- ID:
- ivo://CDS.VizieR/J/ApJ/453/616
- Title:
- JHKL photometry of 12 micron galaxy sample
- Short Name:
- J/ApJ/453/616
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aperture photometry from our own observations and the literature is presented for the 12 um galaxies in the near-infrared J, H, and K bands and, in some cases, in the L band. These data are corrected to "total" near-infrared magnitudes (with a typical uncertainty of 0.3mag) for a direct comparison with our IRAS fluxes which apply to the entire galaxy. The corrected data are used to derive integrated total near-infrared and far-infrared luminosities. We then combine these with blue photometry and an estimate of the flux contribution from cold dust at wavelengths longward of 100um to derive the first bolometric luminosities for a large sample of galaxies. The presence of nonstellar radiation at 2-3um correlates very well with nonstellar IRAS colors. This enables us to identify a universal Seyfert nuclear continuum from near- to far-infrared wavelengths. Thus, there is a sequence of infrared colors which runs from a pure "normal galaxy" to a pure Seyfert/quasar nucleus. Seyfert 2 galaxies fall close to this same sequence, although only a few extreme narrow-line Seyfert galaxies have quasar-like colors, and these show strong evidence of harboring an obscured broad-line region. A corollary is that the host galaxies of Seyfert nuclei have normal near- to far-infrared spectra on average. Starburst galaxies lie significantly off the sequence, having a relative excess of 60um emission probably as a result of stochastically heated dust grains. We use these correlations to identify several combinations of infrared colors which discriminate between Seyfert 1 and 2 galaxies, LINERs, and ultraluminous starbursts. In the infrared, Seyfert 2 galaxies are much more like Seyfert 1s than they are like starbursts, presumably because both kinds of Seyferts are heated by a single central source, rather than a distributed region of star formation. Moreover, combining the [25-2.2um] color with the [60-12um] color, it appears that Seyfert 1 galaxies are segregated from Seyfert 2 galaxies and starburst galaxies in a well-defined region characterized by the hottest colors, corresponding to the flattest spectral slopes. Virtually no Seyfert 2 galaxy is present in such a region. To reconcile this with the "unified scheme" for Seyfert 1 and 2 galaxies would therefore require that the higher frequency radiation from the nuclei of Seyfert 2 galaxies to be absorbed by intervening dust and re-emitted at lower frequencies. We find that bolometric luminosity is most closely proportional to 12um luminosity. The 60 and 25um luminosities rise faster than linearly with bolometric luminosity, while the optical flux rises less than linearly with bolometric luminosity. This result is a confirmation of the observation that more luminous disk galaxies have relatively more dust-enshrouded stars. Increases in the dust content shifts luminosity from the optical to 25-60um, while leaving a "pivot point" in the mid-IR essentially unchanged. Thus, 12um selection is the closest available approximation to selection by a limiting bolometric flux, which is approximately 14 times nu.L_nu at 12um for non-Seyfert galaxies. It follows that future deep surveys in the mid-infrared, at wavelengths of 8-12um, will simultaneously provide complete samples to different bolometric flux levels of normal and active galaxies, which will not suffer the strong selection effects present both in the optical-UV and far-infrared.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/463/703
- Title:
- JHKL photometry of MWC 560
- Short Name:
- J/A+A/463/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- MWC 560 (V694 Mon) is one of the most enigmatic symbiotic system with a very active accretion-powered hot component. Such activity can be supported only by a luminous asymptotic giant branch star, i.e. a Mira or SR variable, with a high mass-loss rate. It is also a very unusual jet source because the jet axis lies practically parallel to the line of sight. The aims of our study are the determination of the evolutionary status of the cool component of MWC 560. Our methods involve analysis of near-IR JHKL and optical light curves. The cool component of MWC 560 pulsates with a period of ~340 days, and it is probably a red SR variable on the thermally pulsing AGB. The high mass-loss rate expected for such a star is sufficient to power the observed activity of the hot companion.
- ID:
- ivo://CDS.VizieR/J/A+A/450/253
- Title:
- JHKL photometry of RCW57/NGC3576
- Short Name:
- J/A+A/450/253
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- L-band data of RCW 57 at 3.5 micron taken with SPIREX (South Pole Infrared Explorer) is presented. The photometry was combined with 2MASS JHK data at 1.25 -2.2 micron. Colour-colour and colour-magnitude diagrams are constructed and used to determine the sources with infrared excess. These are interpreted as circumstellar disks, and enable the fraction of sources with disks (the cluster disk fraction or CDF) to be determined. We find that more than 50% of the sources detected at L-band in RCW 57 have an IR-excess.
- ID:
- ivo://CDS.VizieR/J/A+A/458/533
- Title:
- JHKL' photometry of selected AGB stars
- Short Name:
- J/A+A/458/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared monitoring programme of a selected sample of stars, initially suspected to be Mira variables and OH/IR stars, covering more than a decade of observations. The objects monitored cover the typical range of IRAS colours shown by O-rich stars on the asymptotic giant branch and show a surprisingly large diversity of variability properties. Sixteen objects are confirmed as large-amplitude variables.
- ID:
- ivo://CDS.VizieR/J/ApJ/470/864
- Title:
- JHKL photometry of the Galactic Center
- Short Name:
- J/ApJ/470/864
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- J, H, K, and L photometry for the stars in the central ~2' (~5pc) of the Galaxy are presented. Using the observed J-H, H-K, and K-L colors and assumed intrinsic colors, we determine the interstellar extinction at 2.2mm (A_K_) for approximately 1100 individual stars. The mean A_K_ (=3.3mag) is similar to previous results, but we find that the reddening is highly variable, and some stars are likely to be seen through A_K_>6mag. The dereddened K-band luminosity function points to a significantly brighter component to the stellar population (>1.5mag at K) than found in the stellar population in Baade's window, confirming previous work done at lower spatial resolution. The observed flux of all Galactic center stars with estimated K0 (dereddened magnitude) =<7.0mag is ~25% of the total in the 2'x2' field. The data were obtained in July 11-13 on the 4m telescope at the Cerro Tololo Observatory (CTIO) using the Ohio State Infrared Imager qnd Spectrometer (OSIRIS). Our observations confirm the recent finding that several bright M stars in the Galactic center are variable. Our photometry also establishes the near-infrared variability of the M1-2 supergiant, IRS 7.
- ID:
- ivo://CDS.VizieR/J/ApJ/353/494
- Title:
- JHKL photometry on Galactic bulge M Giants
- Short Name:
- J/ApJ/353/494
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- JHKL colors and CO and H2O indices are presented for an unbiased sample of about 250 M giants drawn from complete surveys for such stars along the minor axis of the Galaxy at latitudes between -3deg and -12deg. Magnitudes at 10 {mu}m and narrow-band near-infrared colors for some of these stars are also given. At constant J-K the mean CO index of the bulge M giants weakens monotonically with increasing latitude. From the relation between CO and [Fe/H] established for star clusters, this would correspond to a decrease of ~0.4 dex in the mean [Fe/H] between the -3deg and -12deg fields, from somewhat greater to somewhat less than solar. These values are consistent with abundances derived from optical color-magnitude diagrams. Despite these high [Fe/H] values, the ridgelines of the color-magnitude diagrams for all fields lie between those of 47 Tucanae and M3. There is a mild blueward shift with increasing latitude seen in the integrated mean J-K colors of the fields. A steady progression with latitude in the mean (J-H, H-K) relation for the bulge M giants is observed. For the -12deg field it is significantly displaced from the one for local field giants and overlaps that for globular cluster stars; for the -3deg field it is displaced by about the same amount, but on the opposite side of the field giant relation. Dispersions about this relation and the mean (CO, J-K) relation for the M giants in each field are comparable in size to the measuring uncertainties alone, but in a given field the displacements of individual stars from these two mean relations are statistically correlated. We attribute this correlation to a spread in metallicity within each field but note that this spread is smaller than the total metallicity range over all fields. In addition, metallicity-related effects result in J-H getting bluer with increasing metallicity in stars of similar temperature. The bolometric luminosity function of the nonvariable M giants is nearly independent of latitude. All show a sharp cutoff at Mbol<=-4.2; such a cutoff could be a good extragalactic distance indicator for bulgelike stellar populations. The reddest (J-K>=-1.35) and most luminous stars are found only in the low-latitude windows; all are M7-M9 giants, long-period variables (LPVs), or both. Except for these reddest stars, the ratio at a given color of M7-M9 giants to earlier type giants is independent of latitude. Only when stars of all colors in a spectral group are considered is the rapid falloff seen in the ratio of M7-M9 giants respect to earlier types. The bulge LPVs have <Mbol> = -4.2. Since this is nearly the same as for LPVs in globular clusters, it does not require an age for the bulge population significantly younger than that of globular clusters. Their spatial distribution is similar to that of the reddest late M giants. The LPVs with the reddest colors, attributed to the most extensive circumstellar dust shells, are found in the lowest latitude fields. Most of the bulge IRAS sources in the fields studied can be identified with these LPVs or with the brightest nonvariable M giants; many of the latter are probably foreground objects. The reddest IRAS sources are at the lowest latitudes and have the coolest [12-25]{mu}m colors. The bulge IRAS sources do not appear to represent a different or more luminous class of objects than the optically identified M giants. Five different estimators of the surface brightness and surface density between latitudes -3deg and -12deg have a power-law dependence on radius with exponent between -2.5 and -3.4. The value of the exponent depends on the metallicity of the estimator: the most metal-rich objects have the steepest falloff. However, even the smallest exponent, which characterizes the total light and mass distribution, places the bulge among the most spatially concentrated of those measured by Kent for a sample of 22 Sb-Sc galaxies. Thus the mass distribution within the inner 1.5 kpc of the Galaxy is quite sharply peaked.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1993
- Title:
- JHK magnitudes of Sculptor dSph RR Lyrae
- Short Name:
- J/AJ/135/1993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained single-phase near-infrared magnitudes in the J and K bands for a sample of 78 RR Lyrae stars in the Sculptor dSph galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/160/115
- Title:
- JHK observation of 75 OB stars in Cyg OB2
- Short Name:
- J/AJ/160/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Near-Infrared Imager camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early-B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions. The observations are sensitive to equal-brightness pairs at separations as small as 0.08", and progressively fainter companions are detectable out to {Delta}K=9mag at a separation of 2". This faint contrast limit due to read noise continues out to 10" near the edge of the detector. We assigned a simple probability of chance alignment to each companion based upon its separation and magnitude difference from the central target star and upon areal star counts for the general star field of Cyg OB2. Companion stars with a field membership probability of less than 1% are assumed to be physical companions. This assessment indicates that 47% of the targets have at least one resolved companion that is probably gravitationally bound. Including known spectroscopic binaries, our sample includes 27 binary, 12 triple, and 9 systems with 4 or more components. These results confirm studies of high-mass stars in other environments that find that massive stars are born with a high-multiplicity fraction. The results are important for the placement of the stars in the Hertzsprung-Russell diagram, the interpretation of their spectroscopic analyses, and for future mass determinations through measurement of orbital motion.
- ID:
- ivo://CDS.VizieR/J/AJ/127/3553
- Title:
- JHK photometry and spectroscopy for L and T dwarfs
- Short Name:
- J/AJ/127/3553
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new JHK photometry on the MKO-NIR (Mauna Kea Observatories Near-Infrared) system and JHK spectroscopy for a large sample of L and T dwarfs. Photometry has been obtained for 71 dwarfs, and spectroscopy for 56. The sample comprises newly identified very red objects from the Sloan Digital Sky Survey (SDSS, http://www.sdss.org/) and known dwarfs from the SDSS and the Two Micron All Sky Survey (2MASS, Cat. <II/246>). Spectral classification has been carried out using four previously defined indices from Geballe et al. (2002ApJ...564..466G) that measure the strengths of the near infrared water and methane bands.
- ID:
- ivo://CDS.VizieR/J/A+A/461/949
- Title:
- JHK photometry around IRAS 09149-4743
- Short Name:
- J/A+A/461/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a near-infrared survey of the young stellar cluster associated with IRAS 09149-4743, a member of the Vela Molecular Ridge. The main purpose of this survey is to study the cluster members and find the ionizing sources of the associated HII region.
