\documentstyle[twoside, epsf]{article}

\input ibvs2.sty

\begin{document}
\IBVShead{6025}{25 June 2012}

\IBVStitletl{$\mathbf VR_{\mathrm c}I_{\mathrm c}$ optical light curves of V1647 O\lowercase{ri} during}{ the continuing second outburst}


\IBVSauth{Semkov, E. H.; Peneva, S. P.}

\IBVSinsto{Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences,
              72 Tsarigradsko Shose blvd., BG-1784 Sofia, Bulgaria, 
e-mail: esemkov@astro.bas.bg, speneva@astro.bas.bg}


\SIMBADobj{V1647 Ori}
\IBVStyp{ FUor? EXor? }
\IBVSkey{optical photometry}
\IBVSabs{Results from VRcIc photometric observations during the}
\IBVSabs{second outburst of the pre-main sequence object V1647 Ori}
\IBVSabs{are presented. The photometric data show a continuous slight}
\IBVSabs{decrease in brightness during the period of observations.}
\IBVSabs{In the meantime the star becomes redder with decreasing of}
\IBVSabs{brightness.}


\begintext

The outburst of the pre-main sequence (PMS) star V1647~Ori was discovered by the amateur astronomer Jay McNeil in January 2004 (McNeil 2004).
The star showed an increase of its optical brightness by around 5 mag beginning from November 2003 till February-March 2004 (Brice\~{n}o et al. 2004). 
V1647 Ori remained in a state of maximum light about two years, then its brightness declined to the pre-outburst level (K\'osp\'al et al. 2005).
The optical and infrared light curves of V1647~Ori during the outburst are well studied and documented (Acosta-Pulido et al. 2007, Fedele et al. 2007, Aspin \& Reipurth 2009, Garc\'ia-Alvarez et al. 2011).
During the outburst V1647~Ori exhibited a strong emission spectrum in the optical and near-IR, typical for eruptive PMS stars of EXor type (Herbig 2008).
However, the spectral structure in the infrared and the relatively long outburst give some reasons to classify the star as a FUor (Aspin et al. 2008).

A second outburst of the star was registered in 2008, when its brightness increased again to the level of the first eruption (Itagaki et al. 2008, Kun 2008).
The optical and infrared follow-up observations show that the star and the surrounding nebula appear photometrically and morphologically similar to the first outburst (Aspin et al. 2009).
Only a few papers publishing data from optical and infrared photometric observations during the second outburst have appeared until now (Kaurav et al. 2010, Garc\'ia-Alvarez et al. 2011, Aspin 2011).
During both outbursts V1647~Ori showed a strong emission H$\alpha$ line with blueshifted absorption (P Cygni profile) while in the time between the outburst the H$\alpha$ line weakened and the blueshifted component disappeared (Aspin \& Reipurth 2009, Aspin 2011). 
A correlation between the X-ray luminosity and $I_{\mathrm C}$ magnitude during the two outbursts were found by Teets et al. (2011). 

The present paper is a continuation of our photometric study of the star during the first outburst (Semkov 2004, 2006).
We present new $VR_{\mathrm C}I_{\mathrm C}$ photometric data of V1647~Ori in the period November 2008 -- April 2012.
A part of our data (from 2008 Nov 20 till 2010 Aug 20) are presented in Fig. 1 of Garc\'ia-Alvarez et al. (2011).
Our data were obtained in two observatories with three telescopes: the 2-m RCC and the 50/70-cm Schmidt telescopes of the National Astronomical Observatory Rozhen (Bulgaria) and the 1.3-m RC telescope of the Skinakas Observatory of the Institute of Astronomy, University of Crete (Greece).
The technical parameters and chip specifications of the CCD cameras used are summarized in Table 1.
All frames were taken through a standard Johnson--Cousins set of filters.
Aperture photometry was performed using DAOPHOT routines.

The $VR_{\mathrm C}I_{\mathrm C}$ comparison sequence reported in Semkov (2006) was used as a reference.
In order to minimize the light from the surrounding nebula, all frames were reduced using the same aperture of $2\farcs5$ radius and the background was taken between radii 20$\arcs$ and 25$\arcs$.
The typical errors in the reported magnitudes are in the range $0\fmm01$-$0\fmm03$ ($I$ and $R$) and $0\fmm02$-$0\fmm05$ ($V$) for observations made with 2-m RCC and 1.3-m RC telescopes and in the range $0\fmm02$-$0\fmm04$ ($I$) and $0\fmm02$-$0\fmm06$ ($R$) for observations made with the Schmidt telescope.
The results from our CCD photometric observations are given in Table 2.
The table contains date, the Julian date, the $I_{\mathrm C}$, $R_{\mathrm C}$ and $V$ magnitudes.
Fig. 1 shows the $V$, $R_{\mathrm C}$ and $I_{\mathrm C}$ light curves of V1647~Ori for the period of our photometric observations.
Typical error bars for each filter are shown at the left.

\begin{table}
\centerline{Table 1. CCD cameras and chip specifications}
\vskip 2mm
\begin{center}
\begin{tabular}{llllll}
\hline
\noalign{\smallskip}  Telescope & CCD type & Size & Pixel & Field & RON \\
\noalign{\smallskip}  & & & size [$\mu$m]& & {\small [ADU/rms]}\\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
2-m RCC & VersArray 1300B & $1340{\times}1300$ & 20 & $5.\mkern-4mu^\prime6{\times}5.\mkern-4mu^\prime6$  & 2.8 \\
1.3-m RC & ANDOR DZ436-BV& $2048{\times}2048$ & 13.5 & $9.\mkern-4mu^\prime6{\times}9.\mkern-4mu^\prime6$ & 5.3 \\
50/70-cm Schmidt & STL-11000M &  $4008{\times}2672$ & 9 & $72^\prime{\times}48^\prime$ & 13 \\
50/70-cm Schmidt & FLI PL16803  & $4096{\times}4096$ & 9 & $74^\prime{\times}74^\prime$ & 9 \\
\noalign{\smallskip}
\hline
\end{tabular}
\end{center}
\end{table}


\begin{table}
\centerline{Table 2. Photometric observations of V1647~Ori}
\vskip 2mm
{\small
\begin{center}
\begin{tabular}{lllllll}
\hline
\noalign{\smallskip}
Date & J.D.(245...)  &  $I_{\mathrm C}$    & $R_{\mathrm C}$ & $V$  & Tel.& CCD \\
\noalign{\smallskip}
\hline
\noalign{\smallskip}
2008 Nov 20 & 4791.387 & 14.57 & 16.23  &  $-$  & Schmidt & STL11000\\
2009 Jan 11 & 4843.263 & 14.72 & 16.73  &  $-$  & Schmidt & STL11000\\
2009 Mar 24 & 4915.262 & 14.67 &  $-$   &  $-$  & Schmidt & STL11000\\
2009 Apr 16 & 4938.277 & 14.65 &  $-$   &  $-$  & Schmidt & STL11000\\
2009 Aug 21 & 5065.562 & 14.53 &  $-$   &  $-$  & Schmidt & FLI\\
2009 Oct 09 & 5115.453 & 14.67 & 16.69  &  $-$  & Schmidt & FLI\\
2009 Oct 28 & 5133.419 & 14.52 & 16.43  &  $-$  & Schmidt & FLI\\
2009 Nov 19 & 5155.411 & 14.63 & 16.64  &  $-$  & Schmidt & FLI\\
2009 Nov 20 & 5156.473 & 14.61 & 16.55  &  $-$  & Schmidt & FLI\\
2009 Nov 21 & 5157.474 & 14.66 & 16.64  &  $-$  & Schmidt & FLI\\
2009 Nov 25 & 5161.497 & 14.68 & 16.76  & 18.32 & 2m RCC  & VA\\
2010 Mar 11 & 5267.277 & 14.54 & 16.49  & 18.13 & 2m RCC  & VA\\
2010 Mar 12 & 5268.324 & 14.61 & 16.60  &  $-$  & 2m RCC  & VA\\
2010 Aug 12 & 5420.616 & 14.91 &  $-$   &  $-$  & 1.3m RC & ANDOR\\
2010 Aug 20 & 5428.613 & 14.93 & 17.12  &  $-$  & 1.3m RC & ANDOR\\
2010 Aug 24 & 5432.588 & 14.87 & 17.09  &  $-$  & 1.3m RC & ANDOR\\
2010 Aug 25 & 5433.598 & 14.85 & 17.07  &  $-$  & 1.3m RC & ANDOR\\
2010 Sep 20 & 5459.639 & 14.61 & 16.75  & 18.20 & 1.3m RC & ANDOR\\
2010 Oct 30 & 5499.526 & 14.78 & 16.93  & 18.55 & 2m RCC  & VA\\
2010 Oct 31 & 5500.506 & 14.85 & 17.02  & 18.70 & 2m RCC  & VA\\
2010 Nov 01 & 5501.501 & 14.81 & 16.98  & 18.64 & 2m RCC  & VA\\
2010 Nov 02 & 5502.571 & 14.86 & 17.02  & 18.67 & 2m RCC  & VA\\
2010 Nov 04 & 5505.475 & 14.78 &  $-$   &  $-$  & Schmidt & FLI\\
2010 Nov 06 & 5506.504 & 14.75 &  $-$   &  $-$  & Schmidt & FLI\\
2010 Nov 07 & 5507.514 & 14.69 & 16.76  &  $-$  & Schmidt & FLI\\
2011 Jan 01 & 5563.423 & 14.75 & 16.84  &  $-$  & Schmidt & FLI\\
2011 Jan 06 & 5568.391 & 14.75 & 16.83  & 18.37 & 2m RCC  & VA\\
2011 Jan 08 & 5570.277 & 14.76 & 16.87  & 18.48 & 2m RCC  & VA\\
2011 Jan 09 & 5571.381 & 14.79 & 16.92  & 18.52 & 2m RCC  & VA\\
2011 Feb 06 & 5599.324 & 14.58 & 16.47  &  $-$  & Schmidt & FLI\\
2011 Feb 07 & 5600.302 & 14.59 & 16.56  &  $-$  & Schmidt & FLI\\
2011 Apr 04 & 5656.256 & 14.72 & 16.74  &  $-$  & Schmidt & FLI\\
2011 Apr 09 & 5661.263 & 14.65 & 16.71  & 18.41 & 2m RCC  & VA\\
2011 Sep 11 & 5815.567 & 14.89 & 17.06  & 18.65 & 1.3m RC & ANDOR\\
2011 Sep 12 & 5816.594 & 14.92 & 17.13  & 18.64 & 1.3m RC & ANDOR\\
2011 Sep 20 & 5824.540 & 14.94 & 17.14  & 18.65 & 1.3m RC & ANDOR\\
2011 Oct 08 & 5842.513 & 14.77 & 16.87  & 18.31 & 1.3m RC & ANDOR\\
2011 Oct 14 & 5848.502 & 14.93 & 17.06  & 18.65 & 1.3m RC & ANDOR\\
2011 Oct 30 & 5865.486 & 14.82 & 16.99  & 18.76 & 2m RCC  & VA\\
2011 Nov 01 & 5866.530 & 14.73 & 16.92  & 18.56 & 2m RCC  & VA\\
2011 Nov 26 & 5892.477 & 14.99 & 17.05  & 18.66 & 2m RCC  & VA\\
2011 Nov 27 & 5893.420 & 14.85 & 16.88  &  $-$  & Schmidt & FLI\\
2011 Nov 29 & 5895.489 & 14.84 & 16.87  &  $-$  & Schmidt & FLI\\
2011 Nov 30 & 5896.445 & 14.90 & 16.92  &  $-$  & Schmidt & FLI\\
2011 Dec 29 & 5925.475 & 14.85 & 16.82  &  $-$  & Schmidt & FLI\\
2012 Jan 01 & 5928.383 & 14.81 & 16.78  &  $-$  & Schmidt & FLI\\
2012 Mar 16 & 6003.261 & 14.72 & 16.73  &  $-$  & Schmidt & FLI\\
2012 Mar 26 & 6013.262 & 14.89 & 16.95  & 18.49 & 2m RCC  & VA\\
2012 Mar 28 & 6015.312 & 14.83 & 16.88  &  $-$  & 2m RCC  & VA\\
2012 Apr 12 & 6030.270 & 14.88 & 16.85  &  $-$  & Schmidt & FLI\\
\noalign{\smallskip}
\hline
\end{tabular}
\end{center}
}
\end{table}

\IBVSfig{10cm}{6025-f1.eps}{$V$, $R_{\mathrm C}$ and $I_{\mathrm C}$ light curves of V1647~Ori}
\IBVSfigKey{6025-f1.eps}{V1647 Ori}{light curve}

The long-term photometric study of V1647 Ori can be very useful to determine the type of the eruption: FUor or EXor.
Our observations suggest that the second outburst of V1647 Ori persists for approximately four years.
The photometric data show a continuous slight decrease in brightness during the period of observations.
In the meantime the star becomes redder with decreasing of its brightness.
Using a linear approximation for our data, we calculated the following values for the rates of decline: $\sim$0.07 mag yr$^{-1}$ for $I$, $\sim$0.11 mag yr$^{-1}$ for $R$ and $\sim$0.15 mag yr$^{-1}$ for $V$.
Random fluctuations in brightness with amplitudes of few tenths of magnitude and timescales of some days were recorded during the first outburst (see Aspin \& Reipurth 2009 and references therein).
Such a short time scale variability in brightness is observed during the second outburst.

According to Aspin et al. (2009) the decrease in brightness of V1647 Ori over the period 2006--2008 was caused by reduction of the accretion rate and reformation of dust in the circumstellar environment of the star.
Therefore, we observe the same outburst that has slowed down temporarily.
Such interpretation of the observational results leads Aspin et al. (2009) to the hypothesis that V1647 Ori is a FUor object.
Our data show similar photometric behavior of the star during both outbursts and also support the hypothesis of the FUor nature of V1647 Ori.
On the other hand the spectrum of the star during the second outburst remains similar to the spectra of EXor objects (Aspin 2011). 
Therefore, during the second outburst V1647 Ori continues to show the photometric properties of a FUor and the spectral properties of an EXor.


\medskip

{\it Acknowledgements:} 
This work was partly supported by grants DO 02-85 and DO 02-273 of the National Science Fund of the Ministry of Education, Youth and Science, Bulgaria.
The authors thank the Director of Skinakas Observatory Prof. I. Papamastorakis and Prof. I. Papadakis for the telescope time.
This research has made use of NASA's Astrophysics Data System.

%\newpage
\references


Acosta-Pulido, J. A., Kun, M., \'{A}brah\'{a}m, P. et al. 2007, {\it AJ}, {\bf 133}, 2020

Aspin, C. 2011, {\it AJ}, {\bf 142}, 135

Aspin, C., Beck, T. L., Reipurth, B. 2008, {\it AJ}, {\bf 135}, 423

Aspin, C., Reipurth, B., Beck, T. L. et al. 2009, {\it ApJ}, {\bf 692}, L67

Aspin, C., Reipurth, B. 2009, {\it AJ}, {\bf 138}, 1137

Brice\~{n}o, C., Vivas, A. K., Hernandez, J. et al. 2004, {\it ApJ}, {\bf 606}, L123

Fedele, D., van den Ancker, M. E., Petr-Gotzens, M. G., et al. 2007, {\it A\&A}, {\bf 472}, 207

Garc\'ia-Alvarez, D., Wright, N. J., Drake, J. J. et al. 2011, {\it ASP Conference Series}, {\bf 448}, 609 (arXiv:1108.0828)

Herbig, G. H. 2008, {\it AJ}, {\bf 135}, 637

Itagaki, K., Nakano, S., Yamaoka, H. 2008, {\it IAUC}, {\bf 8968}

Kaurav, S. S., Ojha, D. K., Ninan, J. P., et al. 2010, {\it ASI Conference Series}, {\bf 1}, 237

K\'osp\'al, A., \'{A}brah\'{a}m, P., Acosta-Pulido, J., et al.
 2005, {\it IBVS}, 5661

Kun, M. 2008, {\it IBVS}, {\bf 5850}

McNeil, J. W. 2004, {\it IAU Circ.}, {\bf 8284}

Semkov, E. H. 2004, {\it IBVS}, {\bf 5578}

Semkov, E. H., 2006, {\it IBVS}, {\bf 5683}

Teets, W. K., Weintraub, D. A., Grosso, N., et al. 2011, {\it ApJ}, {\bf 741}, 83


\endreferences


\IBVSedata{6025-t2.txt}
\IBVSdataKey{6025-t2.txt}{V1647 Ori}{photometry}

\end{document}
