A library of <i>H</i> band stellar spectra
for stellar population analysis purposes

Abstract. Using the VLT together with the near infrared instrument ISAAC, we have obtained medium spectral and high spatial resolution observations of a sample of nearby Seyfert galaxies in the H-band. This band is particularly suited for stellar population studies since the stellar component dominates over the AGN nucleus. The H-band also includes the peak contribution from cool stars. The AGN spectra are very rich in strong metallic lines which are sensitive to stellar luminosity class. For 4 out of 5 galaxies the central velocity dispersions are found to be significantly lower than reported in previous studies. Gradients in the stellar population within the central regions were searched for, together with evidence for dilution of the stellar spectral features within the nucleus.

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“…These stars extend the stellar library published in Dallier et al (1996). Figures A.1 and A.2 show the individual flux calibrated spectra.…”

Section: Appendix A: Starsmentioning

confidence: 80%

Near IR spectroscopy of active galactic nuclei

Boisson¹,

Coupé²,

Cuby

et al. 2002

A&A

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“…The strongest features are the CO absorption bands in both the H and K-band atmospheric windows. They originate in K and M stars, as can be seen from the libraries of stellar spectra described by Lancon & Rocca-Volmerange (1992), Origlia et al (1993), Dallier et al (1996), Meyer et al (1998), Wallace &Hinkle (1997), andFörster Schreiber (2000). A number of weaker metal absorption features are visible as well: Sii at 1.589 μm, Mgi at 1.711 μm, Nai at 2.206 and 2.209 μm, and Cai at 2.261, 2.263, and 2.266 μm.…”

Section: General Appearance Of the Spectramentioning

confidence: 98%

Early-type galaxies in the near-infrared: 1.5–2.4 $\mu{\rm m}$ spectroscopy

Cesetti

Ivanov

Morelli

et al. 2009

A&A

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Context. Near-infrared (hereafter NIR) data may provide complementary information to the traditional optical population synthesis analysis of unresolved stellar populations because the spectral energy distribution of the galaxies in the 1-2.5 μm range is dominated by different types of stars than at optical wavelengths. Furthermore, NIR data are less affected by dust absorption and hence could constrain the stellar populations in dust-obscured galaxies. Aims. We attempt to develop observational constraints on the stellar populations of unresolved stellar systems in the NIR. Methods. To achieve this goal, we require benchmark NIR spectra of "simple" early-type galaxies, to test and calibrate the outputs of population synthesis models. We obtained low-resolution (R ∼ 1000) long-slit spectra between 1.5 and 2.4 μm for 14 nearby earlytype galaxies using SofI at the ESO 3.5-m New Technology Telescope and higher resolution (R ∼ 3000) long-slit spectra, centered on Mgi at ∼1.51 μm for a heterogeneous sample of 5 nearby galaxies observed with ISAAC at Antu, one of the 8.2-m ESO Very Large Telescope. Results. We defined spectral indices corresponding to CO, Nai, Cai and Mgi absorption lines and measured their strengths in the galaxies spectrum. We defined a new global NIR metallicity index, suitable for abundance measurements in low-resolution spectra. Finally, we created an average-combined NIR spectrum of an early-type galaxy, from a homogeneous subset of our data set. Conclusions. The NIR galaxy spectra are similar to each other and some of the line index strengths correlate with both the iron abundance [Fe/H] and optical metal line indices of the galaxies. The data suggest that the NIR metal features, in combination with a hydrogen absorption feature, may break the age-metallicity degeneracy in a similar way the Mg and Fe features in the rest-frame optical wavelength range.

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“…4) were found in the spectrum; we identified them by comparison with spectra of late-M and early-L type photospheres. Both detections (S /N ≥ 3) and tentative detections of absorption features are listed in Table 7, following the spectral catalogues of Lançon & RoccaVolmerange (1992) and Dallier et al (1996; both papers discuss NIR spectra of O-to M-stars of luminosity classes I to V), Reid et al (2001) and Cushing et al (2005;both about M-and Ldwarfs).…”

Section: Absorption Features Towards Cb230-a: a Tentative Spectral Idmentioning

confidence: 99%

“…These were compared with known features of late-type dwarfs (class V) and giant (class III) stars: we must consider the latter stellar types in particular because the radius of the central protostar is expected to be larger, corresponding to a low surface gravity, which affects gravity-sensitive (2005), except for that of MgI at 1.18 μm, taken from the NIST atomic spectra database. The OH wavelengths are from Maillard et al (1976), while those of CO are from Dallier et al (1996) and Meyer et al (1998). b The equivalent widths were measured in the spectra after dereddening by using the visual extinctions derived from the [FeII] 1.645/1.321 line ratio (see Table 6); however, this should have little effect on the found values.…”

Section: Absorption Features Towards Cb230-a: a Tentative Spectral Idmentioning

confidence: 99%

The low-mass YSO CB230-A: investigating the protostar and its jet with NIR spectroscopy and Spitzer observations

Massi

Codella

Brand

et al. 2008

A&A

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Context. To investigate the earliest phases of star formation and study how newly-born stars interact with the surrounding medium, we performed a line and continuum survey at NIR and mm-wavelengths of a sample of relatively isolated Bok globules. Aims. We present a follow-up observational program of a star-forming site in the globule CB230. From narrow-band continuum observations of this site, we had discovered a bright [FeII] jet, which originates in the low-mass YSO CB230-A. We aim to investigate the physical properties of the region from where the jet is launched. Methods. Our analysis was carried out using low-resolution NIR spectra acquired with the camera NICS at the TNG telescope, with JH and HK grisms and a 1 arcsec-wide slit. These observational data were complemented with infrared photometric data from the Spitzer space telescope archive. Results. The relevant physical properties of CB230-A were constrained by SED fitting of fluxes from the NIR to the mm. The YSO spectrum exhibits a significant number of atomic and molecular emission lines and absorption features. The characteristics of this spectrum suggest that we are observing a region in the close vicinity of CB230-A, i.e. its photosphere and/or an active accretion disk. The spectra of the knots in the jet contain a large number of emission lines, including a rich set of [FeII] lines. Emission due to H 2 and [FeII] are not spatially correlated, confirming that [FeII] and H 2 are excited by different mechanisms, in agreement with the models where [FeII] traces dissociative J-shocks and molecular hydrogen traces slower C-shocks. By using intensity ratios involving density-sensitive [FeII] lines, we estimated the electron densities along the jet to be 6 × 10 3 -1 × 10 4 cm −3 . This indicates either high density post-shock regions of ionised gas or regions with a high degree of ionisation. Conclusions. By combining the present data with previously obtained maps at NIR-and mm-wavelengths, the emerging scenario is that CB230-A is a Class 0/I YSO driving an atomic jet that is observed to be almost monopolar probably due to its inclination to the plane of the sky and the resulting higher extinction of its red side. This primary jet appears to be sufficiently energetic to open the cavity visible in the NIR images and drive the large-scale molecular outflow observed at mm-wavelengths. CB230-A was revealed to be a good location to test the innermost structure of accreting low-mass protostars.

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A library of H band stellar spectra for stellar population analysis purposes

Cited by 34 publications

References 8 publications

Near IR spectroscopy of active galactic nuclei

Near IR spectroscopy of active galactic nuclei

Early-type galaxies in the near-infrared: 1.5–2.4 $\mu{\rm m}$ spectroscopy

The low-mass YSO CB230-A: investigating the protostar and its jet with NIR spectroscopy and Spitzer observations

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