Planet GJ 229 Ba

Detailed information about planet GJ 229 Ba and its parameters.

Planet parameters Publications Observability Predictor

Planet

Name

GJ 229 Ba

Planet Status

Confirmed

Discovered in

1995

Update

2024-10-22

Mass

38.1 (\pm 1.0)

M_J 3 publications

The cool brown dwarf Gliese 229 B is a close binary
3D Selection of 167 Substellar Companions to Nearby Stars
Discovery of a cool brown dwarf

Mass*sin(i)

1.61971 (\pm 0.664)

M_J 1 publication

Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

Semi-Major Axis

28.933 (\pm 1.0)

AU 2 publications

3D Selection of 167 Substellar Companions to Nearby Stars
Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

Orbital Period

79231.9 (\begin{matrix} + 3873.1 \\ - 3781.1 \end{matrix})

day 2 publications

3D Selection of 167 Substellar Companions to Nearby Stars
Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

Eccentricity

0.853 (\pm 0.002)

3D Selection of 167 Substellar Companions to Nearby Stars
Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

ω

358.285 (\begin{matrix} + 0.836 \\ - 0.846 \end{matrix})

deg 2 publications

3D Selection of 167 Substellar Companions to Nearby Stars
Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

T_peri

—

Radius

0.92

R_J 2 publications

Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B
GJ 229B: Solving the Puzzle of the First Known T Dwarf with the APOLLO Retrieval Code

Inclination

5.497 (\begin{matrix} + 0.153 \\ - 0.162 \end{matrix})

deg 1 publication

3D Selection of 167 Substellar Companions to Nearby Stars

Detection Method

Imaging

Mass Meas. Method

Astrometry

Radius Meas. Method

Flux

Primary transit

—

Secondary transit

—

λ

—

Impact Parameter b

—

Time V_r=0

—

Velocity Semiamplitude K

81.674 (\begin{matrix} + 1.688 \\ - 1.68 \end{matrix})

m/s 2 publications

3D Selection of 167 Substellar Companions to Nearby Stars
Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs

Calculated temperature

860.0 (\pm 20.0)

K 2 publications

The cool brown dwarf Gliese 229 B is a close binary
Discovery of a cool brown dwarf

Measured temperature

— 1 publication

GJ 229B: Solving the Puzzle of the First Known T Dwarf with the APOLLO Retrieval Code

Hottest point longitude

—

Geometric albedo

—

Surface gravity log(g/g_H)

—

Alternate Names

Gliese 229 b, HD 42581 b

Data Source	Type	Result Value	Result Figure	Notes	Reference

Molecule	Data Source	Type	Result Value	Result Figure	Notes	Reference
CH4
CH4	Modeling	Detected	$-3.352 (\begin{matrix} + 0.018 \\ - 0.017 \end{matrix})$			2022 - HOWE A.R.
CO
CO	Modeling	Detected	$-3.805 (\begin{matrix} + 0.11 \\ - 0.113 \end{matrix})$			2022 - HOWE A.R.
CO2
CO2	Modeling	Detected	$-7.9 (\begin{matrix} + 2.6 \\ - 2.7 \end{matrix})$			2022 - HOWE A.R.
H2O
H2O	Modeling	Detected	$-3.43 (\begin{matrix} + 0.017 \\ - 0.016 \end{matrix})$			2022 - HOWE A.R.
H2S
H2S	Modeling	Detected	$-5.6 (\begin{matrix} + 0.9 \\ - 4.5 \end{matrix})$			2022 - HOWE A.R.
K
K	Modeling	Detected	$-5.942 (\begin{matrix} + 0.11 \\ - 0.014 \end{matrix})$			2022 - HOWE A.R.
Na
Na	Modeling	Detected	$-5.942 (\begin{matrix} + 0.11 \\ - 0.014 \end{matrix})$			2022 - HOWE A.R.
NH3
NH3	Modeling	Detected	$-4.504 (\begin{matrix} + 0.021 \\ - 0.024 \end{matrix})$			2022 - HOWE A.R.

Feng et al. (2022) list GJ 229 B as "HD 42581 d" following separation order of substellar components. However the more correct designation is "HD 42581 b" according to the chronology of discoveries (1995).
Howe et al. (2022) provide a lower mass estimate (41.6 ± 3.3 M_Jup for an age > 1 Gyr).
17 Oct. 2024: Brandt et al. (2021) estimated a mass of 71.4 ± 0.6M_Jup for GJ 229 B also considering a binary nature for the object. Kawashima et al. (2024) provide support to the binary model. Accordingly taking 71.4 ± 0.6M_Jup as total mass and 1.3 R_Jup as total radius, GJ 229 B is likely an equal-mass substellar binary of about 36 M_Jup and 0.92 R_Jup for each component (for M_b = M_s/2 and R_b = R_s/ √ 2, where M_b and M_s are namely the mass estimate for a binary and a single object as well as R_b and R_s concern the radius estimate for a binary and a single object).
18 Oct. 2024: Gj 229 B is confirmed as binary brown dwarf with individual spectral types close to T7 and T8 respectively.

No link

Star

Name

GJ 229

Distance

5.75624 (\pm 0.001525)

pc 1 publication

The Revised TESS Input Catalog and Candidate Target List

Spectral type

M1V

Apparent magnitude V

8.125

Mass

0.544 (\pm 0.041)

M_Sun 2 publications

Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs
The Revised TESS Input Catalog and Candidate Target List

Age

2.45 (\pm 0.2)

Gyr 1 publication

The cool brown dwarf Gliese 229 B is a close binary

Effective temperature

3564.0 K 1 publication

Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics

Radius

0.548 (\pm 0.043)

R_Sun 1 publication

The Revised TESS Input Catalog and Candidate Target List

Metallicity [Fe/H]

—

Detected Disc

—

Magnetic Field

—

RA₂₀₀₀

06:10:34.6

Dec₂₀₀₀

-21:51:52.7

Alternate Names

HD 42581, NAJ 1

No remarks

No link

Simbad
Most recent references (ADS)