Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey

Harris, Hugh C.; Gates, Evalyn; Gyuk, G.; SubbaRao, Mark; Anderson, Scott F.; Munn, Jeffrey A.; Liebert, James; Knapp, G. R.; Bizyaev, Dmitry; Malanushenko, V. P.; Pan, Kaike; Schneider, Donald P.; Smith, J. Allyn

doi:10.1086/587160

Cited by 37 publications

(68 citation statements)

References 49 publications

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“…Harris et al (2001) and Gates et al (2004) used this feature to identify and confirm six extremely cool white dwarfs, with 18.9 r 19.6, by their unusual SDSS colors. Harris et al (2008) extend this study and present an additional seven cool white dwarfs with 18.7 r 20.4 found in the SDSS by their colors. Rowell et al (2008) in a similar way identified an R F = 17.8 ultracool white dwarf in the SuperCOSMOS Sky Survey ) from its BRI colors.…”

Section: Introductionsupporting

confidence: 60%

“…For example, only three out of the 112 white dwarfs reported by Kilic et al (2006) are detected in Y J H and lie within the LAS DR2 area, and only one of those met our color criteria. Other sources, which are not in our sky area, include those of Gates et al (2004);Hall et al (2008); Rowell et al (2008); and most of the Carollo et al (2006) and Harris et al (2008) sources. Those with inappropriate colors include the Harris et al (2001) source that is not detected at J or H; two Carollo et al sources; and two sources from Harris et al (2008), one of which is not detected at H and the other of which has J − H > 0.…”

Section: Sample Selectionmentioning

confidence: 91%

“…Other sources, which are not in our sky area, include those of Gates et al (2004);Hall et al (2008); Rowell et al (2008); and most of the Carollo et al (2006) and Harris et al (2008) sources. Those with inappropriate colors include the Harris et al (2001) source that is not detected at J or H; two Carollo et al sources; and two sources from Harris et al (2008), one of which is not detected at H and the other of which has J − H > 0. Of the 13 faint disk and halo candidates identified by Vidrih et al (2007) that are detected at all of Y J H , only one has J − H < −0.1, and that is the Kilic et al white dwarf recovered in our search.…”

Section: Sample Selectionmentioning

confidence: 91%

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Cool White Dwarfs Identified in the Second Data Release of the Ukirt Infrared Deep Sky Survey

Lodieu

Leggett

Bergeron

et al. 2009

ApJ

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We have paired the second data release of the Large Area Survey of the UKIRT Infrared Deep Sky Survey with the fifth data release of the Sloan Digital Sky Survey to identify 10 cool white dwarf candidates, from their photometry and astrometry. Of these 10, one was previously known to be a very cool white dwarf. We have obtained optical spectroscopy for seven of the candidates using the GMOS-N spectrograph on Gemini North, and have confirmed all seven as white dwarfs. Our photometry and astrometry indicate that the remaining two objects are also white dwarfs. The model analysis of the photometry and available spectroscopy shows that the seven confirmed new white dwarfs, and the two new likely white dwarfs, have effective temperatures in the range of T eff = 5400-6600 K. Our analysis of the previously known white dwarf confirms that it is cool, with T eff = 3800 K. The cooling age for this dwarf is 8.7 Gyr, while that for the nine ∼ 6000 K white dwarfs is 1.8-3.6 Gyr. We are unable to determine the masses of the white dwarfs from the existing data, and therefore we cannot constrain the total ages of the white dwarfs. The large cooling age for the coolest white dwarf in the sample, combined with its low estimated tangential velocity, suggests that it is an old member of the thin disk, or a member of the thick disk of the Galaxy, with an age of 10-11 Gyr. The warmer white dwarfs appear to have velocities typical of the thick disk or even halo; these may be very old remnants of low-mass stars, or they may be relatively young thin-disk objects with unusually high space motion.

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Section: Introductionsupporting

confidence: 60%

Section: Sample Selectionmentioning

confidence: 91%

Section: Sample Selectionmentioning

confidence: 91%

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Cool White Dwarfs Identified in the Second Data Release of the Ukirt Infrared Deep Sky Survey

Lodieu

Leggett

Bergeron

et al. 2009

ApJ

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“…A number of so-called ultra-cool white dwarfs (T eff < 4000 K) that show flux depression in the IR due to hydrogen molecule absorption have been detected so far [3]. However, it is believed that most or all of these ultra-cool white dwarfs are low-mass products of binary evolution and thus not representative for the oldest white dwarfs.…”

Section: Introductionmentioning

confidence: 99%

The WFCAM transit survey and cool white dwarfs

Catalán

Napiwotzki

Hodgkin

et al. 2013

EPJ Web of Conferences

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Abstract. We present results from our search for cool white dwarfs in the WTS (WFCAM Transit Survey). Repeat observations starting in 2007 allowed to produce deep stacked images in J and measure proper motions. We combine this with deep optical imaging to select cool white dwarf candidates (T eff < 5000 K). About 27 cool white dwarf candidates with proper motions above 0.10 arcsec/yr were identified in one of the fields representing 1/8th of the survey area. Follow-up spectroscopy with the 10.2 m GTC telescope at La Palma confirmed the white dwarf status for all observed candidates. On-going work is being carried out to increase the sample of cool white dwarfs that will allow a more comprehensive study of the thick disk/halo white dwarf population.

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“…Measuring the position of this minimum, we can measure the age of the galactic disk itself (D'Antona & Mazzitelli 1978;Harris et al 2006, and references therein). Presently, the number of known ultra-cool WDs is about 20 (Harris et al 2008) and most of them were discovered in the Sloan Digital Sky Survey.…”

Section: Introductionmentioning

confidence: 99%

White dwarfs in the Capodimonte deep field

Silvotti

Catalán

Cignoni

et al. 2008

A&A

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Aims. In this article we describe the search for white dwarfs (WDs) in the multi-band photometric data of the Capodimonte deep field survey. Methods. The WD candidates were selected through the V − R C vs. B − V color-color diagram. For two bright objects, the WD nature has been confirmed spectroscopically, and the atmospheric parameters (T eff and log g) have been determined. We have computed synthetic stellar population models for the observed field and the expected number of white dwarfs agrees with the observations. The possible contamination by turn-off and horizontal branch halo stars has been estimated. The quasar (QSO) contamination has been determined by comparing the number of WD candidates in different color bins with state-of-the-art models and previous observations. Results. The WD space density is measured at different distances from the Sun. The total contamination (non-degenerate stars + QSOs) in our sample is estimated to be around 30%. This work should be considered a small experiment in view of more ambitious projects to be performed in the coming years in larger survey contexts.

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Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey

Cited by 37 publications

References 49 publications

Cool White Dwarfs Identified in the Second Data Release of the Ukirt Infrared Deep Sky Survey

Cool White Dwarfs Identified in the Second Data Release of the Ukirt Infrared Deep Sky Survey

The WFCAM transit survey and cool white dwarfs

White dwarfs in the Capodimonte deep field

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