HD 98649

HD 98649
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Crater
Right ascension	11h 20m 51.769s
Declination	–23° 13′ 02.43″
Apparent magnitude (V)	+8.00
Characteristics
Spectral type	G4V
B−V color index	+0.658 ± 0.003
Astrometry
Proper motion (μ)	RA: –199.28 ± 0.57 mas/yr ; Dec.: –177.51 ± 0.48 mas/yr
Parallax (π)	23.6832 ± 0.0489 mas
Distance	137.7 ± 0.3 ly ; (42.22 ± 0.09 pc)
Absolute magnitude (MV)	+4.91
Details
Mass	0.97 ± 0.02 M☉
Radius	~1 R☉
Luminosity (bolometric)	0.86 L☉
Luminosity (visual, LV)	0.83 L☉
Surface gravity (log g)	4.38 ± 0.08 cgs
Temperature	5759 ± 35 K
Metallicity [Fe/H]	–0.02 ± 0.03 dex
Rotation	27 ± 4.0 days
Rotational velocity (v sin i)	1.19 km/s
Age	2.3 ± 2.0 Gyr
Other designations
	BD−22° 3121, HIP 55409, SAO 179793, LTT 4199
Database references
SIMBAD	data
Exoplanet Archive	data
Extrasolar Planets; Encyclopaedia	data

HD 98649 is a G-type yellow dwarf star, classified as a G4V, that has approximately the same mass and diameter as the Sun, but has only 86% of its luminosity. It is considered a solar analog.^[4] HD 98649 is about 138 light-years from earth. HD 98649 is found in the Crater constellation.^[2]

Planetary system[]

From 1998 to 2012, the star was under observance from "the CORALIE echelle spectrograph at La Silla Observatory".

In 2012, a long-period, wide-orbiting planet was deduced by radial velocity. This was published in November.

The discoverers noted, "HD 98649b is in the top five of the most eccentric planetary orbit and the most eccentric planet known with a period larger than 600 days." The reason for this eccentricity is unknown. They also submit it as a "candidate for direct imaging", once it gets out to "10.4 AU at apoastron" and 250 milliarcseconds of separation relative to Earth.^[2]

Using astrometry from Gaia, astronomers were able to deduce the true mass of HD 98649 b as 9.7 M_J, somewhat higher than its minimum mass from radial velocity.^[4]

The HD 98649 planetary system^[4]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	9.7+2.3 −1.9 M_J	5.97+0.24 −0.21	14.74+0.88 −0.75	0.852^+0.033 _−0.022	—	—

Sun comparison[]

Chart compares the Sun to HD 98649.

Identifier	J2000 Coordinates		Distance (ly)	Stellar Class	Temperature (K)	Metallicity (dex)	Age (Gyr)	Notes
Identifier	Right ascension	Declination	Distance (ly)	Stellar Class	Temperature (K)	Metallicity (dex)	Age (Gyr)	Notes
Sun	—	—	0.00	G2V	5,778	+0.00	4.6	^[5]
HD 98649 ^[6]	11^h 20^m 51.769^s	–23° 13′ 02″	135	G4V	5,770	−0.02	2.3

References[]

^ ^a ^b ^c ^d ^e van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b ^c ^d Li, Yiting; Brandt, Timothy D.; Brandt, G. Mirek; Dupuy, Trent J.; Michalik, Daniel; Jensen-Clem, Rebecca; Zeng, Yunlin; Faherty, Jacqueline; Mitra, Elena L. (2021). "Precise Masses and Orbits for Nine Radial-velocity Exoplanets". The Astronomical Journal. 162 (6): 266. arXiv:2109.10422. Bibcode:2021AJ....162..266L. doi:10.3847/1538-3881/ac27ab. S2CID 237592581.
^ Williams, D.R. (2004). "Sun Fact Sheet". NASA. Retrieved 2009-06-23.
^ HD 98649 at SIMBAD - Ids - Bibliography - Image.

Notes[]

^ Taking the absolute visual magnitude of HD 98649 $\scriptstyle M_{V_{\ast }}=4.91$ and the absolute visual magnitude of the Sun $\scriptstyle M_{V_{\odot }}=4.83$ , the visual luminosity can be calculated by $\scriptstyle {\frac {L_{V_{\ast }}}{L_{V_{\odot }}}}=10^{0.4\left(M_{V_{\odot }}-M_{V_{\ast }}\right)}$

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[van_Leeuwen2007-1] van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry

[Marmier2013-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.

[Gaia-DR2-3] Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

[Li2021-4] Li, Yiting; Brandt, Timothy D.; Brandt, G. Mirek; Dupuy, Trent J.; Michalik, Daniel; Jensen-Clem, Rebecca; Zeng, Yunlin; Faherty, Jacqueline; Mitra, Elena L. (2021). "Precise Masses and Orbits for Nine Radial-velocity Exoplanets". The Astronomical Journal. 162 (6): 266. arXiv:2109.10422. Bibcode:2021AJ....162..266L. doi:10.3847/1538-3881/ac27ab. S2CID 237592581.

[nssdc-6] Williams, D.R. (2004). "Sun Fact Sheet". NASA. Retrieved 2009-06-23.

[7] HD 98649 at SIMBAD - Ids - Bibliography - Image.

[luminosity_visual-5] Taking the absolute visual magnitude of HD 98649 $\scriptstyle M_{V_{\ast }}=4.91$ and the absolute visual magnitude of the Sun $\scriptstyle M_{V_{\odot }}=4.83$ , the visual luminosity can be calculated by $\scriptstyle {\frac {L_{V_{\ast }}}{L_{V_{\odot }}}}=10^{0.4\left(M_{V_{\odot }}-M_{V_{\ast }}\right)}$

[1]

[2]

[3]

[4]

[note 1]

[5]

[6]

Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Crater
Right ascension	11^h 20^m 51.769^s^[1]
Declination	–23° 13′ 02.43″^[1]
Apparent magnitude (V)	+8.00^[2]
Characteristics
Spectral type	G4V
B−V color index	+0.658 ± 0.003^[1]
Astrometry

Proper motion (μ)	RA: –199.28 ± 0.57^[1] mas/yr Dec.: –177.51 ± 0.48^[1] mas/yr
Parallax (π)	23.6832 ± 0.0489^[3] mas
Distance	137.7 ± 0.3 ly (42.22 ± 0.09 pc)
Absolute magnitude (M_V)	+4.91^[2]

Details

Mass	0.97 ± 0.02^[4] `M`_☉
Radius	~1^[2] `R`_☉
Luminosity (bolometric)	0.86^[2] `L`_☉
Luminosity (visual, L_V)	0.83^{[note 1]} `L`_☉
Surface gravity (log g)	4.38 ± 0.08^[2] cgs
Temperature	5759 ± 35^[2] K
Metallicity [Fe/H]	–0.02 ± 0.03^[2] dex
Rotation	27 ± 4.0 days^[2]
Rotational velocity (v sin i)	1.19^[2] km/s
Age	2.3 ± 2.0^[2] Gyr

Other designations
BD−22° 3121, HIP 55409, SAO 179793, LTT 4199
Database references
SIMBAD	data
Exoplanet Archive	data
Extrasolar Planets Encyclopaedia	data