Long-slit Mode Research Articles

Spectroscopy of the supernova H0pe host galaxy at redshift 1.78

Supernova (SN) H0pe was discovered as a new transient in James Webb Space Telescope (JWST) NIRCam images of the galaxy cluster PLCK G165.7+67.0 taken as part of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) JWST GTO program (ID 1176) on 2023 March 30. The transient is a compact source associated with a background galaxy that is stretched and triply imaged by the strong gravitational lensing of the cluster. This paper reports spectra in the 950–1370 nm observer frame of two of the galaxy images obtained with Large Binocular Telescope (LBT) Utility Camera in the Infrared (LUCI) in long-slit mode two weeks after the JWST observations. The individual and average spectra show the [O II] λλ3727,3730 doublet and the Balmer and 4000 Å breaks at redshift z = 1.783 ± 0.002. The code investigating galaxy emission (CIGALE) best-fit model of the spectral energy distribution indicates that the host galaxy of SN H0pe is massive (Mstar ≃ 6 × 1010 M⊙ after correcting for a magnification factor μ ∼ 7) with a predominantly intermediate-age (∼2 Gyr) stellar population, moderate extinction, and a magnification-corrected star formation rate ≃13 M⊙ yr−1, consistent with being below the main sequence of star formation. These properties suggest that H0pe might be a type Ia SN. Additional observations of SN H0pe and its host recently carried out with JWST (JWST-DD-4446; PI: B. Frye) will be able to both determine the SN classification and confirm its association with the galaxy analyzed in this work.

Characterization of the ASTRONIRCAM Spectral Mode

The algorithm for the reduction of spectroscopic observations with the ASTRONIRCAM camera-spectrograph installed at the 2.5-m telescope of the Sternberg Astronomical Institute of the Moscow State University is described. The instrument allows spectra of astronomical objects with long ( $$280^{\prime\prime}$$ ) and short ( $$10^{\prime\prime}$$ ) slits to be taken in the wavelength range from 1 to 2.5 $$\mu$$ m. The measured resolution reaches $$R=1270$$ for a $$0\overset{{}^{\prime\prime}}{.}9$$ slit; the light efficiency of the system changes from 6 to $$14\%$$ in the working wavelength range in the long-slit mode and from 1 to $$2\%$$ in the cross-dispersion mode. The transmission is limited by the quality of the grisms used. We have estimated the fraction of scattered light and studied the mechanical flexures and temperature drifts of the structure.

Integrated-light analyses vs. colour-magnitude diagrams

Context. Most of our knowledge of the stellar component of galaxies is based on the analysis of distant systems and comes from integrated light data. It is important to test whether the results of the star formation histories (SFH) obtained with standard full-spectrum fitting methods are in agreement with those obtained through colour-magnitude diagram (CMD) fitting (usually considered the most reliable approach). Aims. We compare SFHs recovered from the two techniques in Leo A, a Local Group dwarf galaxy most of whose stars formed during the last 8 Gyrs. This complements our previous findings in a field in the Large Magellanic Cloud bar, where star formation has been in progress since early epochs at varying rates. Methods. We have used GTC/OSIRIS in long-slit mode to obtain a high-quality integrated light spectrum by scanning a selected region within Leo A, for which a CMD reaching the old main sequence turn-off (oMSTO) is available from HST. We compared the SFH obtained from the two datasets, using state-of-art methods of integrated light (STECKMAP) and resolved stellar population analysis. In the case of the CMD, we computed the SFH both from a deep CMD (observed with HST/ACS) and from a shallower CMD (archival data from HST/WFPC2). Results. The agreement between the SFHs recovered from the oMSTO CMD and from full spectrum fitting is remarkable, particularly regarding the time evolution of the star formation rate. The overall extremely low metallicity of Leo A is recovered up to the last 2 Gyrs when some discrepancies appear. A relatively high metallicity found for the youngest stars from the integrated data is a recurring feature that might indicate that the current models or synthesis codes should be revised, but that can be significantly mitigated using a more restrictive metallicity range. We thoroughly inspect the robustness of both approaches separately, finding that the subtle differences between them are inherent to the methods themselves. The SFH recovered from the shallow CMD also presents differences with the other two. Conclusions. Modern full-spectral fitting codes are able to recover both average constant SFHs (LMC case) and SFHs with a dominant fraction of young stellar populations. The analysis of high S/N spectra seems to provide more reliable SFH estimates than that of CMDs not reaching the oMSTO. The comparison presented in this paper needs to be repeated for predominantly old systems, thus assessing the performance of full-spectrum fitting for a full range of SFHs.

LBT/LUCI SPECTROSCOPIC OBSERVATIONS OFz≃7 Galaxies GALAXIES

We present deep near-infrared spectroscopic observations of 13 luminous Lyman break galaxies (LBGs) () and a lensed LBG candidate, MACS1149-JD1, using the LBT/LUCI spectrograph in the multi-object mode and long-slit mode, respectively. The galaxies are selected in one of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/WIDE survey observations, the UKIRT Infrared Deep Sky Survey Ultra Deep Survey field, and MACS1159-JD1 is selected from the Cluster Lensing And Supernova survey with Hubble survey observations. With ∼4–5 hr integrations, the LBT spectra are sensitive to Lyα emission, with rest-frame equivalent width greater than 55 A ( A) at and 90 A ( A) at . No Lyα emission is observed in any of the LBGs. After correcting the spectroscopic incompleteness, our measurements place an upper limit on the Lyα emission fraction of in luminous LBGs at . This result is consistent with the lack of Lyα emission in LBGs in previous studies. Together with other measurements of the Lyα emission fraction in LBGs at , this study puts a strong constraint on the fraction of luminous LBGs with large EW Lyα, . We estimate the expected Lyα emission fraction at by extrapolating the evolution of the fraction at low redshifts and find that the observed Lyα emission fraction is lower than the expected Lyα emission fraction at the 89% significance level, consistent with expectations if Lyα emission in LBGs has been suppressed by neutral hydrogen in the intergalactic medium or optically thick absorbers around the galaxies. We do not find any strong Lyα emission feature at the redshift range of 7.3–9.7 in the MACSJ1159-JD1 spectrum, either. This is consistent with the conclusion that Lyα emission in the galaxy has been highly suppressed.

Near-infrared spectroscopy in NGC 7538

The characterisation of the stellar population toward young high-mass star-forming regions allows to constrain fundamental cluster properties like distance and age. These are essential when using high-mass clusters as probes to conduct Galactic studies. NGC 7538 is a star-forming region with an embedded stellar population only unearthed in the near-infrared. We present the first near-infrared spectro-photometric study of the candidate high-mass stellar content in NGC 7538. We obtained H and K spectra of 21 sources with both the multi-object and long-slit modes of LIRIS at the WHT, and complement these data with sub-arcsecond JHKs photometry of the region using the imaging mode of the same instrument. We find a wide variety of objects within the studied stellar population of NGC 7538. Our results discriminate between a stellar population associated to the HII region, but not contained within its extent, and several pockets of more recent star formation. We report the detection of CO bandhead emission toward several sources as well as other features indicative of a young stellar nature. We infer a spectro-photometric distance of 2.7+-0.5 kpc, an age spread in the range 0.5-2.2 Myr and a total mass ~1.7x10^3 Msun for the older population.

SpS1-Silicate dust formation around AGB stars

VISIR, the VLT Imager and Spectrograph for the Mid-Infrared is a multi-mode instrument, featuring also a high resolution Echelle spectrograph with a spectral resolving power $\frac{\nu}{\Delta \nu}$ of ≈30 000 or 10 km s−1 at ν ≈ 30 000 GHz (λ ≈ 10 μm). A limited long-slit mode as well as a general cross-dispersed mode are available. The Echelle grating is illuminated with a 200 mm diameter collimated beam. Cross-dispersion is achieved by a pair of grisms in the pre-slit optics. The entire frequency interval corresponding to the “10 μ m-window” from 22 400 to 39 500 GHz is fully accessible, albeit sequentially. This interval contains a multitude of fundamental molecular rotational-vibrational bands such as SiO, OH−, H2O, NH3, CH4 and many other hydro-carbonates. Since its commissioning in April 2004, VISIR has been plagued by artifacts introduced from its detector. The cross-dispersed mode is especially handicapped, as it is the most demanding mode for dynamic range of illumination. Now an ambitious upgrade with a pair of newly developed 1k2 As:Si detectors is underway, which will fully resurrect the spectroscopic mode. This will also increase the frequency interval accessible in one exposure by 240% while changing from critical to 3-pixel sampling. Even in the absence of extra spectral features this increase is quite valuable for absorption line spectroscopy, as the limiting factor in analysis often is the definition of the photospheric continuum.

A Search for Temperature and Density Variations in NGC 7027 with theHubble Space Telescope

We observed the young planetary nebula NGC 7027 with the HST Imaging Spectrograph (STIS) in long-slit mode at five slit positions along the major axis of the nebula, over the wavelength range from 3000 to ~10,000 A. We used dereddened line ratios to determine line-of-sight average values for (1) He^(++) and He^+ ionization fractions from He II λ4686 and He I λ5876; (2) electron density from both [S II] (λ6716/λ6731) and [Ar IV] (λ4711/λ4740); and (3) temperature from [O III] (λ4959 + λ5007)/λ4363. The He^(++)/H^+ ratio varies across the nebula, with values up to 0.06 over the central parts, falling off to 0.03 at offsets of 5-6 from the central star. The line-of-sight mean densities vary by factors of ~5 on angular scales as small as ~1. The average electron temperatures are generally consistent with a constant = 13,800 ± 2000 K within the uncertainties, except for ~2% of measured pixels where T_e > 18,000 K. The variations of density along the slits are not obviously correlated with variations in extinction. The ionization structure of the nebula varies on both large and small scales. [O I] λ6300, Hα, and He II λ4686 intensity profiles along each slit appear to trace ionization gradients at Hα peaks, with the highest ionization on the side toward the central star and lowest ionization on the far side. These structures may result from effects of stellar radiation, shocks from a fast stellar wind, or some combination of the two processes.

NGC 5011C: An Overlooked Dwarf Galaxy in the Centaurus A Group

A critical study of the properties of groups of galaxies can be done only once a complete census of group members is available. Despite extensive surveys, even nearby groups can lead to surprises. Indeed, we report the discovery of a previously unnoticed member of the Centaurus A Group, NGC 5011C. While the galaxy is a well-known stellar system listed with a NGC number, its true identity has remained hidden because of coordinate confusion and wrong redshifts in the literature. NGC 5011C attracted our attention since, at a putative distance of 45.3 Mpc, it would be a peculiar object with a very low surface brightness typical of a dwarf galaxy and, at the same time, a size typical of an early-type spiral or S0 galaxy. To confirm or reject this peculiarity, our immediate objective was to have the first reliable measurement of its recession velocity. The observations were carried out with EFOSC2 at the 3.6 m European Southern Observatory (ESO) telescope, and the spectra were obtained with the instrument in long-slit mode. The redshifts of both NGC 5011C and its neighbor NGC 5011B were computed by cross-correlating their spectra with that of a radial velocity standard star. We found that NGC 5011C indeed has a low redshift of v⊙ = 647 ± 96 km s-1 and thus is a nearby dwarf galaxy rather than a member of the distant Centaurus cluster, as believed for the past 23 years. Rough distance estimates based on photometric parameters also favor this scenario. As a by-product of our study we update the redshift for NGC 5011B to v⊙ = 3227 ± 50 km s-1. Applying population synthesis techniques, we find that NGC 5011B has a luminosity-weighted age of 4 ± 1 Gyr and a solar metallicity, and that the luminosity-weighted age and metallicity of NGC 5011C are 0.9 ± 0.1 Gyr and 1/5 solar. Finally, we estimate a stellar mass of NGC 5011C comparable to that of dwarf spheroidal galaxies in the Local Group.

11.6. Spectral monitoring of AGN at the 6 meter telescope

To study broad line region (BLR) size and kinematics spectral monitoring of NGC 3516, NGC 4151, NGC 5548, NGC 7469 and 3C390.3 has been performed with the 6 m telescope of the Special Astrophysical Observatory (N. Arkhyz- North Caucasus) in 1986–1996. The spectra are obtained in the Nasmyth focus using the TV scanner with a resolution of 3–4Å and S/N= 10–25 within 4000–5200ÅÅ (1986–94, 500 spectra), and in the prime focus with the spectrograph UAGS (a long-slit mode) + CCD (resolution 5–10Å) or multi-pupil field spectrograph (MPFS) + CCD (resolution 4Å) within 4000–7000ÅÅ and S/N=50–100 (1995–96, 270 spectra).

Optical Identifications for a Sample of REXs: Search for BL Lac Objects

Twenty six Radio Emitting X-ray Sources (REXs) have been observed in two observing runs as part of a project aimed at selecting a new and large sample of BL Lac objects (see Wolter et al. this conference). Sources were selected by cross-correlating ROSAT-PSPC public images against VLA radio surveys. Here we present results from the first observations of 14 sources conducted in April 1995 with a B&C spectrograph in longslit mode using a CCD-Tektronix TK-1024 AB detector at the 2.1m San Pedro Martir telescope (Mexico). Table 1 shows the data derived for the 8 confirmed REXs. X-ray fluxes are in units of erg cm–2 sec–1 in the 0.1-2.4 keV band, radio fluxes are in mJy at 5 GHz, X-ray luminosities are in erg sec–1 in the energy range 0.1-2.4 keV and radio luminosities are in erg sec–1 at 5 GHz. We assumed Ho = 50 km sec–1 Mpc–1 and qo = 0. A more detailed description of individual sources will be published elsewhere.

S0 Galaxy Line Strengths and Gradients

Line strengths and their gradients in Mg, Fe, and Hβ have been determined for a sample of 20 S0 galaxies in order to study the stellar populations of their bulges and disks and to investigate their relationship to elliptical galaxies. The data were obtained with the Lick Observatory 3m telescope in the long-slit mode over the region 4215–5615 Å with resolution 3.1 Å.

Field Spectroscopy by Optical Fibres: development of the ”ALBIREO” spectrograph

AbstractA multi-function spectrograph has been built for the new 1.52 m telescope in the Sierra Nevada Observatory near Granada (Spain). It uses optical fibres for both multi-object spectroscopy and integral field spectroscopy, in addition to classical imaging and long-slit modes.

The giant branch of Omega Centauri. III - C, N, O and heavy-element abundances for 15 red giants

view Abstract Citations (76) References (77) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Giant Branch of Omega Centauri. III. C, N, O and Heavy-Element Abundances for 15 Red Giants Paltoglou, G. ; Norris, John E. Abstract Observations of 15 red giants in the Galactic globular cluster Omega Cen are reported. Photometry in the V band and at 1.05 microns and 421.5 nm was obtained using the 0.6-m and 2.3-m telescopes at Siding Spring Mountain; spectra were obtained at 421-433, 611-627, and 626-642 nm using the RGO spectrograph in long-slit mode on the AAT; the results are combined with published data in extensive tables and graphs and characterized in detail. Findings discussed include Fe abundances ranging over 0.6 dex, evidence for surface mixing of CN-cycle and ON-cycle material, a positive correlation between Na/Fe and N/Fe abundance ratios, Si and Ca overabundant relative to O and Fe, and a general overabundance of s-process elements. Publication: The Astrophysical Journal Pub Date: January 1989 DOI: 10.1086/167005 Bibcode: 1989ApJ...336..185P Keywords: Globular Clusters; Heavy Elements; Milky Way Galaxy; Red Giant Stars; Stellar Spectra; Abundance; High Resolution; Peculiar Stars; Variable Stars; Astrophysics; CLUSTERS: GLOBULAR; NUCLEOSYNTHESIS; STARS: ABUNDANCES; STARS: LATE-TYPE full text sources ADS | data products SIMBAD (20) Related Materials (5) Part 1: 1976ApJ...208..369B Part 2: 1976ApJ...210..618B Part 3: 1977ApJ...211L..91N Part 5: 1995ApJ...447..680N Part 6: 1996ApJ...462..241N

SMALL-SCALE KINEMATIC STRUCTURES IN RING NEBULAE AROUND WOLF-RAYET STARS

ABSTRACT Four ring nebulas around galactic Wolf-Rayet stars have been observed with echelle spectrographs in the long-slit mode: NGC 2359, NGC 3199, NGC 6888, and RCW 58. The spatial resolution of these observations is seeing limited at about 1-3 arcsec, which is almost a two orders of magnitude improvement from the previous Fabry-Perot scanner observations. To avoid large geometric corrections, the slit positions were placed as close to the central stars as possible. The results show that the ejecta-type nebula RCW 58 is a clumpy shell expanding regularly at about 110 km/s, as opposed to the chaotic expansion concluded from the earlier Fabry-Perot observations. For the three windblown bubbles, NGC 2359, NGC 3199, and NGC 6888, the small-scale structures revealed in the echelle data can explain the apparently discrepant expansion velocities derived from the previous large-aperture Fabry-Perot observations.