Proposal #375

Comments

(3000) Sebastián Otero — June 30, 2023, 5:22 p.m.

Rodney, both the magnitude and the amplitude seem to be wrong. VSX lists it as having Kp= 14.49 with an amplitude of only 0.004 mag.
This is a Kepler variable only. Nothing to do from the ground due to the small amplitude. We can derive V= 14.61 from Gaia DR3.
It has a V= 12.70 mag. star 16.5" away which is listed as a SB1 with P= 605.74 d. in Gaia DR3 too.
Another Kepler paper gives a period of 2.479 d. instead of the 22.208 d. in VSX.
Is it possible that you misidentified the target? Where have you taken the variability information from?

(2181) Rodney Howe — July 5, 2023, 4:58 p.m.

Hi Sebastian,

Not sure about Gaia DR3 star, and the other Kepler paper with 2.479 day period. The reference I used for this comes from here:
https://www.researchgate.net/publication/341133559_Solar-type_Stars_Observed_by_LAMOST_and_Kepler
Also, from the SIMBAD query. https://simbad.u-strasbg.fr/simbad/sim-basic?Ident=KIC10414643&submit=SIMBAD+search
Any suggestions on how we might get ground based data on these KIC stars with similar rotation periods as the sun, would be interesting, I think.
I posted some of this on the Feb 2023 Solar Bulletin: https://www.aavso.org/sites/default/files/solar_bulletin/AAVSO_SB_2023-02.pdf

Rodney

P.S. And the Jupyter Lab program from the NASA Kepler KIC data for the 12 quarter:
# https://github.com/spacetelescope/notebooks/blob/master/notebooks/MAST/Kepler/kepler_searching_for_data_products/kepler_searching_for_data_products.ipynb

import lightkurve as lk
import matplotlib.pyplot as plt
#%matplotlib inline #only good with Jupyter
%matplotlib inline

search_result = lk.search_lightcurve('KIC 10414643', mission='Kepler')
search_result
search_result[0]
for column in search_result.table.columns:
print(column)

# import numpy, which we will use to find the desired index in the table
import numpy as np
#quarter2_index = np.where(search_result.table['observation'] == 'Kepler Quarter 2')[0]
#search_result[quarter2_index]

search_result_q2 = lk.search_lightcurve('KIC 10414643', mission='Kepler', quarter=12)
search_result_q2

lc = search_result_q2.download_all()
lc
lc.plot();
#print ("lc = ",lc)

lc_collection = search_result[:9].download_all()
lc_collection

# Create a larger figure for clarity
fig, ax = plt.subplots(figsize=(20,5))
# Plot the light curve collection
lc_collection.plot(ax=ax);

fig, ax = plt.subplots(figsize=(20,5))
for lc in lc_collection:
lc.normalize().plot(ax=ax, label=f'Quarter {lc.quarter}');

pixelfile = lk.search_targetpixelfile('KIC 10414643' , mission='Kepler') [9].download()
lc = pixelfile.to_lightcurve(method="pld").flatten()
period = lc.to_periodogram("bls").period_at_max_power
lc.fold(period).truncate(0.10, 0.15).scatter();

print ("Period = ",period)
print ("Pixelfile = ",lc)
lk.show_citation_instructions()

(3000) Sebastián Otero — July 5, 2023, 9:28 p.m.

Hi Rodney, the paper you provide shows a Kepler light curve that only shows flux variations at less than 1% level, consistent with the VSX parameters.
Also, SIMBAD does not provide any optical magnitude. Only JHK magnitudes 13.37, 13.03 and 12.99. You gave a range 12.9 - 13.3 and these figures seem to be the K and J magnitudes given in SIMBAD and truncated. They are not visual magnitudes and they are different passbands not maximum and minimum values.

To search for Kepler objects with periods to that of the Sun, you can use VSX.
Click on "More" twice to get extended search options.
Write "KI%" as the star name.
Select a period range. I selected 15 to 35 d.
Choose "Rotational variables" in the grouping menu.
17546 stars meet such criteria. We can't filter by amplitude and VSX results are truncated to 5000 rows so you will have to download the csv file to get all results.
In the csv file you will be able to create a separate column for the amplitudes and then only select the ones with an amplitude that makes them worth observing from the ground.
Keep in mind that tha vast majority of objects will have too low amplitudes and might not be worth observing. What value do you plan to add for stars that have been observed with millimagnitude precission by Kepler?

(2181) Rodney Howe — July 5, 2023, 10:16 p.m.

Hi Sebastian,

Thanks for this clarification. I agree, not going to value any precision better than Kepler. I was thinking perhaps ground based photometry might be useful for these stars, but I doubt it.

Rodney

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