Asteroids rotation period
Download
1 / 9

Zachariadou - PowerPoint PPT Presentation


  • 222 Views
  • Uploaded on

Rotation period. Study the photometric curve. Shape. Is it binary?. Asteroids Rotation Period. spectroscopy. Surface composition. Observations reveal:. Time-dependent brightness variations. Rotation period of the asteroid around its axis. Due to:.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Zachariadou' - Angelica


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Asteroids rotation period l.jpg

Rotation period

Study the photometric curve

Shape

Is it binary?

Asteroids Rotation Period

spectroscopy

Surface composition


Slide2 l.jpg

Observations reveal:

Time-dependent brightness variations

Rotation period of the asteroid around its axis

Due to:

Different reflectivity across the asteroid

Non spherical shape of the asteroid

Average rotation period: 10 h

Typical brightness variation : 0.2 mag

Fast rotators period: 2 h

Slow rotators period: few weeks

Most rotators period: 7 h –30 h


Slide3 l.jpg

Asteroid Rotation Period Determination

Non spherical shape-

rugby ball

Time-dependent brightness variations

for most asteroids are due to:

Cross section changes (as seen by the Earth)

Light reflected towards us varies-

Brightness appears to vary


Slide4 l.jpg

Asteroid Rotation Period Determination

Shape is 180 degrees symmetrical around an axis perpendicular to its greatest dimension

Rugby-ball shaped asteroid

Other side of the asteroid

max

max

min

min

max

same side of the asteroid-full revolution


Slide5 l.jpg

Asteroid Photometry

Magnitude

Intensity

Magnitude system

The scale that traditionally has being used to denote the brightness of an object

brightness

Based on the eye

Brighter stars : 1st mag

Dimmest stars : 6st mag

The intensity becomes 10 times larger every -2.5 magnitudes eg. 6st mag staris 100 times fainter than1st mag star

Real intensity:

Or in mathematics :


Slide6 l.jpg

Known brightness

Magnitude

Intensity

Asteroid photometry process:

  • Every certain interval of time take a picture

  • in each picture measure the signal from the asteroid

  • Measure the signal from at least onecomparison star of similar color in the vicinity of the asteroid

Is the comparison star

variable?

Pick 2 or more comparison stars and use the average intensity


Slide7 l.jpg

Asteroid photometry process-continued :

  • Calculate Δm from each measurement (we need to know the brightness variation and not the actual brightness of the asteroid )

  • Plot Δm vs time (eg. pictures are 3min apart)

  • Calculate the period by measuring the time between consequitive maxima or minima of the same amplitude


Slide9 l.jpg

Exercise procedure

Short period : < 4h

Bright enough

Be observable most of the night

  • Pick an asteroid

  • Plan an observation

  • Submit a request to the telescope

  • Analyse the data

List of asteroids

1727 Mette

Cartes du Ciel

Avis


ad