Pollux b

Pollux b / ThestiasDiscovery[1]

Discovered by| Hatzes et al.
Discovery site| United States
Discovery date| 16 June 2006

Detection method

| Radial velocity
Designations

Alternative names

| β Geminorum b, HD 62509 b, Thestias[2]
Orbital characteristics[1]

Semi-major axis

| 1.64 ± 0.27 AU (245 ± 40 million km)
Eccentricity| 0.02 ± 0.03
Orbital period| 589.64 ± 0.81 d
1.61432 ± 0.00222 y
astron|astron|helion}}| 2,447,739.02 ± 4.5
Semi-amplitude| 41.0 ± 1.6
Star| Pollux
Physical characteristics[1]
Mass| ≥2.30±0.45 MJ

Pollux b, formally named Thestias /ˈθɛstiəs/, is an exoplanet candidate orbiting the star Pollux approximately 34 light-years away in the constellation of Gemini (the Twins). It is also designated β Geminorum b (Latinized to Beta Geminorum b, abbreviated β Gem b) or HD 62509 b. If this planet exists, it has a minimum mass of about twice the mass of Jupiter, and it moves around Pollux in 1.61 years at a distance of 1.64 astronomical unit|AU in a nearly circular orbit.[1] However, its existence has been disputed.[3]

## Contents

* 1 History of observations
* 2 Naming
* 3 See also
* 4 References
* 5 External links

## History of observations

The discovery of Pollux b was announced in 2006 by astronomer Artie P. Hatzes and co-authors using the radial velocity method.[1] A planet orbiting Pollux had previously been hypothesized by Hatzes in 1993, though at that time it was thought more likely that the radial velocity variations were caused by intrinsic stellar variability.[4]

An independent study published shortly after the discovery paper supported the existence of Pollux b, but expressed some uncertainty, leaving a non-planetary explanation for the radial velocity variations a possibility.[5] Another independent study in 2008 also supported the planet.[6]

The planet's existence has been questioned by two subsequent studies, one in 2013 and its 2021 follow-up.[7][3] A weak magnetic field in Pollux was detected in 2009,[8] and it was suggested that magnetic variability in the star, as opposed to a planet, might be the cause of the observed radial velocity variations. The stellar rotation period was found to be close to the proposed period of Pollux b, casting some doubt on the planet's existence.[7] The 2021 study monitored Pollux for 4.25 years and found the rotational period to be 660±15 d, close to Pollux b's orbital period of 590 days. Even though both values aren't equal, there might still be systematic errors in the rotational period.[3]

## Naming

In July 2014 the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.[9] The process involved public nomination and voting for the new names.[10] In December 2015, the IAU announced the winning name was Thestias for this planet.[2] The winning name was based on that originally submitted by theSkyNet of Australia; namely Leda, Pollux's mother in Greek and Roman mythology. At the request of the IAU, 'Thestias' (the patronym of Leda, a daughter of Thestius) was substituted. This was because 'Leda' was already attributed to an asteroid and to one of Jupiter's satellites.[11][12]

## See also

* Gemini in Chinese astronomy
* Cancer Minor (constellation) – Obsolete constellation inside modern Gemini
* Sudarsky's gas giant classification

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 A. P. Hatzes (2006). "Confirmation of the planet hypothesis for the long-period radial velocity variations of β Geminorum". Astronomy and Astrophysics 457 (1): 335–341. doi:10.1051/0004-6361:20065445. Bibcode: 2006A&A...457..335H.
2. ↑ 2.0 2.1 Final Results of NameExoWorlds Public Vote Released , International Astronomical Union, 15 December 2015.
3. ↑ 3.0 3.1 3.2 Aurière, M. et al. (February 2021). "Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet". Astronomy & Astrophysics 646: A130. doi:10.1051/0004-6361/202039573. Bibcode: 2021A&A...646A.130A.
4. ↑ A. P. Hatzes (1993). "Long-period radial velocity variations in three K giants". The Astrophysical Journal 413: 339–348. doi:10.1086/173002. Bibcode: 1993ApJ...413..339H.
5. ↑ S. Reffert (2006). "Precise Radial Velocities of Giant Stars. II. Pollux and Its Planetary Companion". The Astrophysical Journal 652 (1): 661–665. doi:10.1086/507516. Bibcode: 2006ApJ...652..661R.
6. ↑ Han, In-Woo et al. (June 2008). "Confirmation of the Exoplanet around β GEM from the RV Observations Using Boes". Journal of the Korean Astronomical Society 41 (3): 59–64. doi:10.5303/JKAS.2008.41.3.059. Bibcode: 2008JKAS...41...59H.
7. ↑ 7.0 7.1 Aurière, Michel; Konstantinova-Antova, Renada (August 2014). "Pollux: a stable weak dipolar magnetic field but no planet?". Magnetic Fields throughout Stellar Evolution. 302. pp. 359–362. doi:10.1017/S1743921314002476. Bibcode: 2014IAUS..302..359A.
8. ↑ Aurière, M. et al. (September 2009), "Discovery of a weak magnetic field in the photosphere of the single giant Pollux", Astronomy and Astrophysics 504 (1): 231–237, doi:10.1051/0004-6361/200912050, Bibcode: 2009A&A...504..231A
9. ↑ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars . IAU.org. 9 July 2014
10. ↑ "NameExoWorlds The Process". http://nameexoworlds.iau.org/process.
11. ↑ "NameExoWorlds The Approved Names". http://nameexoworlds.iau.org/names.
12. ↑ YOU helped name an exoplanet! , TheSkyNet, 2015-12-17

## External links

* "Pollux". SolStation. http://www.solstation.com/stars2/pollux.htm.

Coordinates:  07h 45m 19.4s, +28° 01′ 35″

* v
* t
* e

Gemini constellation

Stars
(list)|

| Bayer|

* α (Castor)
* β (Pollux)
* γ (Alhena)
* δ (Wasat)
* ε (Mebsuta)
* ζ (Mekbuda)
* η (Propus)
* θ
* ι
* κ
* λ
* μ (Tejat)
* ν
* ξ (Alzirr)
* ο (Jishui)
* π
* ρ
* σ
* τ
* υ
* φ
* χ
* ω

|

Flamsteed|

* 1
* 2
* 3
* 4
* 5
* 6
* 8
* 9
* 10
* 11
* 12
* 14
* 15
* 16
* 19
* 20
* 22
* 23
* 25
* 26
* 28
* 30
* 32
* 33
* 35
* 36 (d)
* 37
* 38 (e)
* 39
* 40
* 41
* 44
* 45
* 47
* 48
* 49
* 51
* 52
* 53
* 56
* 57 (A)
* 58
* 59
* 61
* 63
* 64 (b1)
* 65 (b)
* 67
* 68
* 70
* 74 (f)
* 76 (c)
* 79
* 81 (g)
* 82
* 84
* 85
* 141 Tau

Variable|

* R
* U
* W
* RR
* RW
* RX
* RY
* SS
* TU
* TV
* WY
* ZZ
* AD
* AF
* AL
* AW
* BG
* BM
* BN
* CR
* DM
* DN
* DX
* IR
* IS
* NP
* NQ
* NZ
* OT
* OU
* OY
* PQ
* PS
* PZ
* V345

HR|

* 2111
* 2169
* 2277
* 2304
* 2340
* 2366
* 2391
* 2417
* 2436
* 2439
* 2449
* 2457
* 2499
* 2533
* 2586
* 2597
* 2632
* 2635
* 2643
* 2649
* 2651
* 2660
* 2665
* 2669
* 2673
* 2692
* 2757
* 2780
* 2858
* 2877
* 2896
* 2926
* 2931
* 2936
* 2951
* 2953
* 2962
* 2965
* 2978
* 3030
* 3040
* 3053

HD|

* 44780
* 45314
* 50554
* 54986
* 56176
* 58898

Gliese|

* Gliese 232
* Gliese 251
* GJ 1093

Other|

* BD+20°1790
* CXOU J061705.3+222127
* Geminga
* HAT-P-20
* HAT-P-24
* HAT-P-33
* HAT-P-39
* LB-1
* 2MASS 0727+1710
* 2MASSW J0746425+200032
* PSR B0611+22
* PSR B0656+14
* PSR J0751+1807
* WD J0651+2844
* WISEP J060738.65+242953.4

Star clusters|

| Association|

* Gemini OB1

|

Open|

* IC 2157
* Messier 35
* NGC 2129
* NGC 2158
* NGC 2224
* NGC 2234
* NGC 2248
* NGC 2265
* NGC 2266
* NGC 2304
* NGC 2331
* NGC 2355
* NGC 2356
* NGC 2395
* NGC 2420

Globular|

* Koposov II

Nebulae|

| HII|

* Sh2-247

|

Planetary|

* Eskimo Nebula
* Medusa Nebula
* NGC 2371-2

Reflection|

* IC 444

SNR|

* IC 443

Galaxies|

| NGC|

* 2274
* 2275
* 2288
* 2289
* 2290
* 2291
* 2294
* 2333
* 2339
* 2341
* 2342
* 2357
* 2365
* 2370
* 2373
* 2375
* 2376
* 2379
* 2385
* 2388
* 2389
* 2393
* 2398
* 2405
* 2406
* 2407
* 2410
* 2411
* 2418
* 2435
* 2449
* 2450
* 2454
* 2480
* 2481
* 2486
* 2487
* 2490
* 2492
* 2498

|

Other|

* 1ES 0647+250
* IC 2196

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