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Does distance matter?

Started by TriDitty
Default_user
over 6 years ago

I've noticed that some of the stars have a very detailed graph with nearly no noise at all. It almost looks like someone drew the graph instead of compiling the data from a far away star.

Is this due to some stars being much much closer than others and could you add the distance between stars to the info provided for each graph?

Default_user
over 6 years ago

We don't know the exact distances to the Kepler stars. if we knew we would definitely add that information to the info we give. Only for a handful of Kepler stars do we have accurat distances measured. Most of the Kepler stars are within 600 to 3,000

light years from the Earth. So distance matters in terms of the magnitude of the star, how bright we see it which has some impact on the light curve, because a star with the absolute magnitude will be fainter in apparent magnitude (how much light we observe from it) as you move it further from the Earth.. Brighter stars tend to be more variable because we can see the variability because the signal-to-noise is higher in the measurements. I would say what you're seeing is mainly natural variability in the brightnesses of the star. Kepler has found the most Sun-like stars are twice as variable as our Sun. Also some of what you're seeing is the scale of the light curve, for the flatter light curves the interface zooms in on them so you see the error bars more than on light curves where the brightness changes are larger.

I hope this helps answer the question,

~Meg

Default_user
over 6 years ago

Meg, how are distances calculated?

Default_user
over 6 years ago

The parallax effect - so we don't have many stars that have many measurements - Hipparcos was a satellite that measured this some stars and made a catalog but not many of those stars were in the Kepler field. A new ESA mission Gaia that should launch in 2013 will have higher precision and measure this for more stars.

~Meg

Default_user
over 6 years ago

Thnx, that is exactly what I was asking. I was trying to figure out if there was a corrilation between their visable magnitudes and the noise/variance and I definately was curious why it seemed like the bright ones had more variance in the graphs. Heck, to make this project harder, the bigger and brighter the star, the less light lost during a transition and the less obvious the transition appears to an barely trained newbie like me.

Now I am going to really be imagining patterns;)

I'll try to tone them down though. Ya know, keep them down to less than fifty per graph:)

Default_user
over 6 years ago

TriDitty:

Thnx, that is exactly what I was asking. I was trying to figure out if there was a corrilation between their visable magnitudes and the noise/variance and I definately was curious why it seemed like the bright ones had more variance in the graphs. Heck, to make this project harder, the bigger and brighter the star, the less light lost during a transition and the less obvious the transition appears to an barely trained newbie like me.

Now I am going to really be imagining patterns;)

I'll try to tone them down though. Ya know, keep them down to less than fifty per graph:)

Most light curves don't have transits in them, so if you're typically marking 50 or see 50 events per light curve, you're marking many false positives. I'd look around at people's collections and our site guide for examples of transits.

~Meg

Default_user
over 6 years ago

mschwamb:

TriDitty:

Thnx, that is exactly what I was asking. I was trying to figure out if there was a corrilation between their visable magnitudes and the noise/variance and I definately was curious why it seemed like the bright ones had more variance in the graphs. Heck, to make this project harder, the bigger and brighter the star, the less light lost during a transition and the less obvious the transition appears to an barely trained newbie like me.

Now I am going to really be imagining patterns;)

I'll try to tone them down though. Ya know, keep them down to less than fifty per graph:)

Most light curves don't have transits in them, so if you're typically marking 50 or see 50 events per light curve, you're marking many false positives. I'd look around at people's collections and our site guide for examples of transits.

~Meg

Thnx... I was just kiding about the fifty per graph thing.

Default_user
over 6 years ago

Thnx... I was just kiding about the fifty per graph thing.

:-)

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