Big science with 2-m class telescopes in a global network
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| Published in: | Кинематика и физика небесных тел |
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| Date: | 2003 |
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Головна астрономічна обсерваторія НАН України
2003
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| Cite this: | Big science with 2-m class telescopes in a global network / A.P. Hatzes, D.E. Mkrtichian // Кинематика и физика небесных тел. — 2003. — Т. 19, № 4-додаток. — С. 59-64. — Бібліогр.: 6 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859672368501227520 |
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| author | Hatzes, A.P. Mkrtichian, D.E. |
| author_facet | Hatzes, A.P. Mkrtichian, D.E. |
| citation_txt | Big science with 2-m class telescopes in a global network / A.P. Hatzes, D.E. Mkrtichian // Кинематика и физика небесных тел. — 2003. — Т. 19, № 4-додаток. — С. 59-64. — Бібліогр.: 6 назв. — англ. |
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| container_title | Кинематика и физика небесных тел |
| first_indexed | 2025-11-30T14:33:28Z |
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BIG SCIENCE WITH 2-m CLASS TELESCOPESIN A GLOBAL NETWORKA. P. Hatzes1, D. E. Mkrti
hian2
20031Th�uringer Landessternwarte Tautenburg, Germanye-mail: artie�tls-tautenburg.de2Astronomi
al Observatory, Odessa National UniversityShev
henko Park, 65014 Odessa, Ukrainee-mail: davidm�te.net.uaÍÎÂÛÅ �Î�ÈÇÎÍÒÛ ÄËß 2-ÌÅÒ�ÎÂÛÕ ÒÅËÅÑÊÎÏΠ �ËÎÁÀËÜÍÎÉ ÑÅÒÈ,Õàòöåñ À. Ï., Ìêðòè÷ÿí Ä. Å. � Àñòðîñåéñìîëîãèÿ è ïîèñê âíåñîëíå÷íûõ ïëàíåò � ýòî äâàèññëåäîâàòåëüñêèõ íàïðàâëåíèÿ, òðåáóþùèõ çíà÷èòåëüíûõ ðåñóðñîâ íàáëþäàòåëüíîãî âðåìå-íè, êîòîðîå ñëîæíî ïîëó÷èòü íà òåëåñêîïàõ ñ áîëüøèìè àïåðòóðàìè. Íà ìàëûõ æå òåëåñêî-ïàõ êëàññà 2-ìåòðîâûõ ïðåäîñòàâëÿåòñÿ äîñòàòî÷íîå êîëè÷åñòâî íàáëþäàòåëüíîãî âðåìåíè,ê òîìó æå ñ áîëåå ãèáêèì ðàñïèñàíèåì. Èñïîëüçóÿ íåñêîëüêî òàêèõ òåëåñêîïîâ â ãëîáàëüíîéñåòè, ìîæíî ñóùåñòâåííî ïðîäâèíóòüñÿ âïåðåä â èññëåäîâàíèÿõ ïî íàçâàííûì íàïðàâëåíè-ÿì.  äàííîé ñòàòüå ìû ïðåäñòàâëÿåì íåêîòîðûå ðåçóëüòàòû, ïîëó÷åííûå íà 2-ì òåëåñêîïàõïî ïðîãðàììàì âûñîêîòî÷íîãî èçìåðåíèÿ ðàäèàëüíûõ ñêîðîñòåé â çàäà÷àõ èçó÷åíèÿ âíåñîë-íå÷íûõ ïëàíåò è ñåéñìîëîãèè ïóëüñèðóþùèõ çâåçä. Òàêæå îáñóæäàåòñÿ âîçìîæíûé âêëàäãëîáàëüíîé ñåòè 2-ì òåëåñêîïîâ â ðåøåíèå ýòèõ çàäà÷.Asteroseismology and the sear
h for extrasolar planets are two fields of resear
h whi
h require
onsiderable teles
ope resour
es that are diffi
ult to obtain on large aperture teles
opes. Small,2-m
lass teles
opes provide substantial amount of time resour
es with more flexible s
heduling.Using several of these fa
ilities in a global network
an make signifi
ant
ontributions to both ofthese fields. We present some results of pre
ise radial velo
ity programs on extra-solar planetsstudies and seismology of pulsating stars obtained on 2-m
lass teles
opes and dis
uss the s
ientifi
impa
t of a probable Global Network of 2-m
lass teles
opes for these studies.INTRODUCTIONTo date there are about ten teles
opes in operation throughout the world with apertures greaterthan 8 m. Although these fa
ilities are produ
ing ex
iting results in observational astrophysi
s, theyhave not eliminated the need for 2{3-m
lass teles
opes. S
ienti�
programs requiring large amountsof teles
ope time are best suited for small teles
opes as time on the larger fa
ilities is expensive andover-subs
ribed. Two s
ienti�
programs that are ideal for small teles
opes are radial velo
ity sear
hesfor extrasolar planets and investigations of pulsating stars. We present here observations of extra-solarplanets and pulsating stars taken with high-resolution spe
trographs that demonstrate the
apabilitiesof small teles
opes. When organized into a global network small teles
opes
an have a major s
ienti�
impa
t and provide s
ienti�
results that are not possible on large teles
opes.2-m TELESCOPES IN A GLOBAL NETWORKTwo-meter
lass teles
opes have a distin
t advantages over 8{10m
lass teles
opes in that they
anmore easily (and inexpensively) be organized into a global network well distributed in longitude. This
an provide
ontinuous
overage of target obje
ts whi
h is important for studies of pulsating stars inorder to remove the one day alias present in data from one site. The extended
overage is also essentialto resolve the �ne splitting of modes ne
essary to yield information about the stellar stru
ture.The map in Fig. 1 shows the world-wide distribution of potential 2-m
lass teles
opes equippedwith high-resolution (R � 60 000) spe
trographs that
an be used for extended RV studies of pulsatingstars. Su
h a network
an also have a major impa
t in extra-solar planet studies and other �elds thatrequire time-resolved or synopti
studies (e.g., Doppler imaging studies of spotted stars).59
372
7/6
2+3
,17
0F'2
2$2
%2$2
Figure 1. The lo
ation of 2-m
lass teles
opes throughout the world that are equipped with high resolutionspe
trographs that
ould parti
ipate in a global network. M
DO: the M
Donald Observatory, Texas, USA; INT:the Isaa
Newton Group of Teles
opes, La Palma; OHP: Observatoir Haut Proven
e, Fran
e; TLS: Th�uringerLandessternwarte, Germany; PTO: the Terskol Observatory, Russia; BOAO: the Bohyunsan Opti
al AstronomyObservatory; OAO: the Okayama Astronomi
al Observatory, JapanPRECISE RADIAL VELOCITIES WITH AN IODINE GAS CELLMany programs require the pre
ise measurements of relative stellar radial velo
ities (RV). An iodinegas absorption
ell is a
onvenient and inexpensive means of
onverting any high resolution spe
tro-graph into pre
ise radial velo
ity instrument. The
ell when pla
ed in the opti
al light path produ
esa set of iodine absorption lines that are superimposed on the stellar spe
trum (see Fig. 2). The ve-lo
ity shifts of the star are measured with respe
t to the �xed pattern of the iodine spe
trum whi
hminimizes instrumental shifts. This te
hnique is
apable of a
hieving an RV pre
ision of 3 m/s, evenfor spe
trographs that were not designed to a
hieve su
h RV pre
ision.SEARCHES FOR EXTRA-SOLAR PLANETSThe existen
e of giant planets in orbit around other stars is undoubtedly one of the more importantastronomi
al dis
overies of the past de
ade. Most of these dis
overies were made with 2{3-m
lassteles
opes (see review by Mar
y & Butler [4℄). Fig. 3 shows radial velo
ity measurements for two knownextrasolar planets made with the TLS 2-m teles
ope + e
helle spe
trograph (R = 67 000). The TLSe
helle spe
trograph+iodine
ell
an a
hieve an RV pre
ision of 2{3 m/s. When the spe
trographwas
onstru
ted it was not envisioned that su
h high pre
ision RV measurements would be madewith it. The fa
t that it is
apable of making state-of-the-art RV measurements is a testament tothe wavelength stability provided by the iodine absorption
ell.PULSATING K GIANT STARSThe K giant stars are a new
lass of multi-periodi
variable stars that vary on times
ales of days tohundreds of days [1, 2℄. The long period variations are due either to surfa
e features, pulsations, orplanetary
ompanions, although re
ent RV studies suggest that planetary
ompanions may indeed bethe
ause of some long period variations found in these stars [6℄.60
0
.5
1
0
.5
1
5376 5377 5378 5379 5380 5381 5382 5383
0
.5
1
In
te
ns
ity
Figure 2. Spe
trum of iodine gas (upper panel), spe
trum of star (middle panel), spe
trum of star throughiodine gas (bottom panel)
-.5 0 .5 1 1.5
-500
0
500
Orbital Phase
R
V
(
m
/s
)
P = 3.31 days
-.5 0 .5 1 1.5
-100
0
100
55 CnC
Phase
R
V
(
m
/s
)
Phase
P = 14.6 dFigure 3. (Left) The radial velo
ity variations of � Boo due to a 3.9 MJupiter
ompanion in a 3.3 day orbit.Open
ir
les represent points that are replotted for another orbital
y
le. (Right) The radial velo
ity variationsof 55 Cn
due to a 0.84MJupiter
ompanion in a 14.6 day orbit. The s
atter about the orbital solution of thesemeasurements taken with the TLS 2-m teles
ope is 6.3 m�1
61
8786 8787 8788 8789 8790 8791 8792 8793
-200
-100
0
100
200
JD-2440000
R
ad
ia
l V
el
oc
ity
(
m
/s
)
Figure 4. The multi-mode pulsations in Ar
turus over eight
onse
utive nights based on data taken withthe M
Donald Observatory 2.1-m teles
ope. Crosses represent the data and the solid line represents a �t whi
his a sum of three periods: 2.46, 4.03, and 8.5 daysFig. 4 shows short period variations of Ar
turus (� Boo) taken over eight
onse
utive nights usingthe M
Donald Observatory 2.1-m teles
ope and an iodine gas
ell. The solid line represents a �tof three periods of 2.46, 4.03, and 8.5 days. So far 10 modes showing the equi-spa
ed frequen
yof p-modes have been found in this star [2, 5℄. The solid lines in Fig. 5 represent modes foundat the M
Donald Observatory in several 7-night observing runs. In spite of these many nights ofobservations not all modes were dete
ted. The dashed lines modes found by Merline [5℄ are based onmany more nights of data. The multi-modes that are present in K-giants are ideal for asteroseismi
studies, but the long periods and ri
h spe
trum of modes requires large amounts of observing time with
ontinuous monitoring. For instan
e the M
Donald data dete
ted di�erent modes on ea
h observingrun. The study of os
illations in K giants, many of whi
h are bright obje
ts, is ideally suited to2-m
lass teles
opes equipped with high resolution spe
trographs that
an devote the many
onse
utivenights needed to �nd all modes.RAPIDLY OSCILLATING Ap STARSThe rapidly-os
illating Ap (roAp) stars are a
lass of stars pulsating in p-modes with periods of6{12 minutes. Spe
tral studies show that the RV behavior of these stars
an be quite
omplex withindividual spe
tral lines showing RV pulsational amplitudes that are fa
tors of 10{100 times higherthan most spe
tral lines [3℄. Figure 6 shows the Fourier transform of RV measurements of the roAp starHD 134214 in seven spe
tral regions taken with the 2.1-m teles
ope at the M
Donald Observatory +Sandiford E
helle spe
trograph (R=50 000)+iodine
ell. The dashed line denotes the position ofthe known pulsation period. The pulsation RV amplitude strongly varies with the spe
tral region.These kinds of measurements are yielding valuable
lues about the verti
al stru
ture to the pulsa-tions in roAp stars. Figure 7 shows the RV variations for Nd II and Nd III lines in the roAp star 33 Libtaken with 2.7-m teles
ope at the M
Donald Observatory. The two spe
ies os
illate out-of-phase withea
h other. Sin
e Nd III is formed higher in the stellar atmosphere these data are eviden
e for a radialnode in a standing a
ousti
wave in the stellar atmosphere.The study of the verti
al stru
ture of pulsations in roAp stars requires the a
urate determinationof the phase and amplitude of individual spe
tral lines. These require a very long time sequen
e ofobservations. Furthermore, to remove the one day alias of one observing site that is needed to dete
tadditional modes
an only be done in a global network.
62
0 2 4 6 8 10
0
50
100
150
200
A
m
pl
itu
de
(
m
/s
)
0 2 4 6 8 10
0
50
100
150
200
Figure 5. The s
hemati
of pulsation frequen
y spe
trum of Ar
turus. Solid lines represents modes found atthe M
Donald Observatory (height indi
ates amplitude), dashed lines indi
ate the frequen
y (and not amplitude)of modes found by Merline [5℄
0
200
0
200
0
200
0
200
0
200
0
200
160 180 200 220 240 260 280 300 320 340
0
200
Frequency (c/d)
A
m
pl
itu
de
(
m
/s
)
HD 134214
Figure 6. The DFT spe
trum of RVs in HD134214 in seven spe
tral regions. The dashed line marks the lo
ationof the photometri
frequen
y. Note the di�erent pulsational amplitude in ea
h spe
tral regionCONCLUSIONThe pre
ise radial velo
ity measurements with a global network of 2-m
lass teles
opes will havea great s
ienti�
impa
t on studies of extra-solar planets and seismology of di�erent types of variablestars. For many of these programs the stars are bright, so a study with large teles
opes is notjusti�ed. Furthermore, to make signi�
ant progress in these �elds, parti
ularly in asteroseismology,many tens of
onse
utive nights, often in
oordinated multi-site
ampaigns are needed. This is simplynot possible on the larger teles
opes. The RV pre
ision of few m/s needed to make the breakthroughs63
Figure 7. The radial velo
ities of Nd II and Nd III lines in 33 Lib phased to the pulsational period. The twospe
ies are formed in di�erent heights in the stellar atmosphere and indi
ate the presen
e of a radial node tothe pulsationsin these ex
iting �elds is made possible by the iodine
ell te
hnique. Any teles
ope equipped witha high resolution spe
trograph
an join in a multi-site
ampaign. In the near future there are severalimportant spa
e missions for the photometri
study of extrasolar planets and pulsations (e.g., MOST,COROT, Eddington, Kepler). A global network of 2-m teles
opes for simultaneous ground-basedspe
tros
opi
studies
an provide essential data for the interpretation of the results from these spa
emissions.The 2-m teles
ope of the Terskol Observatory of ICAMER whi
h is lo
ated at the intermediategeographi
longitude in the
ontinent Eurasia is well suitable for parti
ipation in a global multi-sitehigh-resolution spe
tros
opi
ampaign to provide data in a key longitude gap. We intend to installan iodine-
ell in the
oude-room of this teles
ope and to test it for typi
al RV a
ura
ies during2002/2003 season.[1℄ Hatzes A. P., Co
hran W. D. Long-period radial velo
ity variability in three K giants // Astrophys.J.{1993.{41, N 3.{P. 339{348.[2℄ Hatzes A. P., Co
hran W. D. Stellar Os
illations in K Giants // Cool Stars Stellar Systems and the Sun /Eds. R. A. Donahue, J. A. Bookbinder.{ASP Conf. Ser.{1998.{154.{P. 311{326.[3℄ Kanaan A., Hatzes A. P. Pulsations and Radial Velo
ity Variations in Pulsating AP Stars. I. Analysis ofgamma Equulei // Astrophys. J.{1998.{503.{P. 848{856.[4℄ Mar
y G. W., Butler R. P. Planets Orbiting Other Suns // Publs Astron. So
. Pa
if.{2000.{112.{P. 137{140.[5℄ Merline W. J. Pre
ise Velo
ity Observations of K Giants: Eviden
e for Solar-like Os
illations in Ar
-turus // Pre
ise Stellar Radial Velo
ities / Eds. J. B. Hearnshaw, C. D. S
arfe.{ASP Conf. Ser.{1999.{170.{P. 187{192.[6℄ Setiawan J., Hatzes A., et al. Eviden
e of a Sub-stellar Companion around HD 47536 // Astron. andAstrophys.{2003.{in press. 64
|
| id | nasplib_isofts_kiev_ua-123456789-78599 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0233-7665 |
| language | English |
| last_indexed | 2025-11-30T14:33:28Z |
| publishDate | 2003 |
| publisher | Головна астрономічна обсерваторія НАН України |
| record_format | dspace |
| spelling | Hatzes, A.P. Mkrtichian, D.E. 2015-03-19T14:39:45Z 2015-03-19T14:39:45Z 2003 Big science with 2-m class telescopes in a global network / A.P. Hatzes, D.E. Mkrtichian // Кинематика и физика небесных тел. — 2003. — Т. 19, № 4-додаток. — С. 59-64. — Бібліогр.: 6 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/78599 en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел Workshop A1: Optical Telescopes and Facilities Big science with 2-m class telescopes in a global network Article published earlier |
| spellingShingle | Big science with 2-m class telescopes in a global network Hatzes, A.P. Mkrtichian, D.E. Workshop A1: Optical Telescopes and Facilities |
| title | Big science with 2-m class telescopes in a global network |
| title_full | Big science with 2-m class telescopes in a global network |
| title_fullStr | Big science with 2-m class telescopes in a global network |
| title_full_unstemmed | Big science with 2-m class telescopes in a global network |
| title_short | Big science with 2-m class telescopes in a global network |
| title_sort | big science with 2-m class telescopes in a global network |
| topic | Workshop A1: Optical Telescopes and Facilities |
| topic_facet | Workshop A1: Optical Telescopes and Facilities |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/78599 |
| work_keys_str_mv | AT hatzesap bigsciencewith2mclasstelescopesinaglobalnetwork AT mkrtichiande bigsciencewith2mclasstelescopesinaglobalnetwork |