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Potential Secondary Target in the Anticenter: A 2M Sun Slightly Evolved Object

This study presents observations of a potential secondary target in the Anticenter direction, identified as a 2M Sun slightly evolved object. High-resolution spectroscopy reveals perturbed line profiles and a considerable photometric amplitude, suggesting the presence of dominant low-degree modes. Further analysis includes frequency analysis and whitening steps to determine the frequency content of the object.

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Potential Secondary Target in the Anticenter: A 2M Sun Slightly Evolved Object

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  1. HD 50844 • Poretti et al. (2005): • „Potential secondary target in the Anticenter dir.” • „a 2MSun, slightly evolved object” • „High-res. spectroscopy: perturbed line profiles: multiple star, or more probably a d Scuti showing high degree modes. The considerable photometric amplitude suggests the presence a of dominant low-degree mode.” Source: Poretti et al. (2005)

  2. Observations • Piszkéstető (MTA KTM CsKI) • d = 1m, f = 13500mm, RCC • Roper Scientific 1300B CCD • 20×20μm, 1340×1400 pix., 7’×7’ FOV • 2006. dec. – 2007. febr.: 7 nights • V filter

  3. Data reduction • IRAF (by the observers) • Comparison stars: • „bright” • „small” B-V diff. • C4 & C3 is OK • Photometry of min. 12 stars on every frame Image source: DSS POSS2

  4. Work with the data • Searching for other variables in the field: • 1 new variable! -> UCAC2 31295533 • Work with HD 50844 • Cut points affected by the changing weather (clouds) • Cut intervals with higher deviation (s) in C3-C4 • Final differential (V-C4) lightcurvesof the 4 used nights:

  5. Frequency analysis • PERIOD04 [Lenz, P., Berger, M. (2005)] • Discrete Fourier Transform • min. S/N=4 • Noise: max[A,B] • A: average amplitude of the whitened power spectrum in a ±10 c/d interval around the peak • B: average amplitude of the original power spectrum in the interval of [50:100] c/d (clearly beyond the frequency range of the star) • Analysis of weighted data & averaged data (60 sec) • Test of the program -> same results! • On the next slides: whitening steps with curve-fits to the observed data and a calculated continuous light curve

  6. Frequency content of HD 50844 2 dominant and 3 other frequencies were found HD 50844 could be a good secondary target.

  7. The „new” variable • RA (J2000): 06h 55m 11.7s • DEC (J2000):-01° 05’ 02.3” • Names:USNO-A2.0 0825-03492210 & UCAC2 31295533 from the Catalog of Astrometric Standards & The Second U.S. Naval Observatory CCD Astrograph Catalog • Is it really a „new” variable? -> YES! • ASAS Catalog of Variable Stars: no entry around this position • GCVS: no entry • VSX (International Variable Star Index): no entry • Personal communication with Dr. József Benkő: this object is not present in their database (too short period and too small amplitude to be traceable in the ROTSE-I data) • No sign of variability in Aladin.

  8. Analysis of UCAC2 31295533 • The same (and also the best) 4 nights were used in PERIOD04 • Full Fourier-analysis for the best 2 nights was also performed to compare results • Work with the weighted data • 30s points with a weight of 3, 20s points with a weight of 2, etc. • Much fainter (mV=12.8) then HD 50844 (mV=9.1), so it is harder to get accurate frequencies • The analysed light curves:

  9. Analysis - Whitening • steps for all the 4 nights and for only the „best” 2 nights • On the next slides: various fits to the observed light curves

  10. Frequency content of the new variable Four significant frequencies were found both in the 4 and the 2 day sample. Further observations are needed to determine values more precisely. • Could it be a possible CoRoT target? • For the Seismology field: NO (too faint) • Exoplanet field: YES (11.5<mV<16) • 32s integration time: OK (but there are only 500 windows per CCD for this) • 512s integration time: further simulations needed

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