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ELECTRONIC NEWSLETTER OF THE EUVE OBSERVATORY
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Vol 6, No. 2 29 Feb 1996 ISSN 1065-3597
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(C) 1996, Regents of the University of California
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Notes from the Editor
=====================
by Brett A. Stroozas, ISO Manager
Welcome to the electronic newsletter for NASA's Extreme Ultraviolet
Explorer (EUVE) satellite, compiled and published monthly by the
Integrated/Intelligent Science Operations (ISO) group at the Center for
EUV Astrophysics (CEA) at the University of California, Berkeley (UCB).
The contents of this issue of the EUVE electronic newsletter are as
follows:
1. Science News
1.1 Recent EUVE Science Highlights
1.2 Abstracts of Recently *Accepted* EUVE Papers
2. Science Operations News
2.1 Hot Spots in the SW Spectrometer
2.2 Public Data Release for 1 Mar 1996
2.3 On-Line Access to EUVE
3. CEA Job Listings
To comment on or make suggestions for the EUVE electronic newsletter,
please send e-mail to ceanews@cea.berkeley.edu (Internet).
The EUVE observatory performed well throughout the month of Jan
1996, conducting observations of the following Guest Observer (GO)
targets (alternate name and spectral type information taken from the
SIMBAD or internal CEA databases; "NOIDs" are unidentified objects):
===================================================================
Target Alternate Spectral Observation
Name Name Type GMT Date(s) Notes
===================================================================
GJ 354.1 HD 82443 K0 31 Dec - 11 Jan 1996 ---
NGC 5457 M 101 Glxy 11 Jan - 11 Jan 1996 ---
MOON -------- SolSys 11 Jan - 11 Jan 1996 ---
Survey -------- ---- 11 Jan - 12 Jan 1996 CAL
NGC 5457 M 101 Glxy 12 Jan - 13 Jan 1996 ---
RE J0751+144 EUVE J0751+147 CV 13 Jan - 19 Jan 1996 ---
ALEXIS Transient -------- NOID 19 Jan - 21 Jan 1996 ---
QSO 1334+246 IRAS 13349+2438 QSO 21 Jan - 21 Jan 1996 ---
EUVE J0311-318 -------- NOID 21 Jan - 21 Jan 1996 ---
LHS 5142 LP 606-35 M+ 21 Jan - 21 Jan 1996 RAP
theta 1 Tau EUVE J0428+159 K0IIIb 21 Jan - 27 Jan 1996 ---
1121+422 -------- AGN 21 Jan - 27 Jan 1996 RAP
EUVE J1127+42.1 -------- NOID 21 Jan - 27 Jan 1996 RAP
beta CMa Tunnel -------- Bkgd 27 Jan - 30 Jan 1996 ---
theta 1 Tau EUVE J0428+159 K0IIIb 30 Jan - 01 Feb 1996 ---
===================================================================
Key to Notes:
RAP = simultaneous Right Angle Program imaging observation
1. Science News
===============
1.1 Recent EUVE Science Highlights
----------------------------------
by Dr. Pierre Chayer, EUVE/CEA Scientist
EUVE Analysis of GD 50
Drs. Stephane Vennes, Stuart Bowyer, and Jean Dupuis obtained and
analyzed the peculiar EUVE spectrum of the hot, hydrogen-rich white
dwarf, GD 50. Extreme ultraviolet (EUV) spectroscopy of this massive
white dwarf reveals an unusual photospheric mixture of hydrogen and
helium, showing a prominent He II resonance line series. Dr. Vennes
and his collaborators point out that the presence of helium in an
isolated, massive DA white dwarf is paradoxical, because radiative
levitation of helium is clearly undone by the high surface gravity
(log g = 9.0 for GD 50).
They propose two possible mechanisms to explain the presence of
helium in the photosphere of GD 50. They suggest that helium is
accreted from the ISM at the Bondi-Hoyle rate. But, because accretion
onto GD 50 would constitute a unique occurrence for a hot white dwarf,
they examined an alternative explanation. If massive white dwarfs do
result from stellar mergers, large orbital angular momentum may be
preserved and result in large meridional circulation current, possibly
dredging-up helium from the envelope. Although Dr. Vennes and his team
do find evidence of large rotational velocity in EUV He II line
profiles, they propose additional observational tests of the dredge-up
model.
1.2 Abstracts of Recently *Accepted* EUVE Papers
------------------------------------------------
Included below are abstracts of EUVE-related papers recently
*accepted* for publication. For those papers authored by CEA
personnel, the CEA publication numbers are indicated. Unless
otherwise noted, researchers may obtain preprints of the CEA papers by
sending an e-mail request containing the publication number(s) of
interest to pub@cea.berkeley.edu.
Researchers are encouraged to contribute *accepted* EUVE-related
abstracts for inclusion in future editions of this newsletter;
abstracts or preprints will also be posted under the CEA WWW Home
Page. Please send all abstracts or preprints to
archive@cea.berkeley.edu.
--------------------------------------------------------------
A TIME-RESOLVED, EXTREME-ULTRAVIOLET, SPECTROSCOPIC STUDY OF THE
QUIESCENT AND FLARING CORONA OF THE FLARE STAR AU MIC
B.C. Monsignori Fossi, M. Landini, G. Del Zanna, and S. Bowyer
To appear in The Astrophysical Journal. [CEA publication #718]
The extreme ultraviolet emission obtained during a 1992 July 14-17
observation of AU Mic has been studied with lines detected with the
short, medium, and long wavelength (SW, MW, LW) spectrometers on the
Extreme Ultraviolet Explorer (EUVE). The flares were observed during
this period. The time evolution of the differential emission measure
is presented. The synthetic spectrum derived from the differential
emission measure is compared with the observed data. An estimate of
the density and volume of the emitting plasma is obtained using Fe XXI
lines.
--------------------------------------------------------------
DISCOVERY OF PHOTOSPHERIC HELIUM IN THE ULTRA-MASSIVE DA WHITE DWARF
GD 50
S. Vennes, S. Bowyer, and J. Dupuis
To appear in The Astrophysical Journal Letters. [CEA publication #727]
Extreme ultraviolet (EUV) spectroscopy of the hot, hydrogen-rich
white dwarf GD 50 reveals an unusual photospheric mixture of hydrogen
and helium. This hot DA white dwarf is also remarkable for its mass
(~1.2 M_solar) near the Chandrasekhar limit. The spectra obtained with
the Extreme Ultraviolet Explorer (EUVE) show a prominent He II
resonance line series and constrain its atmospheric parameters to
T_eff = 40,300 +/- 100 K and n(He)/n(H) = (2.4 +/- 0.1)E-4 (assuming
log g = 9.0). We also constrain the local interstellar medium column
densities of neutral helium and hydrogen to n_HeI = 6E+16 and n_HI =
9E+17 cm^(-2). The presence of helium in an isolated, massive DA white
dwarf is paradoxical. We examine and rule out a few scenarios
(radiative levitation, accretion from the ISM or a hypothetical
companion), but we suggest that if massive white dwarfs do result from
stellar mergers, large orbital angular momentum may be preserved and
result in a large meridional circulation current, possibly dredging-up
helium from the envelope. Although we find evidence of large
rotational velocity in EUV He II line profiles, we propose additional
observational tests of the dredge-up model.
--------------------------------------------------------------
2. Science Operations News
==========================
2.1 Hot Spots in the SW Spectrometer
------------------------------------
by Dr. Damian Christian, ISO Observation Support Scientist
[Note: This memo was released to the egi mailing list on 12
Feb. -Ed]
During the last several observations it has been found that the
EUVE short-wavelength (SW) spectrometer contains recurring hotspots.
The position and intensity of the hotspots is variable, and they are
not always present. The purpose of this memo is to inform the GO
community of the hotspots and present methods for removing them using
the IRAF software.
Two of the more frequently occurring hotspots are found at or very
near (956, 1001) and (1591, 909) in X,Y detector coordinates. The
first hotspot is worrisome because it can fall on the spectrum near
114 Ang. For spiral dithered observations the spot is re-mapped over
a larger region of the spectrum. The pulse heights of the hotspots
are broad and can not be easily filtered by changing detector pulse
height thresholds. The spots can be effectively eliminated with the
IRAF software.
One method is to make a spatial filter which allows you to remove
events in a specific region. The way to do this is with a mask. The
task plcreate (found in xray.ximages) allows you to create a mask.
For example:
> plcreate "!BOX 956 1001 3 3" "2048 2048" hotspot.pl
will create a pixel mask which excludes the box with a height and
width of three centered at 956, 1001. See the plcreate help page for
details. You can display the .pl file as an image to make sure you
have the region you like (it should be 1 wherever pixels are kept and
0 where they are excluded). If you want to make more complex masks
(circles, etc.), see the help in the xray package on regions.
Once you have a mask, you apply it by coping the QPOE to a new
masked QPOE with qpcopy found in xray.ximages:
> qpcopy "sw.qp[key=(dx,dy),mask=hotspot.pl]" " " fixsw.qp
and then make an image of the new QPOE (fixsw.qp) in remapped
(default) coordinates and go from there.
If you have trouble with this procedure or have any other concerns
please contact the GO program at egoinfo@cea.berkeley.edu for
assistance.
2.2 Public Data Release for 1 Mar 1996
--------------------------------------
by Dr. Nahide Craig, ISO User Support Scientist
The table below lists the GO observations that become public on 1
Mar 1996. For each entry is given the target name, the approximate
exposure time in ksec, the GMT start and end date(s) for the
observation, the spectral type of the target, and the data
identification code. All public data sets can be ordered from the
archive via WWW and electronic or postal mail (see addresses below).
Please be sure to include in your order the DataID(s) of interest.
Processed data sets are shipped on 8mm tape (or, if requested, on
CD-ROM) via postal mail.
The data rights policy for GO observations states that GOs have
proprietary rights to the data for one year from the date (s)he
receives it. It is often the case that long observations are broken
up over many months; e.g., an observation approved for 60 ksec may
actually be observed for 10 ksec one month, 20 ksec the next and 30
ksec three months later. In such cases the one-year proprietary
period begins after the GO is sent the final piece of the completed
observation.
===============================================================
Target ~Exp Observation Date(s) SpT DataID
Name (ksec) Start End
===============================================================
Data Sets Available 1 Mar 1996:
CYG 1992 75 22 Nov - 25 Nov 1994 Nova go274
GJ 117 100 02 Dec - 05 Dec 1994 K1V go275
GJ 117 72 05 Dec - 08 Dec 1994 K1V go276
GD 50 61 12 Dec - 14 Dec 1994 DA go277
Moon 6 11 Dec - 12 Dec 1994 SolSys go278
PSR J0108-1431 100 08 Dec - 11 Dec 1994 Pulsar go279
PSR J0108-1431 2 11 Dec - 11 Dec 1994 Pulsar go280
PSR J0108-1431 48 24 Dec - 26 Dec 1994 Pulsar go281
YZ CMi 97 21 Dec - 24 Dec 1994 M4.5Ve go282
===============================================================
2.3 On-Line Access to EUVE
--------------------------
Listed below are the various methods for on-line access to EUVE:
o CEA World Wide Web (WWW)
URL http://www.cea.berkeley.edu/
telnet www.cea.berkeley.edu 200 (for those without a WWW browser)
o anonymous FTP
ftp ftp.cea.berkeley.edu
Name: anonymous
Password: type_your_full_e-mail_address
o anonymous gopher
gopher ftp.cea.berkeley.edu
o EUVE Electronic Newsletters
Past issues -- available via the CEA WWW site
Subscriptions -- mail majordomo@cea.berkeley.edu ("subscribe
euvenews")
Post message to all subscribers: mail euvenews@cea.berkeley.edu
o GI Program
Are you interested in finding out about or using EUVE data? Do
you need help in understanding EUVE data sets? Do you need help
in using the available EUVE data analysis software tools? If you
answer "yes" to any of the above, the Guest Investigator (GI)
Program at CEA can help YOU! For more information see the CEA
WWW site or contact the Archive (archive@cea.berkeley.edu).
o Public RAP
The Public Right Angle Program (RAP) is an easy method for
researchers to propose for long-exposure EUVE imaging data. For
more information on the Public RAP and the simple proposal
process see the CEA WWW site or contact the EGO Center
(egoinfo@cea.berkeley.edu). Mail all proposals to
euverap@cea.berkeley.edu.
o Contact information for the EUVE Science Archive or GO Center:
Center for EUV Astrophysics
2150 Kittredge St.
Berkeley, CA 94720-5030
Archive EGO Center
510-642-3032 (voice) 510-643-8727 (voice)
510-643-5660 (fax) 510-643-5660 (fax)
archive@cea.berkeley.edu egoinfo@cea.berkeley.edu
3. CEA Job Listings
===================
by Cathie Jones, CEA Personnel Manager
Programmer Analyst II, Job # 09-323-30 (full-time career position)
Serve as a software engineer at the Center for EUV Astrophysics.
Design prototype software systems for low cost automated satellite
operations and human computing. General programming areas will be
supporting Artificial Intelligence (AI) research in
model/rule/constraint-based reasoning as applied to orbiting vehicles
and data acquisition/control loops.
Qualifications include a strong background in Electrical
Engineering, Computer Science, Space Engineering, and/or Information
Systems, with proven software development experience required.
Experience with the design and implementation of AI software, and
orbiting vehicle ground/flight software design required. Experience
in a combination of the following: UNIX (SUN, SGI, HP), C, C++, LISP,
Fortran, and scripting; development of intelligent image processing
systems, fault diagnosis, fuzzy controllers, network algorithms and
protocols, network based parallel computing; product design
experience. CASE tool experience a plus. Experience with WWW
(Netscape, Mosaic), GUI development, windowing systems preferred.
To apply, formal resume must be submitted to:
Personnel Office #3540
Box 09-323-30
2200 University Ave.
Berkeley, CA 94720-3540
---------------------------------------------------------------------------
The EUVE Electronic Newsletter is issued by the Center for Extreme
Ultraviolet Astrophysics, University of California, Berkeley, CA
94720, USA. The opinions expressed are those of the authors. EUVE
Principal Investigators and Newsletter Publishers: Dr. R.F. Malina
and Professor S. Bowyer. ISO Manager and Newsletter Editor: B.A.
Stroozas. Funded by NASA contract NAS5-29298. Send newsletter
correspondence to ceanews@cea.berkeley.edu.
The EUVE project is managed by NASA's GSFC: Paul Pashby, GSFC
Project Manager; Dr. Yoji Kondo, Project Scientist; Dr. Ronald
Oliversen, Deputy Project Scientist; Mr. Kevin Hartnett, Project
Operations Director. NASA HQ: Dr. G. Riegler, Program Manager.
Information on the EUVE GO Program is available from Dr. Y. Kondo,
Mail Code 684, GSFC, Greenbelt, MD 20771 at (301) 286-6247 or e-mail
to euve@stars.span.nasa.gov.
END-----------EUVE------------ELECTRONIC---------------NEWS-------------END
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