Meteoric rains for “Juilletists”-Vigie-Ciel

Are you one of the “Julyists”? However, This kind of tourists who saw fit to take their vacation during the first period of school holidays? In addition, And you just realized by reading your favorite scientific magazine that the maximum activity of the rain of stars. However, shooting the famous “Perseids” takes place around August 12? Therefore, Don’t panic! Nevertheless, This year. For example, the peak of the Perseids (and even THE picsto read in a future article) will (have) place while the moon will be almost full. Similarly, And several sources of meteors of less activity. Furthermore, but just as interesting to observe, are active at the end of July, when the moon is new, therefore absent from the sky! Consequently, So don’t cry anymore, the “Julyists” are also their rains!

Delta-Aquariides Sud. Meanwhile, Alpha-Capricornides, Austrinid Pisces: the barbaric names of meteoric rains “juilletists”-vigie-ciel the rains of the “Juilletists”

If the terms delta-Aquariides Sud (SDA), alpha-Capricornides (CAP) et Pisces Austrinides (PAU) Do not mention anything, it’s normal. Similarly, These names awaken sweet memories only to astronomers with more in -depth knowledge in the streams of shooting stars. Meanwhile, And they correspond to Three most active meteoric rains at the end of July. Moreover, By an effect of perspective. For example, all the shooting stars of the same rain seem to come from the same point from the sky, the radiant. In addition, Whose position determines the name of the meteor rain. Thus, that of the Perseids is located in the constellation of Perseus during the maximum. According to this same logic. the radiant of the southern delta-aquariides is located in the Aquarius (Aquarius In Latin), that of alpha-capricornides in … Capricorn (that’s it, you are starting to take the fold) and that of the meteoric rains “juilletists”-vigie-ciel austrinid pisces in … southern fish (ok, we grant you, it was less obvious for that one, see Figures 1 and 2). Some of these rains. such as alpha-capricornides, have already been active since the beginning of July, giving birth to a shooting star per hour. But Their activity will continue to increase to peak at the very end of the month: the maximum of the Pau is scheduled for July 28et That of the SDA. CAP takes place on 30.

A complex of sources. about fifteen shooting stars per hour

In reality, the rains of meteor active in this regions are much more numerous than the meteoric rains “juilletists”-vigie-ciel three aforementioned, since the UAI (International Astronomical Union) has listed there a dozen sourcesof various origins. They are therefore part of a large complex (Figure 2) which will be the source of many meteors. If the most active rains is undoubtedly that of the southern delta-aquariides. but the combined activity of all sources should represent a Fifteen shooting stars observable per hour in the middle of the (00 p.m. you, 02 hours, French local time), at the end of July.

Les Delta-Aquariides South: the 5^th meteoric rains “juilletists”-vigie-ciel most active meteor rain of the year

The most active of them is therefore that of Delta-Aquarids Sud : although it is relatively little known. son zhr (Zenithal Hourly Rate) however reached 25 during the peak (July 30) and even remains at levels close to 20 for almost 48 hours around the maximum, which places it in 5^th position of the most active meteoric rains of the year ! Active from July 12 to August 23. this is one of the main providers of the summer, and the star at the origin of these meteors is not yet clearly identified, even if it could be the comet* C/1490 Y1 (whose fragmentation gave birth to 96p/Machholz and the asteroid* 2003 EH1, sources, among other quadrantids and diurnes).

The other meteoric rains have periods of activity extending over almost all summer. but lower activity rates (ZHR of around 5 during the maximum for CAP and Pau, and rather from 2 to 3 for all other sources of the active meteoric complex). It is the cumulative activity of these rain. combined with that of the antihelian source (Ant) which sits in the middle of the complex (Figure 1), which should delight “Julyist” astronomers! Especially since the moon is new on July 24: on the night of July 29 to 30, the crescent moon sets around 11 p.m. (local), while the Aquarius will be just rising above the east-south-east horizon. Our natural satellite will therefore be no discomfort to admire these slow -at -medium -slow speed meteors (meteoro entrance speed of 23 km/s for CAP. 30 km/s meteoric rains “juilletists”-vigie-ciel for Anti, 35 km/s for the Pau, and 41 km/s for SDA), and which can sometimes be very bright!

And why not also observe some Perseids?

The ideal. to make the most of the show, is to focus your field of vision on the constellation of fish, by shifting by a dozen degrees east of Saturn. Thus. you will be able to see more meteors, and above all, for the most motivated, you can distinguish their original radiant if you draw them on a dedicated map (so -called gnomonic card). And small bonus: the activity of the Perseids will also have started. at the end of July, and their ZHR should already be between 5 and 10, which is far from negligible. And by observing this celestial field, you can observe half a diza per hour!

One way like any other to make a foot-of-our “Augustians”!

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meteoric rains “juilletists”-vigie-ciel