scholarly journals 7.3. Sgr A∗ in the mid-infrared reference frame: no evidence of an infrared counterpart, or interaction with nearby sources

1998 ◽  
Vol 184 ◽  
pp. 295-297
Author(s):  
Dan Gezari
Keyword(s):  
Near Infrared ◽  
Reference Frames ◽  
A Priori ◽  
Infrared Emission ◽  
Mid Infrared ◽  
Source Component ◽  
Comparable Accuracy ◽  
Sgr A ◽  
Central Parsec ◽  
Infrared Sources

We have determined the position of Sgr A∗ with respect to the mid-infrared (5-25 m) sources in the central parsec by direct correlation of our 12.4 m array image (Gezari et al. 1994) and the new 2-cm continuum VLA map (Yusef-Zadeh 1997; private communication), without a priori knowledge of any other position determinations. Menten et al. (1997) recently succeeded in registering the radio and near-infrared (2.2 m) reference frames with high precision (+0.03 arcsec) using VLA observations of Sgr A∗, SiO masers and H2O masers. Unfortunately, registering the mid-infrared and radio reference frames with comparable accuracy cannot be done by applying the 2.2 m calibration. Most near-infrared sources have no detectable mid-infrared counterparts, and it is not obvious which of those that do are coincident (if any), since near-infrared and mid-infrared emission generally does not arise from the same physical source component. Dramatic examples of shifts between the brightest near- and mid-infrared peaks can be seen in Orion BN/KL and the Ney-Allen Nebula (Gezari and Backman 1994; Gezari, Backman and Werner 1997) corresponding to 0.1 - 0.5 arcsec if they were located at 8.5 kpc. Further, several Sgr A West IRS sources are displaced significantly in the infrared and radio, suggesting they may actually be compact clusters of objects.

scholarly journals Mid-Infrared (4.8–12.4 and 20.0 μm) Imaging of the Galactic Center: Modeling the Dust Emission and Energetics of the Central Parsec

1996 ◽  
Vol 169 ◽  
pp. 231-240 ◽  
Author(s):  
Dan Gezari ◽  
Eli Dwek ◽  
Frank Varosi
Keyword(s):  
Galactic Center ◽  
Dust Emission ◽  
Infrared Emission ◽  
Mid Infrared ◽  
New Model ◽  
Central Engine ◽  
Direct Indication ◽  
Sgr A ◽  
Central Parsec ◽  
Array Camera

We have modeled the mid-infrared emission from the Galactic Center using our array camera images at eight wavelengths. The results suggest that the high infrared luminosity of the region is provided by a cluster of luminous stars. There is no direct indication in the new model results of a very luminous object or “central engine” near Sgr A∗.

scholarly journals Diffraction Limited Near Infrared Imaging of the Central Parsec of the Galaxy

1994 ◽  
Vol 158 ◽  
pp. 379-381
Author(s):  
A. Eckart ◽  
R. Genzel ◽  
R. Hofmann ◽  
B.J. Sams ◽  
L.E. Tacconi-Garman
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Core Radius ◽  
The Galaxy ◽  
K 13 ◽  
Sgr A ◽  
Central Parsec ◽  
Stellar Sources ◽  
Stellar Density ◽  
Source Number

We present deep 1.6 and 2.2 μm images of the central parsec of the Galaxy at a resolution of 0.15″. Most of the flux in earlier seeing limited images comes from about 340 unresolved stellar sources with K≤14. The IRS 16 and 13 complexes are resolved into about two dozen and half a dozen sources, a number of which are probably luminous hot stars. We confirm the presence of a blue near infrared object (K≈13) at the position of the compact radio source Sgr A∗. The spatial centroid of the source number distribution is consistent with the position of Sgr A∗ but not with a position in the IRS 16 complex. The stellar surface density in the central 10″ is very well fitted by an isothermal cluster model with a well defined core radius. The derived core radius of all 340 sources is 0.15±0.05 pc. The central stellar density is a few times 107 M⊙ pc−3. Buildup of massive stars by merging of lower mass stars and collisional disruption of giant atmospheres are very probable processes in the central 0.2 pc.

TUNABLE MID-INFRARED SOURCES USING SECOND-ORDER NONLINEARITIES

1992 ◽  
Vol 01 (03) ◽  
pp. 639-672 ◽  
Author(s):  
NORMAN P. BARNES
Keyword(s):  
Solid State ◽  
Near Infrared ◽  
High Efficiency ◽  
Nonlinear Crystal ◽  
Second Order ◽  
Solid State Lasers ◽  
Mid Infrared ◽  
Crystal Properties ◽  
Efficiency Performance ◽  
Infrared Sources

Tunable mid-infrared sources can be created using crystals having second-order non-linearities and solid-state lasers operating in the near infrared. Such devices have already demonstrated large tuning ranges and high efficiency. Performance of these devices as well as their potential for higher output energies and narrow spectral bandwidth operation are analyzed in terms of nonlinear crystal properties and solid-state laser requirements.

scholarly journals SiO and H2O Masers in the Central Parsec of the Galaxy

1998 ◽  
Vol 164 ◽  
pp. 229-230 ◽  
Author(s):  
Karl M. Menten ◽  
Mark J. Reid
Keyword(s):  
Galactic Center ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Proper Motions ◽  
Infrared Images ◽  
Evolved Stars ◽  
The Galaxy ◽  
Sgr A ◽  
Central Parsec ◽  
Infrared Sources

AbstractWe have discovered maser emission from SiO and H2O molecules toward a number of evolved stars within the central parsec of our Galaxy. The maser positions can be registered with milliarcsecond precision relative to the radio continuum emission of the nonthermal Galactic center source Sgr A*. Since the masing stars are prominent infrared sources, our data can be used to locate the position of Sgr A* on infrared images of the Galactic center region. Using VLBA observations it will be possible to measure proper motions of the maser stars, which can be used to put constraints on the mass distribution in the central parsec.

scholarly journals 7.4. The 3.4 micron absorption in the Galactic center sources

1998 ◽  
Vol 184 ◽  
pp. 299-300
Author(s):  
T. Nagata
Keyword(s):  
Interstellar Medium ◽  
Near Infrared ◽  
Galactic Center ◽  
Absorption Feature ◽  
Visual Extinction ◽  
Stretching Vibrations ◽  
Central Parsec ◽  
Infrared Sources

The 3.4μm absorption feature, first detected in the Galactic center source IRS7 (Soifer et al., 1976), has been observed in other Galactic center sources IRS3, IRS12 (McFadzean et al., 1989), and IRS6E (Pendleton et al., 1994). This feature is regarded as characteristic of dust in the diffuse interstellar medium, and attributed to C-H stretching vibrations. Several objects in the lines of sight other than the Galactic center is now known to have the feature (Sandford et al. 1995 and references therein; Imanishi et al. 1996). The absorption depths per unit visual extinction τ3.4/AV for these sources are compared with those for the Galactic center sources, and they are thought to increase near the Galactic center. However, the “Galactic center” sources are all in the central parsec cluster, and the features observed in them may be only representative of interstellar medium local to the central parsec, not the general diffuse interstellar medium of the inner Galaxy. In this paper, we report the 3.4μm absorption feature detected in near-infrared sources within 1° of the Galactic center.

scholarly journals The Carnegie Supernova Project II

2020 ◽  
Vol 639 ◽  
pp. A103 ◽  
Author(s):  
M. D. Stritzinger ◽  
F. Taddia ◽  
M. Fraser ◽  
T. M. Tauris ◽  
N. B. Suntzeff ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Electron Capture ◽  
Near Infrared ◽  
Companion Paper ◽  
Infrared Emission ◽  
Light Curves ◽  
Data Set ◽  
Mid Infrared ◽  
Space Telescope ◽  
Infrared Wavelength

We present multiwavelength observations of two gap transients that were followed by the Carnegie Supernova Project-II. The observations are supplemented with data obtained by a number of different programs. Here in the first of two papers, we focus on the intermediate-luminosity red transient (ILRT) designated SNhunt120, while in a companion paper we examine the luminous red novae AT 2014ej. Our data set for SNhunt120 consists of an early optical discovery, estimated to be within three days after outburst, the subsequent optical and near-infrared broadband followup extending over a period of about two months, two visual and two near-infrared wavelength spectra, and Spitzer Space Telescope observations extending from early (+28 d) to late (+1155 d) phases. SNhunt120 resembles other ILRTs such as NGC 300-2008-OT and SN 2008S, and like these other ILRTs, SNhunt120 exhibits prevalent mid-infrared emission at both early and late phases. From the comparison of SNhunt120 and other ILRTs to electron-capture supernova simulations, we find that the current models underestimate the explosion kinetic energy and thereby produce synthetic light curves that overestimate the luminosity. Finally, examination of pre-outburst Hubble Space Telescope images yields no progenitor detection.

scholarly journals The Luminosity of the Central Parsec of the Galaxy

1989 ◽  
Vol 136 ◽  
pp. 423-436
Author(s):  
M. W. Werner ◽  
J. A. Davidson
Keyword(s):  
Near Infrared ◽  
Galactic Center ◽  
Thermal Emission ◽  
Large Magellanic Cloud ◽  
Infrared Emission ◽  
Infrared Observations ◽  
The Galaxy ◽  
Infrared Wavelengths ◽  
Central Parsec ◽  
30 Doradus

The luminosity of the central 5 pc of the Galaxy -encompassing the inner regions of the rotating ring of dust and gas which surrounds the galactic center - emerges primarily at infrared wavelengths in the form of thermal emission from heated dust. The nature and location of the sources which heat the dust can be inferred from the spatial and temperature distribution of the thermal infrared emission (λ>20um), from studies of the ionized gas in this region, and from direct imaging in the near infrared. These observations show that the principal heating sources within this 5-pc region are concentrated within the central parsec of the Galaxy and indicate that the luminosity of these sources is within a factor of two of 107 LO. The near-infrared observations of the compact sources at the galactic center do not reveal a single dominant source but suggest instead that the several components of the IRS-16 complex, taken together, may contribute the bulk of the luminosity; however, the data also permit a single object to dominate the energetics of this region. We draw attention to the striking morphological similarities between the galactic center and the innermost regions of the 30 Doradus nebula in the Large Magellanic Cloud and speculate that the luminosity sources in the galactic center may resemble the early-type supergiants in 30 Doradus.

scholarly journals The Diffuse Near- and Mid-Infrared Emission from the Galaxy

2001 ◽  
Vol 204 ◽  
pp. 35-46
Author(s):  
Martin Cohen
Keyword(s):  
Point Source ◽  
Surface Brightness ◽  
Near Infrared ◽  
Infrared Emission ◽  
Point Sources ◽  
Mid Infrared ◽  
Deep Point ◽  
Model Predictions ◽  
The Galaxy ◽  
Fundamental Stellar Parameters

Recognition of an isotropic cosmic near-infrared (NIR) and mid-infrared (MIR) background involves the removal of the zodiacal foreground (both scattered and reradiated), of the truly diffuse Galactic foreground (dominated by fluorescent bands of polcyclic aromatic hydrocarbons), and of resolved and unresolved Galactic point sources. I discuss model simulations of the near- and mid-infrared point source sky from which one can assess its particular contribution to the diffuse Galactic infrared foreground. I will also indicate the transitional stage which characterizes our knowledge of fundamental stellar parameters that are essential inputs to any such models. Using the latest version of the SKY model (Wainscoat et al. 1992; Cohen 1993; Cohen 1994; Cohen et al. 1994; Cohen 1995; Ruphy et al. 1997), I will demonstrate matches to deep point source counts for a variety of passbands and galactic latitudes, and will try to quantify the uncertainties achievable in model predictions of the integrated surface brightness due to the smearing of all these foreground point sources.

scholarly journals Near-Infrared Sources in the Complex H II Region NGC 6357

1987 ◽  
Vol 115 ◽  
pp. 187-188
Author(s):  
P. Persi ◽  
M. Ferrari-Toniolo ◽  
M. Roth ◽  
M. Tapia
Keyword(s):  
Near Infrared ◽  
Baja California ◽  
Infrared Emission ◽  
Radio Continuum ◽  
Star Forming ◽  
H Ii Region ◽  
Infrared Sources ◽  
Near Infrared Emission ◽  
Water Maser

We have searched for the near-infrared emission from selected areas of the star forming region NGC 6357. Six fields of 90x90 arcsec2 centered on the far-IR peaks G353.19+0.91, G353.22+0.67, G353.13+0.64, G353.05+0.56, on the 6-cm radio continuum peak G353.035+0.78, and on the water maser source H20353.27+0.64, were scanned through the K(2.2 μm) filter at the 2.1-m telescope of the Observatorio Astronómico Nacional at S. Pedro Mártir, Baja California, México.

scholarly journals Infrared observations of GGD objects

1987 ◽  
Vol 122 ◽  
pp. 125-126
Author(s):  
R. Carballo ◽  
C. Eiroa ◽  
A. Mampaso
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Far Infrared ◽  
Infrared Emission ◽  
Be Stars ◽  
Main Sequence Stars ◽  
Infrared Excess ◽  
Dark Clouds ◽  
Infrared Sources ◽  
Different Characteristics

We present accurate positions and near infrared photometry (Table I) of 11 point-like objects in the neighbourhood of GGD objects obtained on the 1.55 m and on the 1.23 m in Teide Obs. and Calar Alto Obs. respectively, in Spain. Several of the near infrared sources are directly associated with the GGD nebulae and/or are candidate for their excitation. In addition some of them seem to be the near infrared counterparts of IRAS sources. We believe, on the basis of their infrared excess, far infrared emission (IRAS), association with nebulosity, coincidence with H2O masers or the fact that in most cases the observed luminosities are higher than those expected for main sequence stars, that most of them (9/12) are young stars embedded in the dark clouds which contain the GGD objects. The loci of the detected sources in an (H-K,K-L) infrared two-colour diagram is the same as that obtained for known pre-main sequence stars, such as T Tauris and Herbig Ae-Be stars, indicating the presence of dust shells with temperatures in the range 800–1500 K. The observed range in luminosity, 10–4600 L⊙, added to other different characteristics found between them, such' as the presence, or absence, of H2O masers, indicates the interest for a detailed study of the infrared sources and related GGD nebulae.

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