ASTRONOMY & ASTROPHYSICS JUNE II 1997, PAGE 473

SUPPLEMENT SERIES

Astron. Astrophys. Suppl. Ser. 123, 473-485 (1997)

Library of high and mid-resolution spectra in the Ca ii H
& K, Hα, Hβ, Na i D1, D2, and He i D3 line regions of F,
G, K and M field stars?,??

D. Montes1, E.L. Mart́ın2, M.J. Fernández-Figueroa1, M. Cornide1, and E. De Castro1

1 Departamento de Astrof́ısica, Facultad de F́ısicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
2 Instituto de Astrof́ısica de Canarias, E-38200 La Laguna, Tenerife, Spain

Received June 17; accepted September 25, 1996

Abstract. In this work we present spectroscopic obser-
vations centered in the spectral lines most widely used
as optical indicators of chromospheric activity (Hα, Hβ,
Ca ii H & K, and He i D3) in a sample of F, G, K and M
chromospherically inactive stars. The spectra have been
obtained with the aim of providing a library of high and
mid-resolution spectra to be used in the application of
the spectral subtraction technique to obtain the active-
chromosphere contribution to these lines in chromospher-
ically active single and binary stars. This library can also
be used for spectral classification purposes. A digital ver-
sion with all the spectra is available via ftp and the World
Wide Web (WWW) in both ASCII and FITS formats.

Key words: atlas — stars: activity — stars: late-type —
stars: fundamental parameters — stars: general

1. Introduction

Enhanced emission cores in the Ca ii H & K, are the pri-
mary optical indicators of chromospheric activity in late-
type stars, but also the emission or the filling-in of the cen-
tral core of other lines such as Hα, Hβ, Na i D1, D2, and

Send offprint requests to: D. Montes (dmg@ucmast.fis.ucm.es)
? Based on observations made with the Isaac Newton tele-
scope and the William Herschel Telescope operated on the
island of La Palma by the Royal Greenwich Observatory at
the Spanish Observatorio del Roque de Los Muchachos of the
Instituto de Astrof́ısica de Canarias, and with the 2.2 m tele-
scope of the Centro Astronómico Hispano-Alemán of Calar
Alto (Almeŕıa, Spain) operated jointly by the Max Planck
Institut für Astronomie (Heidelberg) and the Spanish Comisión
Nacional de Astronomı́a.
?? The spectra of the stars listed in Table 3 are also avail-
able in electronic form at the CDS via anonymous ftp
to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-
strasbg.fr/Abstract.html

He i D3 indicate the existence of an active chromosphere
in these stars. Actually, the later mentioned lines are only
in emission in a few very active stars, whereas in a large
number of moderately active stars only a filling-in of the
photospheric absorption is present. To infer the chromo-
spheric activity level a comparison with non-active stars is
needed, for example by means of the spectral subtraction
technique. This technique provides reliable measurements
of the the active-chromosphere contribution to these lines
(see Montes et al. 1995a,c; and references therein). To ap-
ply this technique a large number of spectra of inactive
stars (i.e., stars with negligible Ca ii H & K emission)
with different spectral types and luminosity classes taken
with the same spectral resolution that of the stars under
consideration is needed.

Previously published stellar libraries cover the optical
range and extend to the near infrared, however they are
of poor spectral resolution. The more widely used have
the following wavelength ranges and spectral resolutions:
Gunn & Stryker (1983) (3130 − 10800 Å, 20 and 40 Å);
Jacoby et al. (1984) (3510−7427 Å, 4.5 Å); Pickles (1985)
(3600− 10000 Å, 15 Å); Kirkpatrick et al. (1991) (6300−
9000 Å, 8 and 18 Å); Silva & Cornell (1992) (3510−8930 Å,
11 Å); Torres-Dodgen & Weaver (1993) (5800 − 8900 Å,
15 Å); Danks & Dennefeld (1994) (5800−10200 Å, 4.3 Å);
Allen & Strong (1995) (5800− 10200 Å, 6 Å) and Serote
Roos et al. (1996) (4800 − 9000 Å, 1.25 and 8.5 Å). As
can be seen the higher spectral resolution is only 1.25 Å
(Serote Roos et al. 1996) and 4.5 Å (Jacoby et al. 1984)
that is much lower than needed in detailed spectroscopic
studies of chromospheric activity.

Our intent in this paper is to provide a library of higher
resolution spectra (≤ 0.5 Å) of F, G, and K chromospher-
ically inactive stars to be used in the application of the
spectral subtraction technique in chromospherically ac-
tive single and binary stars. These spectra can also be
used for spectral classification purposes (see Jaschek &
Jaschek 1990) and specially for the spectral classification



474 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

Table 1. Summary of high-resolution observations

Ca II H&K Hα Hβ D1, D2, D3

O Date Tel. Detector λi − λf δλ λi − λf δλ λi − λf δλ λi − λf δλ

1 Feb. 1988 2.2 m RCA 3890− 4009 0.198 - - - - - -
2 Jul. 1989 2.2 m RCA 006 3883− 4015 0.198 6464− 6719 0.50 - - - -
3 Dec. 1992 INT EEV5 3840− 4050 0.358 6507− 6764 0.45 4778− 4941 0.34 - -
4 Mar. 1993 2.2 m TEK #6 3830− 4018 0.420 - - - - - -
5 Jun. 1995 2.2 m RCA #11 - - 6510− 6638 0.26 4807− 4926 0.26 - -
6 Sep. 1995 INT TEK3 - - 6452− 6695 0.48 - - 5762− 6011 0.48

Table 2. Summary of mid-resolution observations

Hα Hα + Na I D1, D2

O Date Tel. Detector λi − λf δλ λi − λf δλ

7 Jan. 1993 WHT TEK1 - - 5500− 7000 2.90
8 Apr. 1993 INT EEV5 - - 5626− 7643 3.16
9 Jun. 1995 INT TEK3 6430− 6824 0.78 - -
10 Aug. 1995 INT TEK3 6295− 6918 1.06 - -
11 Nov. 1995 INT TEK3 6344− 6742 0.78 - -

of chromospherically active binary stars with composite
spectra (see Strassmeier & Fekel 1990). In addition, we
provide spectra of M-type stars with resolution signifi-
cantly higher than in previous databases (Jacoby et al.
1984; Kirkpatrick et al. 1991, 1995).

We present a total of 170 spectra centered in the spec-
tral lines most widely used as optical indicators of chro-
mospheric activity in a sample of 116 F, G, K and M field
stars.

In Sect. 2 we report the details of our observations and
data reduction. The library is presented in Sect. 3 with
comments on the behaviour of some interesting spectral
lines.

2. Observations and data reduction

The spectroscopic observations of inactive stars pre-
sented here were carried out during several observ-
ing seasons, from 1988 to 1995, within a program
devoted to the study of optical activity indicators
in chromospherically active single and binary stars
(Montes et al. 1994, 1995a-d, 1996a,b; Mart́ın & Montes
1997). The high and mid-resolution spectra were ob-
tained with three telescopes: the 2.2 m Telescope at the
German Spanish Astronomical Observatory (CAHA) in
Calar Alto (Almeŕıa, Spain), using a Coudé spectrograph
with the f/3 camera, the Isaac Newton Telescope (INT)
and the William Herschel Telescope (WHT) located at the
Observatorio del Roque de Los Muchachos (La Palma,
Spain), using the Intermediate Dispersion Spectrograph
(IDS) with the cameras 500 and 235 at the INT and the
ISIS double arm spectrograph at the WHT.

The different observational campaigns, the telescope
and detector used and the spectral region observed in each
season are given in Tables 1 and 2. We also give for each
spectral region the wavelength range (λi−λf ) covered and
the spectral resolution (δλ) achieved.

The spectra have been extracted using the standard
reduction procedures in the MIDAS and IRAF packages
(bias subtraction, flat-field division, optimal extraction
of the spectrum, and wavelength calibration using arc
lamps). More details of the observations and data reduc-
tion for the different observational seasons from 1988 to
1995 can be found in Fernández-Figueroa et al. (1994);
Mart́ın et al. (1994) and Montes et al. (1995a-d, 1996b).

The high-resolution observations cover four spectral
ranges:

1. The Ca ii H (3968.47 Å) & K (3933.67 Å) line region,
that also includes the Hε (3970.07 Å) and in some cases
the Hζ (3889 Å) and Hη (3835 Å) Balmer lines.

2. The Hα (6562.8 Å) line region that in some observa-
tional seasons also include the Li i 6708 Å line and the
Fe i 6663 Å, Fe i 6678 Å and Ca i 6718 Å lines used in
rotational velocity determinations (Huisong & Xuefu
1987).

3. The Hβ (4861.32 Å) line region.
4. The He i D3 (5876 Å) line region that also includes the

Na i D1 (5895.92 Å) and D2 (5889.95 Å) lines.

We measured the resolution of our spectra using emis-
sion lines of arc lamps taken on the same nights. Typically
the full width at half maximum (FWHM) was two pixels.
The spectral resolution (δλ) achieved ranges between 0.2
and 0.5 Å (R = λ/δλ, 25000− 10000) depending on the
observational season (see Table 1).



D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 475

The mid-resolution observations (δλ between 0.8 and
3 Å) cover, in some cases, the Hα line region and in other
cases the Hα and Na i D1 and D2 line region (see Table 2).

In the Hα, Hβ, and Na i D1, D2, and He i D3 line re-
gions the spectra have been normalized by fitting a poly-
nome to the observed continuum. However, in the Ca ii H
& K line region it is very difficult to fit a continuum so
the spectra have been normalized to the measured flux in
a 1 Å window centered at 3950.5 Å. This reference point
at 3950.5 Å is not a real continuum, but it is a relatively
line-free region that could be used as a pseudo-continuum
to normalize all the Ca ii H & K spectra and that has been
used by Pasquini et al. (1988) to develop a calibration pro-
cedure for converting the observed line fluxes into absolute
surface fluxes. In the case of the mid-resolution spectra of
M stars it is also difficult to establish a continuum, due to
the presence of strong molecular bands, so we have nor-
malized these spectra by means of the pseudo-continuum
regions used by Mart́ın et al. (1996) located at 6525−6550,
7030 − 7050, and 7540 − 7580. At lower wavelengths we
included other two regions near 5795 and 6150 Å. We plot
the spectra normalized to those points in Fig. 6. However,
in the database available by ftp or WWW, we have di-
vided the spectra only by the average continuum level in
the region 6525−6550 Å in order to preserve the observed
shape.

3. The library

The stars included in the library have been selected from
the sample of lower main sequence stars studied in the
Mount Wilson Observatory HK project (Baliunas et al.
1995 and references therein). From this sample the slowly-
rotating stars and the stars with the lower Ca ii H & K
spectrophometric index S (normally lower than 0.2) were
chosen.

Several stars not included in the sample of the HK
Project have been observed, because there are known to
be inactive and slowly rotating stars and they were used
by other authors in the application of the spectral subtrac-
tion technique (see Strassmeier et al. 1990; Strassmeier &
Fekel 1990; Hall & Ramsey 1992). Some visual compan-
ions of chromospherically active binaries have been ob-
served simultaneously by locating both components of the
visual par in the slit when the spectra where taken. Some
of these stars are inactive ADS 1697 B (HD 13480) and
some are little active ADS 16557 A (HD 218739), σ1 CrB,
and ADS 8119 A (HD 98231) (see Table 3).

We have considered as chromospherically inactive
stars, those which at our spectral resolution do not
present any evidence of emission in the core of Ca ii H
& K lines. We have found that some stars of the HK
project (HD 115417, HD 115383, HD 206860, HD 101501,
HD 4628, HD 16160) with relatively low values of S index
(0.2 − 0.3) present a small, but measurable, emission in

our Ca ii H & K spectra (see Montes et al. 1995c). Hence,
they have not been used as reference stars.

Table 3 presents information about the observed stars.
In this table we give the HD and HR numbers, name, spec-
tral type and luminosity class (Tsp), from the Bright Star
Catalogue (Hoffleit & Jaschek 1982; Hoffleit & Warren
1991), the Catalogue of Nearby Stars (Gliese & Jahreiss
1991), and Kirkpatrick et al. (1995), metallicity [Fe/H]
(from Taylor 1994, 1995), rotational period (Prot) and
v sini (from Donahue 1993; Baliunas et al. 1995). The Tsp

given between brackets are from Hoffleit & Warren (1991)
and the values of v sini marked with “*” are from the ref-
erences given in Strassmeier & Fekel (1990). We also give
the Ca ii H & K spectrophometric index S from Baliunas
et al. (1995) or from Duncan et al. (1991) (values with
“*”). In the columns labeled with Hα, He i D3, Hβ, and
Ca ii we list information about the observations for each
spectral range, using a code given in the first column of
Tables 1 and 2. In the last column “A” and “R” mean
active and reference star respectively, according with our
above mentioned criterion, and “E” means that the Hα
line is in emission in our spectra. In some cases, we have
available spectra of several stars that have been classi-
fied with the same spectral type, these spectra present
small differences in the lines that could be attibuted to
differences in metallicities, rotation, errors in the spectral
classification, or even to variations in the small level of
activity that these stars could present.

Figures 1, 2, 3, and 4 show representative high-
resolution spectra in each spectral range. In these figures
we plot, at the left, the complete wavelength range covered
in each spectrum. For a better display of the spectral fea-
tures an small region of 30 Å centered in the spectral line
of interest in each case is showed at the right. Figure 5
presents mid-resolution spectra centered in the Hα line
from 6340 to 6740 Å, and Figure 6 shows representative
mid-resolution spectra in the wavelength range 5700 to
7600 Å which include the Na i D1, D2 and Hα lines. The
stars in these figures are arranged in order of spectral type
from F to M. The HD number and the spectral type of
the stars are given in each spectrum.

Looking at Figs. 1, 2, 3, and 4 some conclusions con-
cerning the behaviour of different spectral lines present in
each spectral region can be obtained.

In the Ca ii H & K line region, we can note the effect of
the spectral type: the equivalent width of several metallic
lines increases with decreasing temperature, in particular
the Al i 3961.52 Å line (see Fig. 1).

In the case of the Hα line, we note the increasing line
wings with hotter spectral type. At spectral type F the
line exhibits extended wings that decrease with decreasing
temperature. The line becomes sharper at spectral type
K (see Fig. 2). Some strong absorption lines in this spec-
tral region, that could be used for radial and rotational
velocity determinations are: the Fe i 6495 Å, 6546.25 Å,
6663.4 Å, and 6677.9 Å lines and the Ca i 6718 Å line.



476 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

Table 3. Stellar parameters and spectral region observed

HD HR Name Tsp [Fe/H] Prot v sini S Hα He I D3 Hβ Ca II A/R

(dex) (days) (km s−1)
F stars

161023 6600 - F0V - - < 15 - 9
177552 7231 - F1V - - 45 - 9
178476 7363 - F3V 0.170 - 50 - 9
185395 7469 θ Cyg F4V 0.009 - 3.4* - 5 5
13480B 642B 6 Tri B F5V - 2.236 - - 3 R
179422 7280 - F5V - - 40 - 9
176095 7163 - F5IV - - < 10 0.202 9
120136 5185 τ Boo F6IV 0.096 - 10.0 0.191 2 R
82328 3775 θ UMa F6IV −0.172 - 6.4* 0.182* 3
124850 5338 ι Vir F6III −0.129 - 15.0 0.210 2 R
187013 7534 17 Cyg F7V −0.109 - 10.0 0.154 2 R
212754 8548 34 Peg F7V −0.061 - 10.0 0.140 2 R
25998 1278 50 Per F7V - 2.6 20.0 0.300 3
216385 8697 σ Peg F7IV −0.297 - 10.0 0.142 2 R
167588 6831 - F8V - - < 6 - 10 -
6920 340 44 And F8V −0.230 15.3 < 15 0.194 3 R
45067 2313 - F8V - - < 15 0.141* 1 R
107213 4688 9 Com F8V 0.154 - 10.0 0.135 1 R
142373 5914 χ Her F8V −0.431 - 10.0 0.147 2 2 R
187691 7560 o Aql F8V 0.059 - 5.0 0.148 2 R
194012 7793 - F8V - - 5.0 0.198 2 2 R
136202 5694 5 Ser F8III-IV −0.075 - 5.0 0.140 2 2 R
154417 6349 V2213 Oph F8.5IV-V 0.099 7.78 5.0 0.269 2 2 A
43587 2251 - F9V - - 5.0 0.156* 1 R
78366 3625 - F9V - 9.67 5.0 0.248 8 -

G stars

115383 5011 59 Vir G0V 0.130 3.33 5.0 0.313 2 A
152792 - - G0V −0.462 - - - 2 R
114710 4983 β Com G0V (F95V) 0.135 12.35 3.9* 0.201 2 R
206860 8314 HN Peg G0V - 4.86 10.0 0.330 2 2 A
29645 1489 - G0V 0.074 - < 15 0.140 1 R
13974 660 δ Tri G0V (G0.5V) −0.444 - 10.0 0.232* 3 R
98231 4375 ξ UMa A G0V −0.352 - < 15 - 1 A
218739 - ADS 16557 A G0V - - - 0.294* 3 3 A

39587 2047 χ1 Ori G0V −0.084 5.36 10.0 0.325 3
13421 635 64 Cet G0IV - - < 15 0.131 1,3 R
190406 7672 15 Sge G1V - 13.94 5.0 0.194 2 2 R

146362 6064 σ1 CrB G1V - - < 30 0.264* 1 A
33021 1662 13 Ori G1IV - - 5.0 - 3
- - Sun G2V 25.72 <1.7 0.179 5 4 R
143761 5968 ρ CrB G2V (G0V) −0.185 - 5.0 0.150 2 5 2 R
81809 3750 - G2V −0.319 40.20 10.0 0.172 1 R
9562 448 - G2IV 0.147 - < 15 0.136 6 6 3 R
12235 582 112 Psc G2IV - - < 15 0.160 3 R
217014 8729 51 Peg G2.5IV −9.000 - 2 0.149 2 R
186427 7504 16 Cyg B G2.5V −0.002 - 3.0 0.145* 8 -
159222 6538 - G5V - - - 0.164* 10 -

20630 996 κ1 Cet G5V 0.133 9.24 5.6* 0.366 6 6 3 A
25680 1262 39 Tau G5V - - 3.0 0.281* 11 -
68255 3210 16 Cnc C G5V - - - - 8 -
78715 3640 79 Cnc G5III - - - - 8 -
115617 5019 61 Vir G6V 0.032 - 2.0* 0.162 1 R
190360 7670 - G6IV+M6V −9.000 - - 0.146 2, 6 6 2 R
3443 159 - G8V −0.101 - 2: 0.183 11 -
182488 7368 - G8V - - - 0.155* 2 R
131156 A 5544 A ξ Boo A G8V −0.151 6.31 3 0.461 2 2 A
144287 - GJ609.2 G8V - - - 0.156* 2 2 R
101501 4496 61 UMa G8V −0.070 16.68 < 15 0.311 3, 8 4 A
182572 7373 31 Aql G8IV - - < 15 0.148 2 R
188512 7602 β Aql G8IV - - 2.6 0.136 5 5 2 R
158614 6516 - G8IV (G9IV-V) 0.056 - - 0.158 2 R
62345 2985 κ Gem G8III - - 6* 0.123* 3
107383 4697 11 Com G8III - - < 19 - 8 -
215665 8667 λ Peg G8IIIa - - < 19 0.108 2 2 R
104979 4608 o Vir G8IIIa - - < 19 - 4 R
58368 - - G8IIIb - - - - 4 R
218356 8796 56 Peg G8Ib - - < 17 0.686 2 2 A
199939 - - G9III - - - - 2 2 A
201657 - - G9III - - - - 2 2 A
101013 4474 - G9III - - - - 4 R



D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 477

Table 3. continued

HD HR Name Tsp [Fe/H] Prot v sini S Hα He I D3 Hβ Ca II A/R

(dex) (days) (km s−1)
K stars

166 8 - K0V - - - 0.486* 11 -
3651 166 54 Psc K0V −9.000 48.00 - 0.176 3 R
185144 7462 61 Dra K0V −0.045 - 1.5* 0.215 8 -
23249 1136 δ Eri K0IV - - 2.2* 0.137 6 6
45410 2331 6 Lyn K0III-IV - - - 0.127* 3
25604 1256 37 Tau K0III - - - 0.105* 10, 11 -
62509 2990 β Gem K0III - - 2.5* 0.140* 3
109345 4784 - K0III - - - - 8 -
139195 5802 16 Ser K0III - - < 17 - 4 R
164349 6713 93 Her K0.5IIb - - < 17 - 2 2 A
190404 - GJ 778 K1V −0.087 - - 0.174* 2 2 A
10476 493 107 Psc K1V −0.123 35.2 < 20 0.198 11 3 R
22072 1085 - K1IV (G7V) - - - 0.131 6 6 1 R
142091 5901 κ CrB K1IV - - 4.5* - 5 5 4 R
95345 4291 58 Leo K1III - - < 19 - 4 R
163770 6695 θ Her K1IIa - - < 19 - 2 2 A
22049 1084 ε Eri K2V −0.165 11.68 < 15 0.496 3 A
4628 222 - K2V −0.235 38.5 - 0.230 11 3 3 A
166620 6806 - K2V −0.114 42.4 2.5* 0.190 8 -
12929 617 α Ari K2III - - < 17 0.118* 6 6
26162 1283 43 Tau K2III - - - - 11 -
190608 7679 16 Sge K2III - - < 19 - 8 -
206778 8308 ε Peg K2Ib - - < 17 0.330 2 2 A
16160 753 - K3V −0.297 48.0 - 0.226 6, 11 6 3 A
219134 8832 - K3V −9.000 - - 0.230* 2 A
115404 - GJ 505A K3V (K1V) - 18.47 - 0.535 2 A
127665 5429 ρ Boo K3III 0.183 - < 15 - 4 A
131156 B 5544 B ξ Boo B K4V - 12.28 20 1.381 2 A
131873 5563 β UMi K4III - - < 17 - 2 2 A
201091 8085 61 Cyg A K5V - 35.37 10 0.658 2, 8 2 A
201092 8086 61 Cyg B K7V - 37.84 < 25 0.986 2, 8 2 A

M stars

79210 - GJ 338 A, LHS 260 M0V - - - 2.113 8 -
79211 - GJ 338 B, LHS 261 M1III - - - 1.955 8 -
331161 - GJ 767 A, LHS 3482 M0.5V - - - - 8 -
189319 7635 12 Sge M0III - - < 17 0.254 8 -
- - GJ 767 B, LHS 3483 M2V - - - - 8 -
190658 7680 - M2.5III - - - - 8 -
- - GJ 569 A M3V - - - - 8 E
189577 7645 13 Sge M4IIIa - - - - 8 -
- - GJ 402, LHS 294 M4V M5V - - - - 8 -
- - GJ 406, LHS 36 M6V - - - - 8 E
- - GJ 1111, LHS 248 M6.5V - - - - 7 E
- - LHS 2243 M8V - - - - 7 E
84748 3882 R Leo M8IIIe - - - - 8 -
- - GJ 569 B M8.5V - - - - 8 -
- - LHS 2065 M9V - - - - 7 E
- - LHS 2924 M9V - - - - 7 E

The intensity of these lines increases toward later spec-
tral types, in particular the Hα, Fe i 6495 Å ratio has
been used as a spectral classification criterion (Danks &
Dennefeld 1994).

The Hβ line presents a marked temperature effect in
the wings (see Fig. 3) in the same way as the Hα line. The
Fe i 4878.08 Å line is an isolated and strong absorption line
in this spectral region that could be used for radial and
rotational velocity determinations.

The He i D3 line region also includes the Na i D1

and D2 lines, which are well known temperature and lu-
minosity discriminants among late-type stars, and they
show the expected trend of metallic-line intensity in-
creasing with decreasing temperature (O’Connell 1973;
Torres-Dodgen & Weaver 1993; Danks & Dennefeld 1994;

Serote Roos et al. 1996). The effect is more important
in the later spectral types and especially in the wing of
the lines (see Fig. 4). The behaviour of these lines con-
firms the spectral classification of the star HD 22072 as
G7V (Baliunas et al. 1995) rather than the K1V given
by Hoffleit & Jaschek (1982). These Na i resonance lines
are collisionally-controlled in the atmospheres of late-type
stars and have been observed in emission or filled-in in
very active red dwarf flare stars (Pettersen et al. 1984;
Pettersen 1989), so the spectra of the inactive stars pre-
sented here can be used to apply the spectral subtrac-
tion technique to other active stars and obtain information
about chromospheric emission in these lines (see Montes
et al. 1996b).



478 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

In the mid-resolution spectra (Figs. 5 and 6) in addi-
tion to the Na i D1, D2, Hα and the other lines above de-
scribed, we can also see other interesting features such as
Fe i 6411.66 Å, Fe i 6430.85 Å, and Ca i 6439.08 Å nor-
mally used for the application of the Doppler imaging
technique (see Fig. 5) and the Ca i (6122 and 6162 Å) lines
which are very weak at spectral type F and increase in
strength with decreasing temperature (see Fig. 6). From
mid K through M stars we can also see absorption molec-
ular bands of TiO in the following regions (5847− 6058),
(6090− 6390), (6651− 6852), (7053− 7270) and of CaH
in (6346, 6482, 6389) and (6750− 7050) (see the K and
M stars in Fig. 6). These molecular bands become very
strong at the later M spectral types, and dominate the
spectrum of these stars. For spectral type M7 or later the
VO absorption band (7400 − 7510) is also present. This
feature can be used as an additional spectral classifier in
the later spectral types, because it is strongly dependent
on temperature (Kirkpatrick et al. 1995). Finally, we note
in Fig. 6 the strong telluric line O2 (6867 Å), and the very
deep atmospheric B-band absorption feature at 7600 Å.

In order to enable other investigators to make use of
the spectra of this library, all the spectra of the stars listed
in Table 3 are available as FITS and ASCII format files
at the CDS in Strasbourg, France, via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5). They are also available
via the World Wide Web at:
http://www.ucm.es/OTROS/Astrof/fgkmsl/fgkmsl.html

Acknowledgements. This research has made use of the
SIMBAD data base, operated at CDS, Strasbourg, France. We
wish to thank the staff of Calar Alto and La Palma observa-
tories for their efficient assistance. We have made use of the
La Palma ING data archive for retrieving some spectra. This
work has been supported by the Universidad Complutense de
Madrid and the Spanish Dirección General de Investigación
Cient́ıfica y Técnica (DGICYT) under grant PB94-0263.

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D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 479

Fig. 1. High-resolution spectra in the Ca ii H & K line region



480 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

Fig. 2. High-resolution spectra in the Hα line region



D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 481

Fig. 3. High-resolution spectra in the Hβ line region



482 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

Fig. 4. High-resolution spectra in the Na i D1, D2, and He i D3 line region



D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 483

Fig. 5. Mid-resolution spectra in the Hα line region in the wavelength range 6340 to 6740 Å



484 D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars

Fig. 6. Mid-resolution spectra in the Na i D1, D2, and Hα line region, in the wavelength range 5650 to 7640 Å



D. Montes et al.: Library of high and mid-resolution spectra of F, G, K and M stars 485

Fig. 6. continued