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Research Article New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis

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Research Article New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis Hindawi Advances in Astronomy Volume 2019, Article ID 5641518, 18 pages https://doi.org/10.1155/2019/5641518 Research Article New Photometric Investigation of the Solar-Type Shallow-Contact Binary HH Bootis Jia-jia He 1,2,3 and Jing-jing Wang2,4 1 Yunnan Observatories, Chinese Academy of Sciences (CAS), P. O. Box 110, 650216 Kunming, China 2Key Laboratory of the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, P. O. Box 110, 650216 Kunming, China 3Center for Astronomical Mega-Science, Chinese Academy of Sciences, Beijing 100012, China 4China University of Petroleum-Beijing at Karamay, Anding Road 355, 834000 Karamay, China Correspondence should be addressed to Jia-jia He; [email protected] Received 17 September 2018; Accepted 12 December 2018; Published 6 February 2019 Academic Editor: Yue Wang Copyright © 2019 Jia-jia He and Jing-jing Wang. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricteduse, distribution, and reproduction in any medium, provided the original work is properly cited. Te short-period solar-type contact binary HH Boo was monitored photometrically for about 8 years. It is found that the CCD light curves in the �, �, �,and� bands obtained in 2010 are symmetric, while the multicolor light curves observed in 2011 and 2012 by several investigators showed a positive O’Connell efect where the maxima following the primary minima are higher than the other ones. Tis indicates that the light curve of the solar-type contact binary is variable. By analyzing our multicolor light curves with the Wilson-Devinney code (W-D code), it is confrmed that HH Boo is a W-type shallow-contact binary system with a mass ratio of � = 1.703(31) and a degree of contact factor of � = 12.86%(0.73%). By including 109 new determined times of light minimum together with those compiled from the literature, it is detected that the �−�diagram shows a cyclic oscillation with a period of �3 = 6.58(11) yr and an amplitude of � 3 =0.0018(1) d. Te cyclic change may reveal the presence of an extremely cool third body orbiting the central binary. 3 1. Introduction mass ratio �2/�1 = 0.633(42), �1sin � = 0.78(8) M⊙,and 3 �2sin � = 0.49(5) M⊙. Recently, a new period distribution HH Boo (GSC03472-00641, NSVS 5100852) was frst listed as � 11.m32 for EW-type binaries was given by Qian et al. [26, 27] based a star with a magnitude of = and a colour index on the orbital periods of 40646 systems given in VSX (the (� − �) 0.m45 of = in the TYCHO-2 Catalogue [24]. Te international variable star index [28]). Te period (0.319 d) variability of HH Boo was discovered by Maciejewski et al. of HH Boo is close to the peak of the distribution for EWs [2]. Tey reported that HH Boo was a EW-type binary system indicating that it is a typical EW-type binary. with a period of almost 8 hours from 214 data points collected Te frst photometric multicolor light curves in �, �, during 12 nights between April 19 and May 7, 2003. Te and � bands were published by Dal & Sipahi [16] that depths of the primary and secondary minima on their light Δ� 0.m50 0.m39 were obtained with 35 cm SchmidtCCassegrain type MEADE curves are � = and , respectively. Tey gave a telescope at the Ege University Observatory. As shown in preliminary ephemeris for the primary minimum as Figure 3 in their paper, their light curves showed a positive ���.� = 2452764.50965 (30) + 0.318618 (81) ×�. (1) O’Connell efect [29] where the maxima following the pri- mary minima are higher than the others. Te asymmetries Te spectrum of HH Boo is most similar to G5III type of the light curves may be caused by stellar dark-spot from their optical spectra in the blue. Te frst radial-velocity activities (e.g., [30]). Tey demonstrated that HH Boo is most studies of HH Boo have been done by Maciejewski & Ligeza likely a member of the A-type subclass of W UMa binaries [25]. Tey estimate the radii and the masses and derive a and derived absolute parameters of HH Boo. A continuous 2 Advances in Astronomy 1.0 0.8 HH Boo 0.6 0.4 G2V Rectifed Intensity 0.2 0.0 3300 3700 4100 4500 4900 5300 5700 Wavelength (angstroms) Figure 1: Normalized spectra of the eclipsing binary HH Boo from 3300 Ato5700˚ A,˚ observed on 2017 June 4 with the 2.16 m telescope at the Xinglong station of National Astronomical Observatories of China. Te lower pane is the spectrum data of G2V type star from the stellar spectral classifcation ([32]). decrease in the orbital period with a rate of ��/�� = −9.60 × 2.2. Multicolor CCD Photometric Observations. HH Boo was −7 −1 10 dyr was detected by them that was explained by either monitored photometrically in 13 nights from December 25, mass transfer from the secondary to the primary or mass loss 2010,toApril23,2018,byusingthenextthreetelescopes: from the system. the 1.0 m telescope at Yunnan observatories (YNOs-1m), HH Boo was later observed in 2011 and 2012 by using the 60 cm telescope at Yunnan observatories (YNOs-60cm), the0.40mMeade-LX200GPStelescopeatAnkaraUni- and the 85 cm telescope at Xinglong station of National versity Observatory [31] and new CCD light curves in Astronomical Observatories (Xinglong-85cm) in China. Te ���� bands were obtained. Teir light curves also show camera attached on Cassegrain focus of the 1.0 m telescope is positive O’Connell efect. By analyzing their ���� light DW436 CCD from Andor Technology, whose feld is about � � curves and published radial velocity data, they determined 7 .5 × 7 .5. Te CCD camera used on the 60 cm telescope is the parameters of the binary. Tey found that HH Boo is the same as that used on the 1.0 m telescope but has a larger � � W-subclass contact system and the asymmetry of the light feld of view, about 12 .5 × 12 .5. curves was interpreted by one cool star spot region located on Te frst complete �, �, �,and� light curves were the primary star (the hotter, less massive component). Tey obtained during three nights on December 25, 27, and 30, reported that the �−� diagram showed a cyclic variation with 2010, with PI 512 × 512 TE CCD camera mounted on aperiodof�3 = 7.39 yr and an amplitude of �3 = 0.00227 d. the Xinglong 85 cm telescope. Te efective feld of view � � of the photometric system is 14 .5 × 14 .5 at prime focus. Te flter system was close to the standard Johnson-Cousin- 2. Observations Bessel ����� CCD photometric system [34]. Te integration timeswere40s,30s,20s,and10sfor�, �, �,and� 2.1. Spectroscopy. To determine the spectrum of the solar- bands, respectively. For each band, about 200 images were type contact binary, the low-resolution spectrograms for HH obtained (� =197,� =196,� =196,and� =196).One Boo were observed by using the OMR spectrograph of the image of the � band is shown in Figure 2. GSC03472-00043 2.16mtelescopeatXinglongstationof National Astronomical and GSC03472-01201 whose coordinates and magnitudes are Observatories (Xinglong-2.16m) in China on 2017 June 4. We listed in Table 1 were chosen as the comparison and the check �� chose a slit width of 1. 8 and the Grism-14 with a wavelength star for HH Boo, respectively. Te comparison and check stars ranging from 3200 Ato7500˚ A([33]).Teexposuretime˚ are close enough to the variable that the range of air-mass is 15 min. Reduction of the spectra was performed by diference between both of them was very small. Terefore, an using IRAF packages (IRAF is supported by the National extinction correction was not made. Te PHOT task (which Optical Astronomy Observatories (NOAO) in Tucson, measures magnitudes for a list of stars) in the IRAF aperture Arizona http://iraf.noao.edu/iraf/web/iraf-homepage.html), photometry package was used to reduce the observed images, including bias subtraction, fat-felding, and cosmic-ray including a fat-felding correction process. removal. Finally, the one-dimensional spectrum was ex- Te CCD photometric data obtained on December 25, 27, tracted. Using the winmk sofware (http://www.appstate and 30, 2010, in �, �, �,and� bands are listed in Tables 2–5 .edu/∼grayro/MK/winmk.htm), the normalized spectra are and shown in Figure 3, respectively. Te complete CCD light displayed in the upper pane of Figure 1. On the basis of the curves in the four bands with respect to the linear ephemeris, stellar spectral classifcation ([32]), we determined its spectral ���.� (���) = 2455556.34396 + 0d.318666208 × �, type to be G2V, which is similar with G5III obtained by [2]. (2) Advances in Astronomy 3 Figure 2: One CCD image about HH Boo obtained by 85 cm telescope at Xinglong station of National Astronomical Observatories (Xinglong- 85cm) in China including variable (V), comparison (C), and check stars (K). −2.2 −2.1 Dec. 25, 2010 Dec. 27, 2010 Dec. 30, 2010 −2.0 −1.9 −1.8 −1.7 −1.6 −1.5 ΔＧ −1.4 −1.3 −1.2 −1.1 −1.0 −0.9 −0.8 −0.7 56.32 56.36 56.40 58.32 58.36 58.40 61.30 61.35 61.40 61.45 HJD(2455500.0+) B+0.1m V R-0.1m I-0.2m Figure 3: CCD photometric observations for HH Boo in the �, �, �,and� bands observed on December 25, 27, and 30, 2010 by the 85 cm telescope at Xinglong station of National Astronomical Observatories (Xinglong-85cm) in China. Table 1: Coordinates and magnitudes of HH Boo, the comparison, and the check stars.
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