Solar Neighborhood. XIII. Parallax Results from the CTIOPI 0.9 Meter Program: Stars with μ ≥ 1."0 yr^-1(MOTION Sample)

The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems

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On the parallax of WD 0346+246: a halo white dwarf candidate

Cited by 27 publications

References 19 publications

Infrared spectrum of an extremely cool white-dwarf star

Infrared spectrum of an extremely cool white-dwarf star

The Solar Neighborhood. XIII. Parallax Results from the CTIOPI 0.9 Meter Program: Stars with μ ≥ 1."0 yr-1(MOTION Sample)

The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems

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The Solar Neighborhood. XIII. Parallax Results from the CTIOPI 0.9 Meter Program: Stars with μ ≥ 1."0 yr^-1(MOTION Sample)