HD 98649

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

HD 98649

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 (MV)	+4.91[2]
Details
Mass	1 ± 0.03[2] M☉
Radius	~1[2] R☉
Luminosity (bolometric)	0.86[2] L☉
Luminosity (visual, LV)	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

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]

The HD 98649 planetary system[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	>6.8 ± 0.5 MJ	5.6 ± 0.4	4951^+607 −465	0.85 ± 0.05	—	—

Sun comparison

Chart compares the Sun to HD 98649.

− − − − − −

Identifier −	J2000 Coordinates −		Distance (ly) −	Stellar Class −	Temperature (K) −	Metallicity (dex) −	Age (Gyr) −	Notes −
	Right ascension −	Declination −
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

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.Vizier catalog entry
2. 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.
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.
4. "hd_98649_b".
5. Williams, D.R. (2004). "Sun Fact Sheet". NASA. Retrieved 2009-06-23.
6. HD 98649 at SIMBAD - Ids - Bibliography - Image.

Notes

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