KIC 3448777 Unlisted RR Lyrae ab

Started by Tom128
Default_user
almost 8 years ago

Reminds one of an RR Lyrae pattern. Not listed if it is.

Default_user
almost 8 years ago

Amplitude is too low to be an RR Lyrae type AB, but could be an RRL type C. Right spectral class. Ragged nature of light curve however casts some doubt and suggests possible contamination but background field looks clear.

UPDATE: Oh - I know why the light curve is so crappy and not because of contamination - Q2 was imaged by mod.out 2.3 and therefore a victim of the #fp16 glitch!

Default_user
almost 8 years ago

Very interesting Kianjin. Does that mean the RR Lyrae-like pattern is a product of the glitch as well ?

Default_user
almost 8 years ago

No, I was pretty sure the RRL pattern is in the star itself, just masked by errors in photometry and/or postprocessing. Here's how the undetrended but Kepler processed light curve looks like, Q1 to Q3:

It's strange that Q1 doesn't show any pulsations. Q2 is definitely distorted by the fp16 problem, but even Q3 has some funky distortions of its own.

So what I did was to take the raw flux from Q3 alone, detrended it myself and here's what I got - an RRL-like light curve complete with Blazhko modulation!

I'm pretty sure this is what the star should look like, and here's the final phased waveform:

I would wager a guess that it's an RR Lyrae type C. That's because the amplitude of the pulsations is less than 1%, although it has all the other characteristics, spectral class, Blazhko modulation of typical RR Lyraes.

So in the end, you were right, Tom, well done, and a great find!

Default_user
almost 8 years ago

Outstanding analysis Kianjin and we netted an unlisted one as well! KID 3448787

Default_user
almost 8 years ago

Just a quick note to say I've emailed a friend who is one of the authors on the Blenko list : http://arxiv.org/abs/1007.3928 - I'll report back if I get any response.

Default_user
almost 8 years ago

Good news! I've heard back from our friends in the Kepler team, and this star is interesting and indeed new to them, so this is another #discovery for Planet Hunters! Congratulations, Tom128 for spotting it, and Klanjin for the analysis. They're going to do a detailed analysis - indeed, they've already started - and keep us informed. Obviously if it makes a paper then full credit will go to you two.

Some extra details; the reason that the variation appears and disappears between quarters might be because it's a background star; this would explain the small amplitude and if the processing used on different quarters included different parts of the image then that would explain why it comes and goes.

They also say "Any new RRLs - especially the modulated ones - are of great value and very much appreciated! Kepler provides excellent light curves and delivers surprising new discoveries on #RRLyrae stars." so do tag anything you find.

As Robert Szabo, one of the scientists says : 'Congratulations to this precious discovery'.

Default_user
almost 8 years ago

Great find.

Default_user
almost 8 years ago

I give Kianjin the lion's share of credit for this find. He not only taught us about RR Lyrae stars and Blazhko modulation on the Science board and what to look for in the periodogram, Kianjin also takes the time to instruct us on promising finds posted here at Planet Hunters. Thanks Kianjin!

Default_user
almost 8 years ago

Indeed, I'm also glad I don't have to detrend by hand now thanks to his scripts :-)

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