The Professor Comet s Report. Early Spring April 2012

Transcription

1 1 Mr. Justin J McCollum (BS, MS Physics) Lab Physics Coordinator Dept. of Physics Lamar University Welcome to the comet report which is a monthly article on the observations of comets by the amateur astronomy community and comet hunters from around the world! This article is dedicated to the latest reports of available comets for observations, current state of those comets, future predictions, & projections for observations in comet astronomy! C/2009 P1 Garradd with Barred Spiral Galaxy NGC March 2011!

2 2 The Current Status of the Predominant Comets for Apr 2012! Comets Designation (IAU MPC) Orbital Status Magnitude Visual Trend Observation (Range in Lat.) Constellations (Night Sky Location) Garradd 2009 P1 C 7.0* Fading 90 N 30 S SW region of Ursa Major moving SSW towards the SE region of Lynx. Giacobini - Zinner 21P P 9 10 Fading Poor Elongation Lost in the daytime Glare! Visibility Period All Night N/A LINEAR 2011 F1 C 11.7* Brightening 90 N 20 S Undergoing retrograde motion between Boötes and Draco thru the late Spring. Gehrels 2 78P P 12.2* Fading 60 N - 20 S Moving eastwards across Taurus and progressing along the N edge of the Hyades Star Cluster! McNaught 2011 Q2 C 12.5 Fading 70 N Eqn. Currently in the S central region of Andromeda moving NE between the boundary between Andromeda & Pisces. NEAT 246P/2010 V2 P 12.3* - 13 Possible Steadiness 65 N - 60 S McNaught 2009 F4 C 12.8* - 14 Steady Poor Elongation Undergoing retrograde motion in the E half of the N central region of Virgo until late June. Lost in the daytime Glare! All Night Early Evening Early Morning All Night N/A *Visual Magnitude determined from last known field observation report! Comets with visually reported at visual magnitude values fainter than 13.5 are not reported on this list!

3 3 Ephemeris Data Terminology Ephemeris Term Date TT Definition (plus additional comments) Month and Year using the standard Gregorian calendar. Terrestrial Time (Day of the Month) as a substitute for the astronomical Julian date. RA (2000) Right Ascension based on the Epoch J2000 (longitudinal coordinate for the celestial sky) measured in hours, minutes, and seconds. Dec (2000) Declination based on the Epoch J2000 (latitudinal coordinate for the night sky) measured in degrees, arcminutes, and arcseconds. Delta The distance from Earth measured in AUs (1 AU = 1 Astronomical Unit = mi = km as the mean distance between the Earth and Sun). R The solar distance measured in AUs (the distance between the comet or comet like body and the Sun)! Elongation Solar elongation which is the angle of separation between the observed object and the Sun as measured across the night sky as measured in degrees. Phase Phase angle between the Sun, the celestial object, and the observer on the surface of the Earth. Also known as the Sun Object Observer angle. M1 M2 /min M1: The visual magnitude of the celestial object as observed on the surface of the Earth at sea level. (Note M1 values predicted by the Minor Planet Center can differ from actual visual reports obtain in the field!) The nuclear magnitude of the Comet which is also the visual magnitude of the false nucleus. (Rarely shown on a Comet s ephemeris data spreadsheet unless all values show a visual brightness value above 19 th magnitude!) The progression or motion across the sky as measured in arcseconds per minute. P.A. Moon Phase Foreshortening (% Fore.) Position angle while undergoing motion in the celestial sky. (P.A. is the same method applied to binary stars with starts at N goes counterclockwise in an easterly direction!) A Numerical value for designating the phases of the Moon on a scale of ( ): A New Moon = 0.00, Waxing or Waning Crescent = ( ), Half Moon (1 st or Last Quarter = 0.50), Waxing or Waning Gibbous = ( ), & Full Moon = 1.00 The appearance of the comet s tail due to the geometric orientation between the Earth and a Comet. (100% means the comet s tail is parallel with the face of the Earth where as 0% means the tail is exactly perpendicular with respect to the face of the Earth!)

4 Degree of Condensation (DC) 4 All observations of comets are broken down into three factors: estimating magnitudes for light curves to predict future brightness, coma observations, and observations that concern with a comet s tail(s). For the coma or a comet s head there two characteristic features that are important for study: Degree of condensation (DC) and coma size measured in arcminutes. The classification system for determining the DC is based on a positive integer system from 0 to 9 as shown below. DC value Definition to numerical DC designation 0 Diffuse coma of uniform brightness 1 Diffuse coma with slight brightening towards center 2 Diffuse coma with definite brightening towards center 3 Centre of coma much brighter than edges, though still diffuse 4 Diffuse condensation at centre of coma 5 Condensation appears as a diffuse spot at centre of coma described as moderately condensed 6 Condensation appears as a bright diffuse spot at centre of coma 7 Condensation appears like a star that cannot be focused described as strongly condensed 8 Coma virtually invisible 9 Stellar or disk like in appearance

5 5 The Professor Comet s Report A Synopsis of the Predominant Comets for the New Year 2012! Comet Garradd with its progression past perihelion and perigee has now set a path to travel beyond the asteroid belt into the outer Solar system for the Spring season of The comet is now moving in a southerly direction through the western region of the constellation of Ursa Major (home to the famous Big Dipper asterism) and expected to cross the boundary between the constellations of Ursa Major and Lynx the evening of 15 April 2012 at 23:00 CST. Prior to its crossing it will move thru the last leap of the Gazelle (the hop of the Gazelle across Ursa Major by the pattern three pairs of stars representing the feet of Ursa Major) the Talitha stars the early morning of 14 April. Expect the comet to continue with its southerly path advancing deeper and across the eastern areas of Lynx well into mid May. Garradd will alter course once it enters the constellation region of Cancer and head southeast, but remaining within the Crab through the early middle of the Summer season, but confined to the NE and east central regions of the Crab! The comet will pass closely to several stars along the SW area of Ursa Major, SE area of Lynx, and a few spiral galaxies with a visual magnitude fainter than Look towards the spreadsheets on pages 12 & 13 for further information on the brightest stars and primary DSOs (Deep Sky Objects) that will be within the vicinity or in the same region of the sky where comet Garradd will be located for most of the Spring season! The current conditions of C/2009 P1 have it a maximum brightness of visual magnitude 7.0 last reported on March 30 with a current angular size reported between or 10.4% % the size of an average full Moon. The comet has a current DC value of 7 which indicates a tightly, compacted coma that allows the comet to appear to stellar like, but lacking in the tight resolution required for it to have a well defined boundary. It is still visible in binoculars however the fan shaped tail has been visually observed since last month. The confirmed sighting on March 28 give a field observation report with the dust tail at an angular length of 0.7 (42 or ~1 1/3 full moon widths) at a PA of 40 orienting the tail to the NE of the coma. No visual reports have been given on the ion tail recently although the last image taken on 14 March show a 100 separation between the two tails. Comet Garradd s ion tail would then be placed at a PA of 140 ; projecting SE from the coma and is faint enough to require moderate telescopes under dark sky conditions to observe it or at least the dust tail which will be a few magnitudes brighter than the ion tail. Expect Comet garradd to fade in brightness until it is about 12 th magnitude around the last week of May, but position at a very low angle of altitude for northern hemisphere observers between late April thru most of June. Garradd s solar elongation will decrease to 90 by 23 April and will be reduced to 60 by 30 May as the winter constellations start to fade into the daytime sky for the rest of Spring well into Fall Autumn!

6 6 The Professor Comet s Report A Synopsis of the Predominant Comets for the New Year 2012! There are no other comets that are prominent right now nor are any of the known cometary bodies currently being monitored are expected to get brighter than 8 th or 8 th magnitude expect comet 96P/Machholz 1 which is expected to be visible this summer during the months of July and August in the evening hours before midnight! Comet Machholz 1 is currently progressing eastward thru the northern edge of the southern constellation of Grus the Crane and will move into the neighboring constellation of Sculptor by late April and move quickly thru the Winter Hexagon asterisms of the winter constellations from mid June and most of early July lost in the daytime glare. However, once it is visible sometime in mid July it will be located between Lynx and Cancer low in the evening skies just after sunset with the planet Mars setting during the months of mid Summer. As we move into the month of August the comet will have shifted its position further east towards the following in succession; Coma Berenices (25 July 6 Aug), Virgo (6 7 Aug), Boötes (7 13 Aug), Virgo in its NE region (13 22 Aug), and Libra thru the end of August. Machholz 1 will reach a predicted maximum brightness of visual magnitude 7.0 by the month of July. However, the comet has a solar elongation below 60, so it will be difficult to see positioned at a sky altitude below 30 during the hours of dusk making a very difficult object to observe thru so much air and the effects of atmospheric refraction and mirage effects close to the distant horizon! Current predictions are placing this comet as a maximum brightness of visual magnitude -0.l (~6% brighter than Arcturus) and located in the constellation of Gemini the period of 1-2 July, but with a solar elongation of 1 3 degrees! Once future prospect is in 2013 with the discovery of C/2011 L4 (PanSTARRS) discovered using 1.8m Pan STARRS 1 RC telescope on the Hawaiian islands, USA the night of 6 June 2011 between 09:36 10:32 UTC or 04:36 05:32 AM local Hawaiian time. Comet PanSTARRS L1 is predicted to become the Great Comet of 2013 reaching a maximum brightness of 0.5 visual magnitude the evenings of March 2013, but with the unfortunate solar elongation of only 15 while residing along the constellation boundary between Cetus and Pisces close to where the planet Uranus is currently resides. Right at the present the comet is undergoing a wide retrograde motion which began in late Sept, 2011 and ends also in late Sept, 2011 moving from Libra to Ophiuchus thru Scorpius and back to Libra. There are no opportunities to observe the comet based on the current ephemeris and orbital data calculated for it so far, the comet will be at solar elongation values of less than 18 and 61 when it is brighter than 12 th and fading to 8 th magnitude upon reaching and receding from perihelion respectfully. This period lasts from 8 Nov 2011 thru 8 May 2012 when it is moving SE from Lupus (The Wolf) across the constellations of the Summer sky towards Microscopium and then head NE thru the Autumnal sky past Andromeda and into Cepheus by early May, 2012! C/2011 L4 is predicted to reach a perihelion of 0.30 AU or 27,870,000 mi (44,842,830 km) the period of March 2011 around the time of maximum brightness and perigee of 1.10 AU or 102,190,000 mi (164,423,371 km) the period of 3 8 March 2011 prior to perihelion. Models in predicting the future path of non periodic comets can change and the future data gathering on the projected path and orbital elements can change overtime and this includes comet PanSTARRS L1; stay tuned for future change in details if any!

7 7 C/2009 P1 Garradd Figure 1: Garradd P1 projected path across the Spring Constellations: Mid March Late May, 2012! N E W S Courtesy of SkyTools 3 Profession Ed, 2012.

8 8 C/2009 P1 Garradd Figure 2: Close up of Garradd s projected path from 23 Mar 23 Apr 2012! N NGC 2805 E Hickson 56 Hickson S 50 NGC 3631 W Hickson 45 υ UMa CS UMa φ UMa 16 UMa 18 UMa Muscida JnEr 1 26 UMa Sarir NGC UMa 27 Lyn NGC 2552 NGC 2541 NGC Lyn NGC 3198 Talitha Australis Talitha Borealis 34 Lyn Hickson 41 Tania Borealis Tania Australis 36 Lyn 10 Lyn 35 Lyn Alsciaukat Courtesy of SkyTools 3 Profession Ed, 2012.

9 9 C/2009 P1 Garradd Figure 3: Garradd s projected path from Ursa Major to Lynx from 1 Apr 1 May 2012! N E W S Courtesy of Winnie s Comet Pages, 2012.

10 10 C/2009 P1 Garradd Figure 4: Garradd s projected path thru Ursa Major from (1 15) Apr 2012! N E W S Courtesy of Winnie s Comet Pages, 2012.

11 11 C/2009 P1 Garradd Figure 4: Garradd s projected path thru Lynx from (16 Apr 1 May) 2012! N E W S Courtesy of Winnie s Comet Pages, 2012.

12 12 The Professor Comet s Report Bright Stars in Hercules along the Spring path of Comet Garradd Star Common Designations Vis. Mag Classification Stellar Attributes R.A. (2000) Dec (2000) Distance (lys) 23 UMa HR 3757, HD 81937, SAO UMa HR 3648, HD 79028, SAO F0 IV Suspected Variable 9h 31m 31.8s F9 V None 9h 14m 20.5s Upsilon (υ) UMa HR 3888, HD 84999, SAO 27401, TYC CS UMa HR 3870, HD 84335, SAO 27377, TYC F2 IV Variable Type: Delta (δ) Scuti 5.14 M3 IIIab Variable Type: Slow Irregular GCVS type LB 9h 50m 59.1s h 46m 31.7s Phi (φ) UMa 30 UMa, HR 3894, HD 85235, SAO A3 IV None 9h 52m 6.4s UMa DD UMa, HR 3662, HD 79439, SAO 27191, TYC A5 V Variable Type: Delta (δ) Scuti 9h 16m 11.4s UMa HR 3799, HD 82621, SAO 27298, TYC A2 V None 9h 34m 49.3s Sarir Theta (θ) UMa, HR 3775, HD 82328, SAO F7 IV Suspected Variable (/ Mag) 9h 32m 50.5s UMa HR 3619, HD 78209, SAO 27136, TYC A1 V None 9h 8m 52.1s Talitha Borealis Iota (ι) UMa, 9 UMa, HR 3569, HD A7 IV Quadruple Star System Suspected Variable 8h 59m 12.0s Talitha Australis Kappa (κ) UMa, 12 UMa, HR 3594, HD A0 IV-V Suspected Variable (/ Mag) 9h 3m 37.5s Lyncis HR 3508, HD 75506, SAO 42576, 5.15 G8 III None 8h 51m 56.8s

13 13 The Professor Comet s Report Common DSOs near the Spring path of Comet Garradd C/2009 P1 DSO Common Designations Vis. Mag Classification DSO Attributes R.A. (2000) Dec (2000) Distance (lys) NGC 2805 MCG , UGC 4936, PGC Spiral Galaxy Hubble Type: SABc (Nearly Face On) 9h 20m 20.1s million Hickson 45 HCG (brightest member) Hickson 50 HCG (brightest member) Compact Galaxy Group Compact Galaxy Group 4 Members 10h 19m 11.2s >300 million 5 Members 11h 17m 06.1s >300 million NGC 3631 Arp 27, MCG , UGC 6360, PGC Spiral Galaxy Hubble Type: Sc (Nearly Edge On) 11h 21m 02.4s million Jones Emb erson 1 JnEr 1, PK , ARO (central star 16.8 Mag) Planetary Nebula Ring Structure (Face On) 7h 57m 51.6s Hickson 56 HCG (brightest member) Compact Galaxy Group 5 Members 11h 32m 31.9s million NGC 2500 MCG , UGC 4165, PGC Barred Spiral Galaxy Hubble Type: Scd (Face On) 8h 1m 52.9s million NGC 2841 MCG , UGC 4966, PGC NGC 2552 MCG , UGC 4325, PGC NGC 2541 MCG , UGC 4284, PGC NGC 3198 MCG , UGC 5572, PGC Spiral Galaxy Hubble Type: Sb (Intermediate) 12.7 Irregular Galaxy Hubble Type: SABm 12.2 Spiral Galaxy Hubble Type: SABc (Intermediate) 10.9 Spiral Galaxy Hubble Type: Sc (Intermediate) 9h 22m 02.5s million 8h 19m 19.6s n/a 8h 14m 40.1s million 10h 19m 55.0s million Hickson 41 HCG (brightest member) Compact Galaxy Group 4 Members 9h 57m 39.5s >300 million

14 14 IAU MPC Ephemeris data for C/2009 P1 Garradd (February 2012): Date CDT/CST R.A. (J2000) Decl. Delta r El. Ph. M1 % Fore. Sky Motion Moon Phase Moon Mag. h m s "/min P.A. ( ) (Visual) All ephemeris data is calculated based on the Geographical location of the George Observatory, SE Texas, United States N, W

15 15 Overview of the Orbital Differences for Comets! Figure 6.1 Figure 6.2 P Periodic Comets C Non Periodic Comets Comet Garradd is the perfect example of a non periodic comet! The path is hyperbolic in nature. Comet 45P/Honda Mrkos Pajdusakova however is the perfect example of a periodic comet which is elliptical in nature. Figures 6.1 & 6.2 are of Comet C/Garradd 2009 P1 and Figure 6.3 below is off 45P. All images were obtained from the JPL Solar System Dynamics/Small Body Database Browser. Courtesy of NASA/JPL/CalTech Figure 6.3 Early Spring April 2012

16 16 Fainter Predominant Comets for Spring P/Giacobini - Zinner NEAT 246P/2010 V2

17 17 Fainter Predominant Comets for Spring 2012 (Continued) C/2009 F4 McNaught 78P/Gehrels 2 C/2011 Q2 McNaught