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GTC and WHT observations of ultracompactAMCVn binaries
Thomas Kupfer
Radboud University Nijmegen
Co-Is: Paul Groot, Gijs Nelemans (RU), David Levitan, Tom Prince (Caltech)
Danny Steeghs (Warwick), Rene Rutten (Grantecan)
SDSS J1208+3550 - Porb=52.57min
SDSS J1642+1934 - Porb=54.12min
SDSS J1525+3600 - Porb=44.17min
SDSS J0129+3842 - Porb=37.33min
SDSS J1908+3940 - AM CVn or no AM CVn??
SDSS J1208+3550 observed with the WHT
3500 4000 4500 5000 5500 6000 6500 7000 7500 8000
5×10
−17
10−1
61.
5×10
−16
2×10
−16
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
HeI
728
1
HeI
706
5
HeI
667
8
HeI
587
5
HeI
501
5
Dic
hroi
c
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
402
6H
eI 3
964
HeI
388
8
HeI
381
9
HeI
370
5
HeI
I 468
5
3800 3850 3900 3950
5×10
−1710
−16 1.
5×10
−16
2×10
−16
MgI
383
2M
gI 3
838
SiII
385
3/56
SiII
386
2
SiI
3905
5840 5860 5880 5900
10−1
61.
5×10
−16
I Typical emission lines for long period system with strongcentral spike
I Strong absorption features in the blue side of the spectrum
Spectroscopic period of SDSS J1208+3550
21.81.61.41.21
0.80.60.40.20
10005000-500-1000
1000
500
0
-500
-1000
10005000-500-1000 10005000-500-1000 10005000-500-1000 10005000-500-1000 10005000-500-1000
Hei λ3888
Phase
Hei λ4471 Heii λ4685 Hei λ5875 Hei λ6678 Hei λ7065
X-Velocity [kms−1]
Y-V
elocity
[kms−
1]
X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1]
I Kinematics analysis gives period of 52.57 min
I Trailed spectra revealed second bright spot
I ∼120◦ offset very similar to SDSS J1240
I Origin unclear
Absorption in SDSS J1208+3550
3600 3800 4000 4200
10−1
61.
5×10
−16
2×10
−16
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
HeI
3705
MgI
3832
/38
SiII
3853
/56/
62
SiI
3905
-60
-40
-20
0
20
40
60
80
100
0 2 4 6 8 10 12
Vel
[km
/s]
Phasebin
I No periodic velocity shifts detected⇒ Originates most likely in the extended photosphere of theaccretor
I System much older than settling times of white dwarf⇒ Has to be accreted material
Absorption in SDSS J1208+3550
3600 3800 4000 4200
10−1
61.
5×10
−16
2×10
−16
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
HeI
3705
MgI
3832
/38
SiII
3853
/56/
62
SiI
3905
-60
-40
-20
0
20
40
60
80
100
0 2 4 6 8 10 12
Vel
[km
/s]
Phasebin
I Absorption lines known from accreting DBZ white dwarfs⇒ BUT In DBZ white dwarfs Mg always shows up with Ca
I SDSS J1208 shows very strong Mg but no Ca
I Is it the only system with strange abundance ratio??
SDSS J1642+1934 observed with the GTC
4000 4500 5000 5500 6000 6500 7000 7500
2×10
−17
4×10
−17
6×10
−17
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
atm
os.
atm
os.
atm
os.
atm
os.
HeI
728
1
HeI
706
5
HeI
667
8
HeI
587
5
HeI
501
5
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
402
6
HeI
I 468
5
MgI
b
6660 6670 6680 6690
2×10
−17
3×10
−17
I Very strong and narrow emission lines
I Narrow double peaked profiles from the disc
Kinematics of SDSS J1642+1934
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
10005000-500-1000
1000
500
0
-500
-1000
10005000-500-1000 10005000-500-1000
Hei λ5875
Phase
Hei λ6678 Hei λ7065
X-Velocity [kms−1]
Y-V
elocity[kms−
1]
X-Velocity [kms−1] X-Velocity [kms−1]
Combined helium lines
5000-500
21.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.20
Velocity [kms−1]
Phase
I Very weak bright spot, only trail with combined lines revealedbright spot
I Porb=54.12min ⇒ Third longest known orbital period
I Dimming of bright spot, also seen in AM CVn and SDSS J0804
I Fairly low velocity amplitude <400 kms−1
Metal lines in SDSS J1642+1934
3500 4000 4500 5000−10−1
70
10−1
72×
10−1
73×
10−1
74×
10−1
7
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
5015
HeI
4921
HeI
4713
HeI
4471
HeI
4388
HeI
4026
HeI
3888
HeI
I468
5
MgI
3832
/38
I GTC does not go that far blue⇒ Identification spectrum with Palomar 200” telescope
I Like SDSS J1208, strong Mg absorption but no Ca
SDSS J1208, SDSS J1642 and SDSS J1552
3500 4000 4500 5000−10−1
70
10−1
72×
10−1
73×
10−1
74×
10−1
7
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
5015
HeI
4921
HeI
4713
HeI
4471
HeI
4388
HeI
4026
HeI
3888
HeI
I468
5
MgI
3832
/38
SDSS J1642+1934
3600 3800 4000 4200
10−1
61.
5×10
−16
2×10
−16
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
HeI
3705
MgI
3832
/38
SiII
3853
/56/
62
SiI
3905
SDSS J1208+3550
3800 4000 4200
3×10
−17
5×10
−17
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
MgI
3832
/38
SDSS J1552+3201
I All three systems show Mg but no CaI Lines in all spectra not resolved
SDSS J1208, SDSS J1642 and SDSS J1552
3500 4000 4500 5000−10−1
70
10−1
72×
10−1
73×
10−1
74×
10−1
7
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
5015
HeI
4921
HeI
4713
HeI
4471
HeI
4388
HeI
4026
HeI
3888
HeI
I468
5
MgI
3832
/38
SDSS J1642+1934
3600 3800 4000 4200
10−1
61.
5×10
−16
2×10
−16
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
HeI
3705
MgI
3832
/38
SiII
3853
/56/
62
SiI
3905
SDSS J1208+3550
3800 4000 4200
3×10
−17
5×10
−17
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
HeI
4026
HeI
3964
HeI
3888
HeI
3819
MgI
3832
/38
SDSS J1552+3201
I Where exactly do these lines originate??I How can we explain absence of Ca but strong Mg??
SDSS J1525+3600 observed with the GTC
4000 4500 5000 5500 6000 6500 7000 7500
10−1
72×
10−1
73×
10−1
74×
10−1
75×
10−1
7
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
atm
os.
atm
os.
atm
os.
atm
os.
HeI
728
1
HeI
706
5
HeI
667
8
HeI
587
5
HeI
501
5
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
402
6
HeI
I 468
5
I Strong emission features from the disc and absorption linesfrom accreting white dwarf⇒ Temperature of white dwarf still high (∼ 20 000 K)⇒ Expected Porb < 40 min
Kinematics of SDSS J1525+3600
21.81.61.41.21
0.80.60.40.20
10005000-500-1000
1000
500
0
-500
-1000
10005000-500-1000 10005000-500-1000 10005000-500-1000
Hei λ5015
Phase
Hei λ5875 Hei λ6675 Hei λ7065
X-Velocity [kms−1]
Y-V
elocity
[kms−
1]
X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1]
I Kinematic analysis gives an orbital period of 44.17 min
I System is as an AM CVn already several billion years old(Bildsten et al. (2006))
⇒ What keeps accreting white dwarf so hot??
SDSS J0129+3842 observed with the GTC
4000 4500 5000 5500 6000 6500 7000 7500
10−1
72×
10−1
73×
10−1
7
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
atm
os.
atm
os.
atm
os.
atm
os.
HeI
728
1
HeI
706
5
HeI
667
8
HeI
587
5
HeI
501
5
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
402
6
HeI
I 468
5
Fe
II
SiII
633
8S
iII 6
381
I Beside helium, emission of Iron and Silicon from the disc
I Weak absorption lines from accreting white dwarf
Kinematics of SDSS J0129+3842
21.81.61.41.21
0.80.60.40.20
10005000-500-1000
1000
500
0
-500
-1000
10005000-500-1000 10005000-500-1000 10005000-500-1000 10005000-500-1000 10005000-500-1000
Hei λ4471
Phase
Heii λ4685 Hei λ5015 Hei λ5875 Hei λ6678 Hei λ7065
X-Velocity [kms−1]
Y-V
elocity
[kms−
1]
X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1] X-Velocity [kms−1]
I Kinematics analysis gives period of 37.33 min
I Shears et al. (2011) obtained a superhump period of 37.9 min⇒ Results in period excess ε=0.015⇒ With equation from Patterson et al. (2005) mass ratioq=0.074
Bringing all together
I Periods of four systems confirmed
I SDSSJ1208 shows second bright spot
I All three systems between 50 – 60 min period show strangeline ratios between Magnesium and Calcium
I SDSSJ1525 is first system showing the accretor and has aperiod well above 40min
Upcoming runs
I 16 hours in total on the GTC forSDSS J1427-0123, SDSS J1721+2733 and SDSS J1730+5545
I 3 nights on the WHT on SDSSJ1730+5545
SDSS J1908+3940
I AM CVn candidate found by the Kepler satellite
I Two photometric periods detected in the Kepler data(Psh=15.89min and Porb=15.64min)
I Strong helium absorption lines typical for a high state system
I Spectrum could not be modelled with normal DB models(Fontaine et al. (2011))
BUTFollow up observations to proof the AM CVn nature necessary
SDSS J1908+3940 observed with the WHT
4300 4400 4500 4600 4700 4800 4900 5000 51006×10
−16
8×10
−16
10−1
51.
2×10
−15
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
HeI
501
5
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
443
7
HeI
504
7
I Phase resolved spectroscopy with the WHT over 5 nights⇒ Resulting in 1876 spectra with SNR=1-4 per spectrum
I Average spectrum shows He absorption and weak metal lines
SDSS J1908+3940 observed with the GTC
3900 4000 4100 4200 4300 4400 4500 4600 4700 4800 4900 5000 5100 5200
10−1
71.
5×10
−17
2×10
−17
2.5×
10−1
73×
10−1
73.
5×10
−17
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
HeI
501
5
HeI
492
1
HeI
471
3
HeI
447
1
HeI
438
8
HeI
402
6
HeI
396
4
HeI
402
3
HeI
412
0H
eI 4
143
HeI
416
9
HeI
443
7
HeI
504
7
I Phase resolved spectroscopy with the GTC over 3 nights⇒ Resulting in 222 spectra
I Lower resolution but greater wavelength coverage than inWHT data
I Average spectrum (SNR∼200) shows even more weak metallines
Weak metal lines in SDSS J1908+3940 from WHT data
4500 4550 4600 4650 4700
9.5
×10
−1
610
−1
51.0
5×
10
−1
5
λ[Å]
Fλ[
erg
cm−
2s−
1Å
−1]
?? NII
NIIN
IIN
IIN
IIN
IIN
IISi II
ISi II
ISi II
I
4600 4610 4620 4630 4640
9.5×
10−1
610
−15
λ[Å]
F λ[e
rgcm
−2s−1
Å−1
]
NII
NII
NII
NII
NII
I Weak metal lines ofNii, Siii/iii and Mgii
I Lines well resolved
I FHWM of nitrogen lines∼ 200 kms−1
Weak metal lines in SDSS J1908+3940 from GTC data
4150 4200 4250 4300
2.8×
10−1
72.
9×10
−17
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
He I
Si II N II C II?
4500 4550 4600 4650 4700
2.3×
10−1
72.
4×10
−17
2.5×
10−1
7
λ[Å]
Fλ[e
rg c
m−2
s−1
Å−1
]
?? N II N IIN IIN IIN II N II N IISi III
Si IIISi II
I
I Large sample of metal lines from different species⇒ Nii, Siii/iii, Mgii and possibly Cii and Oii
Kinematics in SDSS J1908+3940
Folded on P=15.64min
150010005000-500-1000-1500-2000
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
Folded on P=15.89min
150010005000-500-1000-1500-2000
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
I Every spectrum divided by the average spectrum
I Folded on the photometric periods
I No velocity variations detected
Bright spot in SDSS J1908+3940??
3002001000-100-200-300
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
3002001000-100-200-300
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
I Core of the Hei 4471 absorption line folded on thephotometric periods
I Periodic variations?? Which one is the orbital period??
Bright spot in SDSS J1908+3940??
Folded on P=15.64min
3002001000-100-200-300
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
Folded on P=15.89min
3002001000-100-200-300
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Velocity [kms−1]
Phase
I Core of the Hei 4471 absorption line folded on thephotometric periods
I Periodic variations?? Which one is the orbital period??
I 2 nights in July on Keck/ESI (R=27 000) will hopefully solvethe question
Open questions
I What can we learn from the metal lines appearing all over theplace??
I How can we explain the strange line ratios in the 50minperiod systems??
I Why is the accretor in SDSS J1525+3600 still so hot??
I What is the orbital period of SDSS J1908+3940??
