242

Acta Polytechnica CTU Proceedings 2(1): 242–245, 2015

242

doi: 10.14311/APP.2015.02.0242

Line Evolution of the Nova V5587 Sgr from Early to Nebula Phase

T. Kajikawa1, A. Arai1,2, M. Nagashima1, H. Kawakita1, M. Yamanaka3,4,5, K. Kawabata3,
S. Kiyota6

1Kyoto Sangyo University, Koyama Astronomical Observatory
2University of Hyogo, Nishi-Harima Astronomical Observatory
3Hiroshima University
4Kyoto University
5Konan University
6VSOLJ

Corresponding author: kajikawat8@gmail.com

Abstract

The spectral evolution of the nova V5587 Sgr has been monitored at Koyama Astronomical Observatory and Higashi-
Hiroshima Observatory, Japan, from the early to nebula phase. The nova rebrightened several times. The spectra during
the early phase showed emission lines of Hα, Hβ, O I, He I, He II, N II, Fe II. Nova V5587 Sgr is classified into the Fe
II type. The helium abundance of the nova is estimated as N(He)/N(H) = 0.134 ± 0.09. The light curve, the spectral
evolution, and the helium abundance in V5587 Sgr are similar to those of the nova PW Vul.

Keywords: cataclysmic variables - classical novae - optical - spectroscopy - photometry - individual: V5587 Sgr.

1 Introduction

Photometric observations of novae are usually per-
formed by many observers worldwide. The light curves
of the novae have been revealed in detail, and they can
be classified into several classes (Strope et al. 2010).
In contrast, spectroscopic observations of novae are
not performed as frequently as photometric observa-
tions because (i) the number of available spectrographs
(and observers) are limited; (ii) some fraction of no-
vae are too faint to observe by spectrographs in their
later phase (or even at the maximum for some novae).
As novae show a variety of spectral evolutions, spec-
troscopic monitoring can provide new insights into the
physics and chemistry of novae. For example, recently
Nagashima et al. (2013) detected molecular absorption
bands of C2 and CN in nova V2676 Oph. (This is the
first detection of C2 in novae and the second for CN.)
This detection was performed as a part of long-term
spectroscopic observations of this nova.

The light curves of novae in some classes (Strope
et al. 2010) can be successfully reproduced by models
(as reviewed by Prof. Kato at this meeting). However,
the light curves in the “Jitter”and “Oscillation”classes
(Strope et al. 2010) could not be reproduced well by
the models. In this paper, we focus on the “Jitter”class
and introduce our recent spectroscopic observations of
V5587 Sgr classified in this class. We discuss the nature

of this nova as it is likely that there are differrent types
of oscillations (i.e., different physical conditions) of no-
vae in the “Jitter”class. Different types of novae might

 6

 8

 10

 12

 14

 16

 18
 0  100  200  300  400  500

V
 (

m
a

g
n

itu
d

e
s)

Days after discovery (t)

V5587 Sgr
PW Vul

Figure 1: V band magnitudes of V5587 Sgr and PW
Vul. The light curve of V5587 Sgr is from Higashi-
Hiroshima Observatory, VSNET, and AAVSO observa-
tions. The light curve of PW Vul was refer to the online
data of Strope et al.(2010).

242

http://dx.doi.org/10.14311/APP.2015.02.0242


Line Evolution of the Nova V5587 Sgr from Early to Nebula Phase

be mixed together in this class. Even though there
are high-quality photometric and spectroscopic obser-
vations for some Jitter class novae, the mechanism for
their rebrightening is still unclear (Tanaka et al. 2011).
By frequent spectroscopic observations, we can observe
phenomena useful to reveal the physics of the nova. In
order to investigate the mechanism for the rebrighten-
ing in the “Jitter”class novae, we have conducted spec-
troscopic observations of V5587 Sgr in 2011 – 2012.

The nova V5587 Sgr (= Nova Sgr 2011 No.1) was
discovered on UT 2011 January 25.86 by Nishimura
(Nakano et al. 2011). The first low-dispersion spec-
trum was obtained on UT 2011 January 28 at Koyama
Astronomical Observatory. The spectrum shows promi-
nent emission lines of Hα, Hβ and O I. These features
suggest that this object is a classical nova (Arai 2011;
Imamura 2011).

2 Observations

Our photometric and spectroscopic observations were
performed at two sites. One site is Koyama Astro-
nomical Observatory (Kyoto Sangyo University, Ky-
oto, Japan). We used the 1.3m Araki telescope with
the LOSA/F2 spectrograph (Arai et al., in prep.) for
low-dispersion spectroscopy. The wavelength cover-
age is 400 – 800 nm and the spectral resolving power
is R = λ/∆λ ∼ 580 at 600 nm. The other site is
Higashi-Hiroshima Observatory (Hiroshima University,
Hiroshima, Japan). We used the 1.5m Kanata telescope
with TRISPEC (Triple Range Imager and SPECtro-
graph with polarimeter, shutdown in 2012) for photom-
etry and with HOWPol (Hiroshima One-shot Wide-field
Polarimeter) for spectroscopy. Its wavelength coverrage
is 400 – 1000 nm, and spectral resolving power is R ∼
400 at 600 nm.

 450  500  550  600  650  700  750  800  850

N
o
rm

a
liz

e
d
 f
lu

x 
+

 c
o
n
st

.

Wavelength (nm)

+596d

+229d

+213d

+185d
+167d
+154d
+147d
+129d
+100d
+93d
+81d
+69d
+68d
+61d
+60d

+45d
+43d
+39d

+35d
+27d
+11d
+9d
+8d

H
e

 I
I 

(4
6

8
.6

)

H
β

F
e

 I
I(

4
2

) 
(4

9
2

.4
)

F
e

 I
I(

4
2

) 
(5

0
1

.8
)

F
e

 I
I(

4
2

) 
(5

1
6

.9
)

[O
 I

II
] 

(4
9

5
.9

)
[O

 I
II

] 
(5

0
0

.6
)

N
 I

I 
(5

6
8

.0
)

[N
 I

I]
 (

5
7

5
.5

)

H
e

 I
 (

5
8

7
.4

)

[O
 I

] 
(6

3
0

.0
)

[O
 I

] 
(6

3
6

.3
)

H
α

H
e

 I
 (

6
6

8
.1

)

H
e

 I
 (

7
0

6
.5

)

[O
 I

I]
 (

7
3

3
.0

)

O
 I

 (
7

7
7

.4
)

Figure 2: The normalized spectra of V5587 Sgr observed from +8d (= UT 2011 February 2) to +596d (=
UT 2012 September 12) after the discovery. These spectra were obtained at Koyama Astronomical Observatory
except for the data on +35d and +45d (= UT 2001 March 3 and 12), taken at Higashi-Hiroshima Observatory.

243



T. Kajikawa et al.

3 Results

Figure 1 shows light curves of V5587 Sgr. Since V5587
Sgr showed an erratic variation in the light curve, we
consider that the nova is classified in the “Jitter”class.
Particularly, V5587 Sgr seems to be a member of the
sub-class prototyped by PW Vul as shown in Strope et
al. (2010). Based on the light curves, we determined
the date of the visual maximum as 9 days after dis-
covery and also determined t2 = 12 days and t3 = 108
days. From (B - V) at maximum magnitude and at t2,
we estimate the color excess by intersterllar extinction;
E(B - V) = 0.85 – 1.26.

The light curve of V5587 Sgr is quite similar to that
of the “Jitter”class nova PW Vul as shown Figure 1
(Schwarz et al. 1997, and references therein). PW
Vul was discovered on 1984 July 27 (= JD 2445917)
by Wakuda (Kosai 1984). This nova reached its maxi-
mum light of 6.3 magnitude in the V band on 1984 Aug
4th. We compare V5587 Sgr with PW Vul from various
viewpoints in the next section.

 500  550

N
o
rm

a
liz

e
d
 f
lu

x

Wavelength (nm)

+45d

+43d

+39d

+35d

+27d

+11d

+9d

+8d

Hβ Fe II (42)

Figure 3: The spectra of V5587 Sgr in early phase.
The nova never showed any regrowth of a P-Cygni pro-
file.

Figure 2 shows the growth of Hα, Hβ, He I, He II,
N II, [N II], O I, [O I], [O II], and Fe II emission lines of
V5587 Sgr.

Novae that exhibit rebrightening in the early phase
often show the regrowth of a P-Cygni profile (Tanaka et
al. 2011, Csak et al. 2005) as in V4745 Sgr. However,
V5587 Sgr has never shown this behavior (Figure 3).

It is considered that the nova entered into the neb-
ula phase between July 11 to July 29 because the [O
III] forbidden emission lines dominated Hβ at that time

(Figure 4). We assume that the electron density in the
nebula phase was ne = 10

6 ∼ 108 cm−3 according to
Iijima & Esenoglu (2003) and Iijima (2006), and we
estimate the helium abundance of the ejecta based on
the data between July 11 and July 29 ; N(He)/N(H) =
0.134 ± 0.09 (for ne = 106 cm−3), N(He)/N(H) = 0.139
± 0.09 (for ne = 108 cm−3).

 450  500  550  600  650  700  750  800
N

o
rm

a
liz

e
d

 f
lu

x
Wavelength (nm)

+147d

+129d

H
e
 I
I 
(4

6
8
.6

)

H
β

[O
 I
II
] 
+

 F
e
 I
I(

4
2
)

N
 I
I 
(5

6
8
.0

)

H
e
 I
 (

5
8
7
.4

)

[O
 I

] 
(6

3
0

.0
)

[O
 I

] 
(6

3
6

.3
)

H
e
 I
 (

6
6
8
.1

)

H
e
 I
 (

7
0
6
.5

)

[O
 I
I]
 (

7
3
3
.0

)

O
 I
 (

7
7
7
.4

)

Figure 4: The spectra of V5587 Sgr in nebular
phase(+129 days and +147 days after its maximum).
An emission line of He II was recognized in these spec-
tra.

4 Discussion & Conclusion

The decline rates, amplitudes, and intervals of rebright-
ening observed in V5587 Sgr are similar to those of PW
Vul. This fact suggests that the WD mass and physical
parameters related to the explosion of V5587 Sgr would
be similar to those of PW Vul. Comparison between the
spectra of V5587 Sgr and PW Vul also lead us to the
same conclusion, namely, they are similar to each other,
e.g., the late-phase spectra of V5587 Sgr (shown in Fig-
ure 4 in Rosino and Iijima 1987). Figure 5 also shows
helium abundances vs t3 in 20 various novae. Helium
abundance of V5587 Sgr seems to be similar to that of
PW Vul. This figure indicates that helium abundance
is not correlated with t3.

In summary, we have performed photometric and
low-dispersion spectroscopic observations of V5587 Sgr
from early to nebula phase. The photometry showed
erratic variations of the light curve. The spectra dur-
ing the early phase showed emission lines of Hα, Hβ,
and Fe II (i.e., Fe II type) and V5587 Sgr never showed
regrowth of a P-Cygni profile. The nova entered the
nebula phase between July 11 to July 29 (t = 158 to
178days). We estimated that the helium abundance of
V5587 Sgr is N(He)/N(H) = 0.134 ± 0.09. The nova is
very similar to PW Vul considering decline rates, spec-
tral features, and helium abundance. We obtained a
new sample of the “Jitter”class novae.

244



Line Evolution of the Nova V5587 Sgr from Early to Nebula Phase

-1

-0.5

 0

 0.5

 0.5  1  1.5  2  2.5  3  3.5

lo
g

1
0
(N

(H
e
)/

N
(H

))

log10t3

V1494 Aql(1)

V723 Cas(2)

V2468 Cyg(3)

Cl Aql(4)

V407 Cyg(5)

V1500 Cyg(6)

QU Vul(7)

V351 Pup(8)

U Sco(9)

PW Vul(10),(11)

V842 Cen(11)

V827 Her(11)

QV Vul(11)

V2214 Oph(11)

V977 Sco(11)

V443 Sct(11)

V1668 Cyg(11)

V693 CrA(11)

V1370 Aql(11)

V5587 Sgr

Figure 5: The helium abundance of 20 novae. References: (1) Iijima & Esenoglu (2003); (2) Iijima (2006); (3)
Iijima & Naito (2011); (4) Iijima (2012a); (5) Iijima (2012b); (6) Ferland (1978); (7) Schwarz (2002); (8) Saizar
(1996); (9) Iijima (2002); (10) Schwarz et al. (1997); (11) Andreä et al. (1994).

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http://dx.doi.org/10.1086/155818
http://dx.doi.org/10.1007/BF00654989
http://dx.doi.org/10.1086/169630
http://dx.doi.org/10.1093/mnras/279.1.280
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	Introduction
	Observations
	Results
	Discussion & Conclusion