Three new possible Taurid complex members

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 Updated on November 28, 2005

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* Overview

Katsuhito Ohtsuka pointed out that a new asteroid 2005 TF50 is a member of Taurid complex.

Adam Hurcewicz and Masayuki Suzuki pointed out that another two new asteroids 2005 UW6 and 2005 UY6 can be also members of Taurid complex.

Comet 2P/Encke is the main component of Taurid complex. The orbital elements of the three new asteroids are similar to those of Comet 2P/Encke.


2P/Encke2005 TF502005 UW62005 UY6
q0.338 A.U.0.294 A.U.0.523 A.U.0.287 A.U.
e0.8470.8690.7430.873
L161161155164
B-14-0-0
Peri.186160180181
Node3351335344
Incl.1211112
P3.3 years3.4 years2.9 years3.4 years
H14.2 mag20.2 mag21.8 mag18.2 mag

Comet 2P/Encke looks asteroidal around the aphelion with an absolute magnitude of H = 14.2 mag. You can see the light curve of Comet 2P/Encke at:

http://www.aerith.net/comet/catalog/0002P/2003.html

If the three new asteroids were really associated with Comet 2P/Encke, they might showed cometary activity around the perihelion.

Assuming the cometary light curve similar to Comet 2P/Encke and the brightness difference based on the absolute magnitude H, here shows the ephemeris of these three new asteroids with impracticable brightness prediction. Observations are encouraged.

In 2005, we have two bright new periodic comets, originally reported as faint asteroids, P/2005 JQ5 and 169P/2002 EX12. The nuclear absolute magnitude of them are 17.5 mag and 16.0 mag respectively. The brightness of 2005 UY6 is similar to them. The other two may be too faint to show the cometary activity.

* 2005 TF50

2005 TF50 was discovered on 2005 October 10 at 21.1 mag by M. Block, Steward Observatory, Kitt Peak, and announced in M.P.E.C. 2005-T83:

http://cfa-www.harvard.edu/mpec/K05/K05T83.html

The absolute magnitude of 20.2 mag. So 2005 TF50 is fainter than Comet 2P/Encke by 6 mag. Assuming the light curve similar to Comet 2P/Encke, 2005 TF50 may be very bright in the evening sky in 2005 November and December.

The condition in this autumn is excellent to detect the cometary activity of 2005 TF50. Although the brightness prediction in M.P.E.C. is extremely faint, observations are encouraged.

Here is the light curve of 2005 TF50:

The red curve shows the brightness if it shows cometary activity similar to Comet 2P/Encke. The green curve shows the brightness as an asteroid.

Here is the ephemeris in the Northern Hemisphere based on the orbital elements calculated from 27 observations between Oct. 10 and 23: 

2005 TF50
  Date     R.A.      Decl.     r       d     Ph.A Elong   m1    m2   Best Time(A, h)  
Oct. 10   1  9.85   16 15.4   1.699   0.706    5   170   20.8  21.1  23:50 (  0, 71)  
     15   0 52.57   15 39.2   1.634   0.643    5   170   20.2  20.8  23:13 (  0, 71)  
     20   0 32.26   14 45.2   1.568   0.589   10   163   19.5  20.7  22:33 (  0, 70)  
     25   0  9.11   13 30.6   1.500   0.543   17   153   18.9  20.7  21:50 (  0, 68)  
     30  23 43.67   11 54.6   1.430   0.508   24   142   18.2  20.7  21:05 (  0, 67)  
Nov.  4  23 16.80    9 59.3   1.358   0.482   33   131   17.5  20.7  20:19 (  0, 65)  
      9  22 49.50    7 50.0   1.283   0.465   42   119   16.8  20.7  19:32 (  0, 63)  
     14  22 22.64    5 33.4   1.206   0.455   51   107   16.1  20.8  18:46 (  0, 60)  
     19  21 56.74    3 15.5   1.126   0.451   60    95   15.4  20.9  18:20 (  9, 58)  
     24  21 31.89    0 59.9   1.043   0.451   70    84   14.7  21.0  18:18 ( 26, 53)  
     29  21  7.80   -1 12.5   0.957   0.455   80    72   14.5  21.2  18:18 ( 40, 46)  
Dec.  4  20 43.76   -3 23.8   0.867   0.460   90    61   14.2  21.4  18:18 ( 50, 38)  
      9  20 18.83   -5 38.7   0.774   0.467  102    50   13.9  21.7  18:18 ( 58, 29)  
     14  19 51.94   -8  3.2   0.677   0.479  115    38   13.5  22.3  18:19 ( 65, 18)  
     19  19 22.43  -10 43.1   0.577   0.501  131    25   13.1  23.4  18:21 ( 71,  7)  
     24  18 50.91  -13 40.4   0.476   0.541  150    13   12.7  25.8  18:24 ( 77, -5)  
     29  18 20.96  -16 51.1   0.382   0.613  162     6   12.3  28.8   5:36 (282,-13)  
Jan.  3  18  0.78  -20  4.7   0.311   0.735  136    12   12.1  23.4   5:38 (290, -6)  
      8  18  0.06  -22 59.1   0.297   0.903   96    17   12.4  20.8   5:38 (295, -4)  
     13  18 17.05  -25  1.5   0.349   1.079   64    18   13.3  20.4   5:38 (298, -5)  
     18  18 40.65  -26  6.3   0.438   1.234   46    18   14.2  20.6   5:38 (298, -6)  
     23  19  4.43  -26 30.1   0.537   1.366   36    18   15.1  21.0   5:36 (297, -7)  
     28  19 26.48  -26 28.2   0.638   1.482   30    19   16.1  21.4   5:34 (297, -8)  
Feb.  2  19 46.49  -26 10.4   0.736   1.584   26    19   17.2  21.7   5:31 (296, -8)  
      7  20  4.59  -25 42.7   0.830   1.676   24    20   18.2  22.1   5:28 (296, -9)  
     12  20 20.98  -25  9.0   0.922   1.759   23    22   19.0  22.4   5:24 (295, -8)  
     17  20 35.92  -24 31.7   1.009   1.833   23    23   19.7  22.6   5:19 (294, -8)  
     22  20 49.58  -23 52.4   1.093   1.900   22    25   20.3  22.9   5:14 (294, -7)  
     27  21  2.14  -23 12.3   1.175   1.960   22    27   20.9  23.1   5:08 (294, -7)  
Mar.  4  21 13.72  -22 32.3   1.253   2.013   23    29   21.4  23.3   5:02 (293, -6)

Even if it were a bright comet, it had been too difficult to detect the cometary activity in its last several perihelion passages, except for 1995 October, when it must have been bright in the morning sky.

Tomohiko Sekiguchi pointed out that the condition in next return in 2009 is very bad.

A remarkable rendezvous event happens during this campaign. 2005 TF50 will pass extremely close by Comet 168P/Hergenrother on November 16. 

2005 Nov. 16  12h UT  0.032 deg (  1.9 arcmin)
  2005 TF50			22h09m.6  +04o24'  20.8 mag
  168P/2005 N2 ( Hergenrother )	22h09m.7  +04o24'  16.7 mag

* 2005 UW6

2005 UW6 was discovered on 2005 October 29 at 20.9 mag by R. S. McMillan, Steward Observatory, Kitt Peak, and announced in M.P.E.C. 2005-U102:

http://cfa-www.harvard.edu/mpec/K05/K05UA2.html

Comet 2P/Encke begins to show the cometary activity 100 days prior to the perihelion passage. But 2005 UW6 was discovered 66 days prior to the perihelion passage as an asteroid. It is much fainter than Comet 2P/Encke. The perihelion distance is much larger than Comet 2P/Encke. Therefore, it is less likely to show the cometary activity.

It passes only 0.05 A.U. from the earth on November 19 and it is observable in good condition in mid November.

Here is the ephemeris in the Northern Hemisphere based on the orbital elements calculated from 48 observations between Oct. 29 and Nov. 19: 

2005 UW6
 Date      R.A.      Decl.     r       d     Ph.A Elong   m2   Best Time(A, h)
Nov.  1   4 34.52   26 12.8   1.222   0.262   25   147   20.5   1:53 (  0, 81)
      4   4 43.36   27 13.1   1.184   0.219   26   148   20.1   1:50 (  0, 82)
      7   4 55.91   28 35.8   1.145   0.177   27   148   19.6   1:50 (  0, 83)
     10   5 15.80   30 36.3   1.107   0.136   29   146   19.0   1:57 (  0, 85)
     13   5 52.79   33 41.0   1.067   0.098   35   140   18.4   2:20 (  0, 88)
     16   7 18.73   37 40.1   1.028   0.064   51   126   17.8   3:29 (180, 88)
     19  10 35.50   31 28.3   0.988   0.046   88    88   18.2   5:10 (273, 73)
     22  13 17.31    8 21.7   0.948   0.060  130    47   21.3   5:12 (281, 31)
     25  14 21.80   -4 10.0   0.908   0.092  147    29   24.4   5:15 (283, 12)
     28  14 51.63   -9 50.5   0.868   0.131  153    23   26.2   5:17 (286,  5)
Dec.  1  15  8.61  -12 54.5   0.828   0.172  154    20   27.0   5:19 (288,  3)

The conditions had been very bad in every perihelion passage during last 15 years.

* 2005 UY6

2005 UY6 was discovered on 2005 October 29 at 19.9 mag by R. Bambery, M. Hicks, K. Lawrence, E. Helin, R. Thicksten in the course of NEAT, and announced in M.P.E.C. 2005-U103:

http://cfa-www.harvard.edu/mpec/K05/K05UA3.html

The absolute magnitude of 18.2 mag. So 2005 UY6 is fainter than Comet 2P/Encke by 4 mag. Assuming the light curve similar to Comet 2P/Encke, 2005 UY6 may be very bright in the evening sky in 2006 January.

Here is the light curve of 2005 UY6:

The red curve shows the brightness if it shows cometary activity similar to Comet 2P/Encke. The green curve shows the brightness as an asteroid.

Here is the ephemeris in the Northern Hemisphere based on the orbital elements calculated from 24 observations between Oct. 29 and Nov. 20: 

2005 UY6
 Date      R.A.      Decl.     r       d     Ph.A Elong   m1    m2   Best Time(A, h)
Nov.  1  23 34.93   12 21.1   1.840   0.974   20   138   20.4  20.5  20:50 (  0, 67)
     11  23 12.36    9 50.2   1.717   0.962   28   123   19.6  20.6  19:49 (  0, 65)
     21  22 54.65    7 31.5   1.588   0.966   36   108   18.7  20.6  18:52 (  0, 62)
Dec.  1  22 42.23    5 37.0   1.450   0.976   42    95   17.8  20.6  18:18 (  9, 60)
     11  22 34.60    4 10.0   1.304   0.981   48    83   16.6  20.6  18:19 ( 30, 56)
     21  22 30.63    3  6.7   1.147   0.972   54    71   15.2  20.4  18:22 ( 46, 49)
     31  22 28.76    2 17.0   0.978   0.941   61    61   14.1  20.2  18:28 ( 58, 41)
Jan. 10  22 26.47    1 19.9   0.795   0.881   71    50   13.3  19.9  18:36 ( 67, 31)
     20  22 18.08   -0 39.6   0.598   0.789   89    37   12.2  19.7  18:44 ( 75, 19)
     30  21 48.31   -6 26.3   0.397   0.687  128    18   10.7  21.0  18:52 ( 82, -1)
Feb.  9  20 47.93  -18 17.3   0.287   0.747  140    10    9.9  21.8   5:26 (284,-12)
     19  20 42.54  -23  1.4   0.416   1.035   71    23   11.7  18.9   5:17 (293, -7)
Mar.  1  21  7.32  -22 37.0   0.618   1.278   49    28   13.6  19.5   5:06 (293, -6)
     11  21 32.13  -21 12.2   0.814   1.459   40    32   15.7  20.2   4:53 (292, -5)
     21  21 53.60  -19 38.4   0.995   1.594   36    36   17.3  20.7   4:38 (291, -4)
     31  22 11.84  -18  9.3   1.163   1.693   35    42   18.5  21.1   4:23 (291, -2)

Even if it were a bright comet, it had been too difficult to detect the cometary activity in its last several perihelion passages, except for 1995 November, when the condition was excellent.

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