* Astronomy

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RE: Comet 96P/Machholz 1

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Lowell Observatory Astronomer Confirms New Class of Comets
Comet 96P/Machholz 1 shows extremely anomalous compositional characteristics helping pinpoint its origin to one of three intriguing scenarios. David Schleicher, Lowell Observatory planetary astronomer, measured abundances of five molecular species in the comae of 150 comets and discovered that one comet, 96P/Machholz 1, has an extremely unusual chemistry. The exact cause of this chemical anomaly remains unknown, but each of three possible explanations will yield important but differing new constraints on the formation or evolution of comets. The study is published in the November issue of the Astronomical Journal.
The discovery of comet Machholz 1's extremely anomalous composition reveals the existence of a new class of comets. Astronomers identified two other classes in the 1990s. While Machholz 1 also has strongly depleted C2 and C3 carbon species, what makes it anomalous is that the molecule cyanogen, CN, is extremely depleted. In Machholz 1 CN is missing by about a factor of 72 from the average of other comets, i.e., only a little above one percent of normal.

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Title: The Unusual Spectrum of Comet 96P/Machholz
Authors: Laura E. Langland-Shula, Graeme H. Smith

We report spectra from 3000-5900 A for comet 96P/Machholz, obtained on 2007 Apr 27 UT with the 3-m Shane telescope at Lick Observatory. The spectra are extremely carbon poor, and show a prominent NH_2 series, but no CN emission. NH, NH_2, and C_2 gas production rates are (8.36 ± 2.18)x10^25, (29.88 ± 3.66)x10^25, and (4.52 ± 0.61)x10^23 molecules sec^-1, respectively, as determined from Haser model fits to the data. Upper limits to the gas production rates for CN and C_3 are 7.5x10^22 and 2.0x10^23, respectively. Though 96P is depleted in C_2 and C_3 relative to NH, it is even more depleted in CN than other so-called "carbon-chain depleted" comets.

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Credit: NASA

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After the notable comet (C/2006 P1) 2 months ago. The camera of the solar observation satellite SOHO, has spotted another comet that is now in range of the vision of LASCO C3.
Currently, the wide view of LASCO C3, has just captured comet (96P) as it is passing, (the comet approached the earth before in 2005 January (C/2004 Q2)).

The comet of 5.2 years in revolution period (96P), perihelion distance approximately 0.12 astronomical units (1 astronomical units because distance to the sun) with it is small extremely from the earth famous by the fact that rapid increase light it does, at the time of solar approach is. This time with the range of vision of SOHO it becomes bright to 2 classes, after that it is expected that in the middle of April in 8 classes it appears in the sky of the dawn.

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Live SOHO Satellite image:

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Comet Prospects for 2007
2007 is a poor year for returning comets and whilst it sees the possible return of 30 periodic comets only a few of these are likely to come within range of visual observation with moderate apertures. 8P/Tuttle may reach binocular brightness at the end of the year, though strictly it belongs with the comets of 2008. The highlight may be comet 2006 P1 (McNaught), although it has a faint absolute magnitude and may not survive perihelion.) 96P/Machholz should reach 2nd magnitude as it passes through the satellite coronagraph field at perihelion in early April, however it will be 9th magnitude by the time its elongation increases sufficiently for ground based observation in late April. UK observers may pick it up in the morning sky, but it will be a fading telescopic object. The orbit is very unusual, with the smallest perihelion distance of any proven short period comet (0.13 AU), which is decreasing further with time, a high eccentricity (0.96) and a high inclination (60°).

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Orbital Elements

The following orbital elements are taken from MPC 51822: 
Epoch 2007 Apr. 10.0 TT = JDT 2454200.5
T 2007 Apr. 4.6194 TT                                   MPC
q   0.124618             (2000.0)            P               Q
n   0.1881482      Peri.   14.6181      -0.2027322      -0.4629182
a   3.016264       Node    94.5507      +0.7888859      -0.5992693
e   0.958684       Incl.   59.9553      +0.5801368      +0.6531333
P   5.24
From 133 observations 1986-2002, mean residual 0".8.  Nongravitational
     parameters A1 = +0.01, A2 = -0.0002.

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2002 Hotshots
Astronomy magazine podcast: Don Machholz and Comet 96P
Orbital elements and diagram

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Comet 96P/Machholz can be seen in this SOHO satellite image as it passes around the Sun.

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Credit NASA