Hamid Hassani

#astronomy #extragalactic #galaxy #astrophysics

My goal with Neloura is to combine the strengths of widely used astronomical software into one flexible, Python-friendly package, while adding new analysis features tailored for JWST and multi-wavelength datasets. This is still the first version, but I’m excited to share it and continue improving!

6. On the server version (neloura.com), you can upload catalogs, download data, and run quick analyses. User uploads are temporary and automatically cleared after one hour.

4. Build spectral energy distributions (SEDs) from HST + JWST photometry in your catalog, with RGB cutouts (optimized for PHANGS but adaptable to any filter set).

5. Run artificial star injection tests to evaluate catalog completeness (as implemented in my paper)

2. Identify and analyze peaks using AstroDendro.

3. Create interactive scatter plots linked to to displayed map.

Neloura is a Python-based FITS file visualization, cataloging, and interaction tool that I developed to support this research. With Neloura, you can:

1. Open and explore your 2D FITS images, or download them directly from archives like MAST or NED.

Following the submission of my recent paper on cataloging compact sources in JWST observations of nearby galaxies, I’d also like to share the software behind this work, which I hope will be useful to the community.

Neloura:

GitHub repo: github.com/hamidnpc/Nel...

Online version: Neloura.com

Find Neloura at neloura.com. Here we reproduce Figure 26 of the paper for galaxy NGC 628, where you can load your catalog, view RGBs and SEDs, and see well-formatted properties, along with interactive features to locate any scatter point on the map viewer.

Find the code on GitHub: github.com/hamidnpc/Nel..., and the on-server version at neloura.com, which includes all PHANGS datasets (MUSE, HST, JWST, ALMA). Along with the 10 & 21 µm catalogs, you can interactively plot scatter plots and explore many other features!

Last but not least, (almost) all results in the paper are reproducible! I developed a Python-based FITS file visualization, cataloging, and interaction software called Neloura, which lets users generate SEDs, create RGB cutouts, perform peak finding, and run AST on JWST images!

We modeled 10 & 21 µm ISM luminosity functions with a Pareto-lognormal. The 21 µm slope (−1.7) matches GMCs & H II regions, while 10 µm is steeper (−2.0), like stellar clusters. The 21 µm slope tracks SFR, linking short-lived MIR emission (<5 Myr) to galaxy-wide star formation.

One of the interesting young clusters in our catalog shows bright F2100W emission (~1000 µJy), almost no Hα within the aperture, and a strong 3.3 µm PAH feature. MIRI PAH also traces a nearby GMC detected in CO(2–1) with ALMA. Photometry in all bands has been convolved to the F2100W filter.

Most 21 µm sources are young stellar clusters with Hα emission. “Embedded” clusters are <5% of the catalog (~10% of strong ISM), showing bright 10 & 21 µm emission and weak Hα (EW ~40 Å, ~3× lower). Both embedded & exposed phases share high 3.3um PAH/continuum ratios (~>1.5).

With detection limits in these bands, we classify stellar clusters as Hα-bright or Hα-faint. Using PARSEC models, we further classify sources into RSGs, O-AGBs, and C-AGBs, and with SAGE-LMC results from the literature into PNe, WRs, and B[e] stars

The study also provides a detailed completeness limits analysis for F1000W, F2100W, and HST Hα compact sources at 0.36″ and 0.67″ resolution. The procedure uses the common Artificial Star Test (AST), which involves injecting fake compact sources and attempting to recover them.

This first paper in the series catalogs sources in nearby galaxies, including Hα-bright clusters, optically embedded clusters, and stellar populations (RSGs, O-AGBs, C-AGBs, & more), classified with JWST NIRCam and MIRI from F200W to F2100W. This study expands on my 2023 work!

The Hidden Life of Stars: Embedded Beginnings to AGB Endings in the PHANGS-JWST Sample. I. Catalog of Mid-IR Sources We present a multiwavelength catalog of mid-infrared-selected compact sources in 19 nearby galaxies, combining JWST NIRCam/MIRI, HST UV-optical broadband, H$α$ narrow-band, and ALMA CO observations. W...

My recent PhD paper, titled “The Hidden Life of Stars: Embedded Beginnings to AGB Endings in the PHANGS-JWST Sample. I. Catalog of Mid-IR Sources”, is out!

The paper presents a catalog of JWST MIRI 10 µm and 21 µm sources across 19 nearby galaxies.
arxiv.org/abs/2509.16459