CFBDSIR J145829+101343 explained

CFBDSIR J145829+101343 (designation abbreviated to CFBDSIR 1458+10, or CFBDSIR J1458+1013) is a binary system of two brown dwarfs of spectral classes T9 + Y0 orbiting each other, located in constellation Boötes about 104 light-years away from Earth.

The smaller companion, CFBDSIR 1458+10B, has a surface temperature of approx 370 K (≈100 °C). It used to be known as the coolest known brown dwarf until the discovery of WISE 1828+2650 in August 2011.

Discovery

CFBDSIR 1458+10 A was discovered in 2010 by Delorme et al. from the Canada-France Brown Dwarf Survey using the facilities MegaCam and mounted on the 3.6 m Canada-France-Hawaii Telescope, located on Mauna Kea Observatory, Hawaii. Image in z` band was taken on 2004 July 15 with MegaCam, and image in J band was taken on 2007 April 1 with WIRCam. In 2009 they made follow-up photometry, using the SOFI near infrared camera at the ESO 3.5 m New Technology Telescope (NTT) at the La Silla Observatory, Chile. In 2010 Delorme et al. published a paper in Astronomy and Astrophysics where they reported the identification of 55 T-dwarfs candidates, six of which were photometrically confirmed as T-dwarfs, including 3 ultracool brown dwarfs (later than T7 dwarfs and possible Y dwarfs), including CFBDSIR 1458+10.[1]

Discovery of B

CFBDSIR 1458+10 B was discovered in 2011 by Liu et al. with laser guide star (LGS) adaptive optics (AO) system of the 10 m Keck II Telescope on Mauna Kea, Hawaii, using infra-red camera NIRC2 (the observations were made on 2010 May 22 and 2010 July 8 (UT)). In 2011 Liu et al. published a paper in The Astrophysical Journal where they presented discovery of CFBDSIR 1458+10 system component B (the only discovery presented in the article). Also they presented a near-infrared (J-band) trigonometric parallax of the system, measured using WIRCam on the Canada-France-Hawaii Telescope (CFHT), Mauna Kea, in seven epochs during the 2009–2010; and spectroscopy with the X-Shooter spectrograph at the European Southern Observatory's Very Large Telescope (VLT) Unit Telescope 2 (UT2) in Chile (the observations have been performed from May 5 to July 9, 2010), that allowed to calculate the temperature (and other physical parameters) of the two brown dwarfs.

2012 Keck LGS-AO imaging

In 2012 CFBDSIR 1458+10 system was observed by Liu et al. with laser guide star (LGS) adaptive optics (AO) system of the 10 m Keck II Telescope on Mauna Kea, Hawaii, using infra-red camera NIRC2 (the observations were made on 2012 April 13 (UT)). In 2012 Liu et al. published a paper in The Astrophysical Journal where they presented results of observations with Keck II LGS-AO of three brown dwarf binary systems, binarity of the two of which was first presented in this paper, and binarity of the other one, CFBDSIR 1458+10, was known before.

Distance

Trigonometric parallax of CFBDSIR 1458+10, measured under The Hawaii Infrared Parallax Program by Dupuy & Liu in 2012, is 31.3 ± 2.5 mas, corresponding to a distance 31.9 pc, or 104.2 ly.

CFBDSIR 1458+10 distance estimates

Source Ref.
Delorme et al. (2010) ~23 ~75
Liu et al. (2011) 43.3 ± 4.5 23.1 ± 2.4 75.3 ± 7.8
Dupuy & Liu (2012)
34.0 ± 2.6 29.4 95.9
Dupuy & Liu (2012) 31.3 ± 2.5 31.9 104.2

Space motion

CFBDSIR 1458+10 has proper motion of about 420 milliarcseconds per year.

CFBDSIR 1458+10 proper motion estimates

Source Ref.
Delorme et al. (2010) 444 ± 16 157.5 ± 2.1 170 ± 16 −410 ± 16
Liu et al. (2011) 432 ± 6 154.2 ± 0.7 188 −389
Dupuy & Liu (2012)
418.1 ± 3.2 155.4 ± 0.4 174.3 ± 3.0 −380.0 ± 3.2
Dupuy & Liu (2012) 419.6 ± 2.6 155.50 ± 0.28 174.0 ± 2.0 −381.8 ± 2.7

Physical properties

Using three models, Liu et al. calculated physical properties of CFBDSIR 1458+10 components.

From Lyon/COND models and Lbol:

Component and
assumed age
log g,
cm/s2
P,
yr
A (for 1 Gyr) 12.1 ± 1.9 556 ± 48 4.45 ± 0.07
B (for 1 Gyr) 5.8 ± 1.3 360 ± 40 4.10 ± 0.10 35
A (for 5 Gyr) 31 ± 4 605 ± 55 5.00 ± 0.08
B (for 5 Gyr) 14 ± 3 380 ± 50 4.58 ± 0.11 22

From Burrows et al. (1997) models and Lbol):

Component and
assumed age
log g,
cm/s2
P,
yr
A (for 1 Gyr) 13 ± 2 550 ± 50 4.47 ± 0.07
B (for 1 Gyr) 6.8 ± 1.5 350 ± 40 4.14 ± 0.10 33
A (for 5 Gyr) 36 ± 4 600 ± 60 5.06 ± 0.07
B (for 5 Gyr) 17 ± 4 380 ± 50 4.65 ± 0.12 20

From Burrows et al. (2003) models and M(J):

Component and
assumed age
log g,
cm/s2
P,
yr
A (for 1 Gyr) 11.1 ± 0.7 479 ± 20 4.37 ± 0.03
B (for 1 Gyr) 7.6 ± 0.6 386 ± 15 4.19 ± 0.04 34
A (for 5 Gyr) >25 >483 >4.85
B (for 5 Gyr) 18.8 ± 1.3 407 ± 15 4.69 ± 0.03 <22

The adopted surface temperature of B is 370 ± 40 K, and adopted mass is 6-15 MJup.

Luminosity

At the time of its discovery, CFBDSIR 1458+10 B was the least luminous brown dwarf known.

CFBDSIR 1458+10 bolometric luminosity estimates

Source Lbol/L (A) Lbol/L (B) Ref.
Liu et al. (2011) 10−6.02 ± 0.14
((1.1 ± 0.4) × 10−6)
10−6.74 ± 0.19
((2.0 ± 0.9) × 10−7)
Liu et al. (2012) 10−5.72 ± 0.13 10−6.53 ± 0.13

B's spectral class

In Liu et al. (2011) CFBDSIR 1458+10 B was assigned to the spectral class >T10, it was proposed that CFBDSIR 1458+10 B may be a member of the Y spectral class of brown dwarfs. In 2012 Liu et al. assigned it a spectral class Y0.

Water clouds

Due to the low surface temperature for a brown dwarf, CFBDSIR 1458+10 B may be able to form water clouds in its upper atmosphere.

See also

The other two brown dwarf binary systems, observed by Liu et al. with Keck II LGS-AO in 2012:

External links

Notes and References

  1. The other two ultracool brown dwarfs are CFBDSIR221903.07+002417.92 and CFBDSIR221505.06+003053.11. Three earlier type confirmed T dwarfs, as well as 49 unconfirmed candidates, are not listed in the article. (However, it is mentioned that two of three earlier type confirmed T dwarfs are re-identifications of already spectroscopically confirmed CFBDS brown dwarfs).