domingo, 16 de agosto de 2020

Search Correlation rotation period versus diameter C/2020 F3 NEOWISE .

Based in next telegram :

ATEL #13945                                                          ATEL #13945


Title:  Rotation of Comet C/2020 F3 (NEOWISE)
Author: Michal Drahus (Jagiellonian University in Krakow), Piotr Guzik
                (Jagiellonian University in Krakow), Andrew Stephens (Gemini Observatory),
                Steve B. Howell (NASA Ames Research Center), Stanislaw Zola (Jagiellonian
                University in Krakow), Mikolaj Sabat (Jagiellonian University in Krakow),

                Daniel E. Reichart (University of North Carolina at Chapel Hill)The observed morphological evolution implies a rotation period of 7.58 +/- 0.03 hr with no obvious temporal changes or deviations from a simple rotation state over the reported time interval. This result is consistent with an earlier value of 7.5 +/- 2.3 hr reported by Masi 2020 (CBET 4816). 

I decided to establish a correlation period of rotation - diameter of the nucleus, it is known that the greater the diameter the rotation of the comet nucleus is slower, and the smaller the diameter the rotation is faster, the average rotation period of many comets is approximately about 15 hours, based on Whipple's work.

In the case of comet C / 2020 F3 NEOWISE the P (rot) = 7.5 hours, analyzing other comets such as 6 P / D'Arrest, P (rot) = 7.2 h (Lowry, Weissman 2007), and a D (km) = 1.6 km (Ferrin 2009), results in a nuclear radius of Rn = 0.8 kms, another comet similar in the period of rotation to F3 NEOWISE is comet 46 P / Wirtanen, with D (km) = 0.9 kms (Fink V. et at. 1997), with a P (rot) = 7.6 h (Ferrin 2009), looking for articles with references, the most interesting is that of Sosa / Fernandez, who establish the following equation 1.0:


log D (km) = 1.5 - 0.13 * H ........... (Sosa & Fdez)


Checking this formula 1.0 I applied it to the previous results, and it was not a good fit, so I decided to apply a new personal adjustment, which is the following 1.1:


log D (km) = 1.3 - 0.13 * H ............... (Navarro)


finding a comet diameter of 0.94 kms, a value that is more in line with reality.


Another new formula that relates the activity index with the gas production rates is the following 1.2:


log Q (C2) / log Q (H2O) = - n ............... (Navarro)


Coefficient of variation of the rate of increase in brightness 1.3:


K = d (n) / d (r)


r heliocentric distance

n rate of increase in brightnes

viernes, 7 de agosto de 2020

Update Light Visual Curve C/2020 F3 NEOWISE

New update of the visual light curve of comet NEOWISE, based on 798 observations of the comet, from the COBS database, my analysis includes the calculation of the photometric parameters of the comet before and after perihelion. The first conclusion shows, based on the activity index n, that the comet has been more active at the gas / dust level in the pre-perihelion, with an index of R ^ (- 5.45), in the post-perihelion the comet, has a much lower index or rate of increase in brightness than R ^ (- 4.20), this gives a coefficient of variation of n, based on my personal formula: [Navarro Formula .... K = R ^ (n1- n 2) , K = R ^ (-1.25)] where n1 is the pre-perihelion index and n2 is the post-perihelion index. The post-perihelion adjustment is quite close to the average line that I have calculated, but there is an overestimation of 0.5 to 1.0 magnitudes in the measurements on the general curve. The general formula of the comet is m0 = 7.0 and n = 12.1, later in this blog I hope to refine the final diameter of the NEOWISE comet, as well as the rates of production of water gas and compare them with the real ones.


viernes, 10 de julio de 2020

Light Visual Curve C/2020 F3 NEOWISE

I just updated the visual light curve of Comet C / 2020 F3 NEOWISE, it has been a surprise for all amateur and professional astronomers, the ephemerides indicated a maximum visual magnitude close to +8, but currently it shines with magnitude +1.5, we are talking about An important start of activity at the nuclear level that has increased + 6.5 visual magnitudes, my preliminary calculations indicate an absolute magnitude of m0 = + 7.3, this is compatible according to my analysis with a core diameter of ~ 2.5 kms approximately, and a radius nuclear of Rn ~ 1.2 kms. , the formula that dominates the comet's brightness law is: m1 = + 7.3 log (D) + 11.6 log (r) So the activity index n = 4.6, with a heliocentric-photometric law of R ^ -4.6, compatible with the equations of log Q (C2) = - n * log (r) given by Morris and Hanner 1986, like than with water. The light curve is based on 173 visual observations, from COBS plus the own sources that send me observations, from here to thank W. Souza and S.Yoshida for their personal contributions to my analyzes. The approximate calculation of the production rate of water Q (H2O) for this comet indicates about 10 tons per second, based on the reduced light curve data.

viernes, 8 de mayo de 2020

Analysis C/2020 F8 SWAN

In my differential analysis, the comet shows 3 different brightness laws with 3 changes in photometric parameters: 1 law R = 0.87 au 2 law R = 0.77 au 3 law R = 0.67 au the equal difference in the variation of the heliocentric distance of the comet from d (r) ~ 0.10 au, with an increase in brightness and later a decrease in brightness, there is an outburts in DJ = + 2450000 + 8965, of approximately 2 magnitudes: d (m1) / d (r) = 2.0 / 0.10 = 20 mag / au My hypothesis is that the comet has undergone a sudden and brief increase in brightness due to an unusual increase in the comet's dust and gas production rates that has lasted approximately less than a week, the brightness production rate should stagnate and continue even steady rhythm without going down.

viernes, 24 de abril de 2020

Evolution of the fragmentation of the comet ATLAS from April 20 to 23, 2020 based HST images .

Original observing program: 16111 - Jewitt, David - University of California - Los Angeles Breakup of Long-Period Comet C / 2019 Y4 (ATLAS) Images HST Evolution of the fragmentation of the comet ATLAS from April 20 to 23, 2020, in the images of April 20, 2020, 4 bright fragments called ABCD are observed, after 72 hours the comet only shows 2 main AYB fragments, and several mini fragments Comments, I am in the process of analyzing the images, I hope to present my results soon, in this blog.

miércoles, 22 de abril de 2020

C/2019 Y4 ATLAS HST

C/2019 Y4 ATLAS by HUBBLE SPACE TELESCOPE Original observing program: 16111 - Jewitt, David - University of California - Los Angeles Breakup of Long-Period Comet C/2019 Y4 (ATLAS) Processing J.P.Navarro

viernes, 27 de marzo de 2020

Light visual curve comet C/2019 Y4 ATLAS ( News )

My last analysis of the visual light curve of the comet C / 2019 Y4 ATLAS, confirms the prediction I made a few days ago in the group, about the change in the evolution of the comet's brightness, in the heliocentric range 1.6 < r < 1.4 au, in my Cometary Astrophysics blog, you can see the change in the rate of increase in brightness, which occurs at the distance R = 1.67, on March 21, 2020, as I predicted a few days ago , the graph based only on visual observations, you can see the green line that shows an activity index or rate of increase in brightness of n = 40.0 a law of brightness (R ^ -16), however there is a change in R = 1.67 au, as I first predicted in this group, a few days ago, occurred on the date of March 21, 2020, confirming my forecasts, that it is a possible fragment or twin comet to comet C / 1844 Y1, since that the orbital elements have a fairly exact match, my bet, is that the eater ta C / 2019 Y4 ATLAS, it is a brother or twin comet, from the date of March 21, 2020 at R <1.67 au, the comet suffers a drop in its activity index, probably due to a very high increase in water production rate, being the volatil component that totally dominates the sublimation of ice in the comet, with n = 15.2 and R ^ -6.1, it is almost an almost complete shutdown of volatiles, so the comet, it should not increase its brightness and visual magnitude much further in the future. Visual magnitude max. perihelion m1 = -9.6

domingo, 22 de marzo de 2020

Search Correlation rotation period versus diameter C/2020 F3 NEOWISE .

Based in next telegram : ATEL #13945                                                          ATEL #13945 Title:  Rotation of Comet C/2020 F...