Recent research under NASA grant NAG5-971 consisted of the performance of two projects in conjunction with the International Ultraviolet Explorer (IUE) satellites. These are: (1) to look at the ultraviolet spectra of subluminous stars identified from visual wavelength spectroscopy that had been originally discovered from the Kiso Schmidt survey for ultraviolet excess stars and (2) to carry out a systematic reanalysis of the archived IUE spectra of white dwarfs. This report presents information on the progress of the re-reduction of over 600 IUE white dwarf spectra and their subsequent analysis employing model atmospheres and the observation of the Kiso ultraviolet excess stars

Wegner, Gary A.

English

NASA Technical Reports Server

Semi-Annual Report
'For NASA Grant NAG5-971
National Aeronautics and Space Admnistration
IUE Guest Observer Program
Goddard 'Space Flight Center
Greenbelt, MD 20771
^ Ultraviolet Spectra of Subluminous Objects Found
o in the Kiso Schmidt Survey
u> (J) r-
<N jxj o and
«o u st
1& § o • Systematic Reanalysis of the
Archived Ultraviolet Spectra of White Dwarfs Observed
cr> with the IUE Satellite under the
^ Astrophysics Data Program (ADP)
£3
o e>
ft* w H => Submitted by: Gary A. Wegner
° |Jj 3
 w Associate Professor
w^S3^ S-S; * 
e* H «c *< _j Department of Physics
^ ** ^  ° £j and Astronomy
SjSwS'* Phone: 603/646-3329
iH c-i Oi
en vj CJ
•-J 1-1 H Ai » '
M « S3 • ' M Trustees of Dartmouth College
•tq o si ti| aj PO Box 7
Hulwo*"1 Hanover, NH 03755
M VI M 05 •j =3 to ^  p. H
.^£j ^  P5 * Duration: One Year
I'-O T H Q
l ^ o S ^ S September 1, 1987 to August 31, 1988
l CN b> Q O3
co to ca Pt» CM
.«~ P =3 s» cn
it O t/1 H iii
' « » 33 O
i U M H O
; I ail Q P3 V)
' "3 t-^ a tq
i* f) ¥ "* '* "GarY A-I w» jj ri ^ Principal Investigator
Date ^^ L£, lO I
https://ntrs.nasa.gov/search.jsp?R=19880016022 2020-03-20T06:42:04+00:00Z
-1-
ABSTRACT
Recent research work connected with Grant NAG5-971 from the
National Aeronautics and Space Administration has been to carry out
two projects in conjunction with the International Ultraviolet
Explorer (IUE) satellite. These are: (1) to look at the ultraviolet
spectra of subluminous stars identified from visual wavelength
spectroscopy that had been originally discovered from the Kiso
Schmidt survey for ultraviolet excess stars and (2) to carry out a
systematic reanalysis of the archived IUE spectra of white dwarfs.
This report presents information on the progress on the
re-reduction of over 600 IUE white dwarf spectra and their
subsequent analysis employing model atmospheres and the observation
of the Kiso ultraviolet excess stars.
INTRODUCTION
The purpose of the research with the International Ultraviolet
Explorer (IUE) being reported here has been in two parts. The first
project to be described was the observation of the ultraviolet
spectra of hot subluminous stars that were originally found in the
Kiso Schmidt ultraviolet excess survey by Noguchi, Maehara, and
Kondo (1980) and Kondo, Noguchi, and Maehara (1984) which have been
observed spectroscopically from the ground in a continuing study
described in the papers by Wegner and McMahan (1987) and Wegner et
al (1987a,b).
II. OBSERVATIONAL RESULTS
The recently proposed observations of the more interesting
bright stars of the above Kiso sample were carried out successfully
in February of 1988 under the auspices of NASA Grant NAG5-971 and
are summarized in Table I.
-2-
Table I
Images of Kiso Objects Obtained under the
Auspices of Grant NAG5-971
Object Date (1988)
LWP
LWP
LWP
LWP
LWP
LWP
LWP
LWP
LWP
SWP
SWP
SWP
SWP
SWP
SWP
SWP
12675
12676
12682
12683
12684
12688
12689
12690
12691
32932
32933
32935
32936
32937
32939
32940
KUV18284+6650
KUV03036-0043
KUV13106+3157
WD1104+602
KUV02503-0238
KUV15537+2006
WD1615-154
KUV08599+4130
WD1406+590
KUV18284+6650
KUV03036-0043
KUV15537+2006
WD1104+602 (G197-4)
KUV02503-0238
KUV13106+3157
KUV08599+4130
February 16
February 16
February 17
February 17
February 17
February 18
February 18
February 18
February 18
February 16
February 16
February 17
February 17
February 17
February 18
February 18
-3-
III. REANALYSIS OF ARCHIVED WHITE DWARF SPECTRA
In the last year, the re-reduction of archived IUE white dwarf
spectra has progressed well and this phase of the research is
nearly completed. Much of this work has been done by graduate
student, Steven R. Swanson who has been supported by this grant.
Initially, two trips were made to Goddard Space Flight Center to
learn the use of the RDAF facility and to begin the archive
reductions. More recently, all work had been done remotely from
Dartmouth using the RDAF through the SPAN network.
In 1987, we counted 666 low resolution SWP, LWR, and LWP white
dwarf spectra available in the IUE archives, but this number has
continued to rise and currently is over 750. The plan for
re-reduction of the white dwarf spectra with the RDAF has been as
follows:
(1) All available photo-writes were inspected to assess the
image quality. Lower quality spectra were re-reduced using the GEX
Gaussian extraction routines.'
(2) Well exposed images were reduced using SWPFIX. All SWP
images obtaine'd prior to 1981 had to be rerun using this routine to
correct for the earlier faulty flux calibration.
(3) The underexposed images were reduced using BSPOT to take
out reseau artifacts. The well exposed images were corrected for
this using PATCH.
(4) LWP spectra were corrected for camera degradation and
consequently all LWP spectra are being re-reduced from the raw
data.
(5) After completing the above steps, all spectra of a given
star are rebinned and summed to obtain composites for each
wavelength region and then merged.
(6) The 'merged data will then be rebinned to 50 A bins and
will cover a wavelength interval of 1200 - 3200 A.
The ultimate goal of this phase of the research is to publish
a catalog of the ultraviolet spectra of this binned data for the
white dwarfs.
-4
-
T
2
in
 m
vl
03 tr>C•H10
 W
 EM
3
 D
 rtj-
H
 q
Ti
 
S
0)x;
 Q)
|
 
t
 
f
M
T3
 
-P
0
 C
}-(
 
-H
 
tjl
p)
 
£
in
 
-H
oo
 
c
 
w
.
 m
 o
 3
1
 
-H
o
 
-P
 c
<N
 U
 O
.O
 
3
 
-H
M-l
 
<U
 O
I
 I
 
1
 I
 
2
13
0)^i
d>
 
-H
-P
 
tn
 
^
•H
 
-H
5
 
0
3O
a)
 
a)
A
 x:
 
-a
4-1
 M
 
cm
o
 
•
 
-P
w
 m
<
*
 s
 <D
in
 
(d
 rH
r-H
 
t^
 
0
>
 
-P
ft
 
o
 x:
 x:
;s
 
^
 
.p
 in
c
 n
a)
 C
 o
tr>
 o
 
<1)
to
 
-H
 c
 
x;
-H
 o
 
o
3
 x
:
 c
m
 T)
 in
 o
O
 
a)s-j
 
w
 
to
C
 
-H
 
-H
O
 
-P
•H
 
0)
 
0)
 
<U
tt
 
t
 I
 
^
 
f
^
It)
 
Q)
 
-H
 
-H
CUM-I
 
.n
 
-p
6
^
0
3
.
 o
 
-H
 ^
 o
O
 T3
 (0
 M
Io
•
 HEn
CM;
 
o
-
o
 
-H
TD
 in
 Q
<
C
 
>i
•
 n3
 o
 
JJ
^J
13
 
fl
<D
 
v
O
 (1)
 w
 
•
3
 
C
 
-P
 C
C
 
C
 O
Q)
 
-H
I
 
Q)
<1>
 
V)nJ
U-l
 
Vt
 
>
O
 
-PO
 
C
(1)
 (D
 
-r Q)W
 
-P
<U
 
O3
W
0)I0)0)
X
 
<D
 
•
 W
'O
 
O
ft
 CO
 
-H
H
 C
 C
C
 
<1)
 
-H
 
-rt
\c^rm
 v
Z
 
Z
^
 
«
 
m
 v
fo
 vu
~
»
^LJ
t
-
I|LJ
-5-
Examples of the effect of the improved data reductions are
shown in Figure 1. The first spectral scan shows the results for
the originally extracted spectra as they exist in the IUE archives,
and the second is the re-reduced spectrum of the object and the
same original data, but utilizing the new RDAF reduction programs.
Finally, the third graph indicates the appearance of a typical
finished re-reduction.
III. MODEL ATMOSPHERES
It is also planned to obtain the atmospheric parameters for
the white dwarfs using fits to model atmospheres. The following
progress has been made towards achieving this goal. This is being
done using the atmosphere code LUCIFER, originally developed by E.
P. Nelan and described to some extent in Nelan and Wegner (1985).
Some of this work is being done in collaboration with Nelan, but
this program is also running at Dartmouth on a micro-Vax computer.
Figure 2 shows some of the emergent fluxes for a selection of pure
hydrogen DA model atmospheres at a fixed gravity of logg=7.6 and
covering a range of effective temperature. Of particular interest
for the IUE research is the behavior of the quasi-molecular
absorptions in the ultraviolet.
IV. CONCLUSIONS
Since the last semi-annual report, work has been conducted on
white dwarfs and other subluminous stars. The basic results of
these investigations can be summarized briefly as follows:
(1) The ultraviolet spectra of additional hot subluminous
stars in the' Kiso Schmidt ultraviolet excess survey have been
observed.
(2) The re-reduction of about 350 white dwarf spectra in the
IUE archives is nearly completed and progress has been made on the
determination of their atmospheric parameters using model
atmospheres.
-6-
8
FIG. 2 - Examples of some of the pure hydrogen DA white
dwarf atmospheres to be used with the IUE data.
For these, log g =7.6 and effective temperatures
run from 8000 *K (top) to 21000°K (bottom).
-7-
REFERENCES
Kondo, M., Noguchi, T., and Maehara, H., 1984, Ann. Tokyo Astron.
Obs., 20, 130.
Nelan, E, P. and Wegner, G. 1985, Astrophys. J. (Letters),
289, L31.
Noguchi, T., Maehara, H., and Kondo, M., 1980, Ann. Tokyo Astron.
Obs., 20, 130.
Wegner, G. and McMahan, R. K., 1985, Astron. J., 90, 1511.
Wegner, G. and McMahan, R. K., 1986, Astron. J., 91, 139.
Wegner, G. and McMahan, R. K., and Boley, F. I., 1987, Astron. J.,
94, 1271.
Wegner, G., Boley, F. I., Swanson, S. R., and McMahan, R. K. 1987,
in IAU Coll. No. 95, The Second Conference on Faint Blue
Stars, A. G. D. Philip, D. S. Hayes, and J. W. Liebert, eds.,
(Schenectady: L. Davis Press), p. 501.
APPENDIX I
The attached reprints of papers contain material obtained with
the IUE either from this grant or the earlier one, NAG5-287.
A. "Ultraviolet and Visual Spectroscopy of DB White Dwarfs," by
G. Wegner and E. P. Nelan,1987, Astrophys. J., 319, 916-929.
B. "Spectroscopic Surveys of Faint Blue Stars," by G. Wegner, F.
I. Boley, S. R. Swanson, and R. K. McMahan,1987, in
Proceedings IAU Colloquium No.95,The Second Conference on
Faint Blue Stars, A. G. D. Philip, D. S. Hayes, and J. W.
Liebert, eds., (Schenectady: L. Davis Press),501-504.


Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey and Systematic Reanalysis of the Archived Ultraviolet Spectra of White Dwarfs Observed with the IUE Satellite Under the Astrophysics Data Program (ADP)

Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey and Systematic Reanalysis of the Archived Ultraviolet Spectra of White Dwarfs Observed with the IUE Satellite Under the Astrophysics Data Program (ADP)

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server