Transcript The dwarf nova BZ UMa

The dwarf nova BZ UMa
Simultaneous photometry and echellespectroscopy during the 2005 January Outburst
MNRAS, 2006, Coming Soon
Vitaly Neustroev (NUI Galway), S. Zharikov and R. Michel
BZ UMa





Period: 97.8 min
Outburst cycle: > 300d
Min: V≈16-17 (17.8)
Max: V≈10.5-11.5
Very strong Balmer emission lines
Relative Intencity
Spectrum
6
3
0
Inst.
4000
4200
4400
4600
4800
5000
Wavelength
H
H
3940
3960
3980
4080
H
H
4100
4120
4320
4340
4360
4840
4860
4880
Doppler Tomography

April, 2004. Quiescence: Hα
Observations



OAN SPM (Mexico)
Photometry: 2005 Jan 12-13 and 15-17
Echelle-spectroscopy: 2005 Jan 15-17
Light Curve
11
12
Magnitude (V)
13
14
15
16
17
3383
3384
3385
3386
3387
3388
HJD (2450000+)
3389
3390
3391
3392
Light Curve
11
12
Magnitude (V)
13
14
15
16
17
3383
3384
3385
3386
3387
3388
HJD (2450000+)
3389
3390
3391
3392
Light Curve
11
Our observations
AAVSO
12
Magnitude (V)
13
14
15
16
17
3383
3384
3385
3386
3387
3388
HJD (2450000+)
3389
3390
3391
3392
Light Curve
11
12
Magnitude (V)
13
14
15
16
17
3386.70
3386.75
3386.80
3386.85
3386.90
3386.95
HJD (2450000+)
3387.00
3387.05
3387.10
Colours
11
0.0
12
-0.2
-0.4
14
-0.6
Dec 2004
Magnitude
13
15
u'-b'
b'-v'
v'-r'
V (right Y)
-0.8
-1.0
16
17
385.5
386.0
386.5
387.0
HJD (2453000+)
387.5
388.0
Line profiles
Relative intensity
3.5
HeI 4713
H
NIII 4637
CIII 4658
4.0
HeII 4686
4.5
HeI 5876
H
H
3.0
Jan 15
2.5
Jan 16, 1 stage
st
x 10
nd
2.0
Jan 16, 2 stage
1.5
Jan 16, 3 Stage
1.0
Jan 17
4300
rd
4350
4600
4650
4700
4750
4850
Wavelength
4900
5850 5900
6550 6600
FWHM, Fluxes and EW of Hα
3
80
30
2
1
20
EW
100
Dec 2004
200
10
0
0
85.8 86.0 86.2
86.8 87.0
HJD (+2453300)
87.8 88.0 88.2
V flux (mJy)
15
H flux
90
20
Dec 2004
FWHM
25
Doppler Tomography

April, 2004. Quiescence: Hα
Doppler Tomography

Jan 15, 2005. Preoutburst: Hα
Doppler Tomography

Jan 16, 2005. Outburst, 1st stage: Hα
Doppler Tomography

Jan 16, 2005. Outburst, 3rd stage: Hα
Doppler Tomography

Jan 17, 2005. Outburst, Decline: Hα
Doppler Tomography

Jan 17, 2005. Outburst, Decline: Hβ
Doppler Tomography

Jan 17, 2005. Outburst, Decline: He I 5876
Inside-Out or Outside-In outburst?


The only way to be sure of the outburst type is
from eclipse profile observations during
outbursts and BZ UMa is not an eclipsed
system.
A very low mass-transfer rate for BZ UMa
(≤1015 g/s) implies that theoretically, its
outbursts should be of an inside-out type.
Line profiles
Relative intensity
3.5
HeI 4713
H
NIII 4637
CIII 4658
4.0
HeII 4686
4.5
HeI 5876
H
H
3.0
Jan 15
2.5
Jan 16, 1 stage
st
x 10
nd
2.0
Jan 16, 2 stage
1.5
Jan 16, 3 Stage
1.0
Jan 17
4300
rd
4350
4600
4650
4700
4750
4850
Wavelength
4900
5850 5900
6550 6600
Line profiles
4.5
4.0
H
H
Relative intensity
3.5
3.0
Jan 15
2.5
Jan 16, 1 stage
2.0
Jan 16, 2 stage
1.5
Jan 16, 3 Stage
1.0
Jan 17
4300
st
nd
rd
4350
4850
Wavelength
4900
Line profiles
4.5
4.0
H
H
Relative intensity
3.5
3.0
Jan 15
2.5
Jan 16, 1 stage
2.0
Jan 16, 2 stage
1.5
Jan 16, 3 Stage
1.0
Jan 17
4300
st
nd
rd
4350
4850
Wavelength
4900
Summary




We reported simultaneous photometric and echellespectroscopic observations of the dwarf nova BZ UMa during
which we were lucky to catch the system at the onset of an
outburst.
Using Doppler tomography we found that the unusual emission
distribution detected in quiescence held during the outburst.
On the base of the spectral changes during the rising stage we
conclude that the 2005 January outburst of BZ UMa was of the
inside-out type.
Nevertheless, a highly asymmetrical light curve with a “jump”
shows that this outburst cannot easily be fit into the framework
of the current Disc Instability Model.